Asteroid: Definition, Size, Difference, Visibility, Facts

Asteroids are small, rocky objects orbiting the Sun, primarily found in the asteroid belt between Mars and Jupiter. The asteroid belt contains over 1 million asteroids, with an estimated 1.1-1.9 million larger than 1 km (0.6 miles) in diameter. Asteroid sizes range from tiny 4-meter boulders to massive bodies like Ceres, measuring 946 kilometers (588 miles) in diameter. Most asteroids (90%) are less than 1 kilometer (0.6 miles) wide.

Asteroids differ from comets in composition and behavior. Asteroids are solid, rocky objects made of metals and rocky material, while comets consist of ice, dust, and rocky particles. Comets form bright tails when approaching the Sun due to ice vaporization, whereas asteroids remain unchanged.

Asteroid observation from Earth is possible through telescopes. Vesta, the brightest asteroid, is visible to the naked eye under exceptional conditions. Dark nights enable viewing of one or two asteroids with a 10 cm diameter telescope. Binoculars or small telescopes reveal Ceres, Pallas, and Hygiea.

Asteroids are relics from the solar system’s birth 4.6 billion years ago. Some asteroids became moons of planets through gravitational capture, like Mars’ moons Phobos and Deimos. Asteroids possess moons, rings, and tails of their own – the asteroid 243 Ida has a moon named Dactyl.

The first asteroid, Ceres, was discovered on January 1, 1801, by Italian astronomer Giuseppe Piazzi at Palermo Observatory. William Herschel coined the term “asteroid” in 1802. Scientists estimate approximately 1-2 billion asteroids exist in the solar system. The main asteroid belt between Mars and Jupiter contains 100 million to 1 billion asteroids.

Asteroids are classified into three main types: C-type (carbonaceous), S-type (silicaceous), and M-type (metallic). C-type asteroids account for 75% of all known asteroids and contain carbon-rich materials. S-type asteroids are composed of silicate minerals and are more reflective. M-type asteroids are primarily composed of iron and nickel.

Asteroids orbit the Sun in elliptical paths, completing one orbit in 3 to 6 years. Asteroids rotate on their axes as they revolve around the Sun, with rotation periods varying from hours to days. Asteroid surfaces are pitted and cratered, indicating geological inactivity. Asteroids lack significant atmospheres, although some possess thin exospheres.

Asteroids closest to Earth are listed in the table below. (Asteroid information is provided by NASA, and is updated daily.)

What is an asteroid?

An asteroid is a small, rocky object that orbits the Sun, primarily found in the asteroid belt between Mars and Jupiter. Asteroids range in size from tiny pebbles to massive bodies hundreds of kilometers across, with the largest, Ceres, measuring approximately 946 kilometers (588 miles) in diameter. Scientists classify asteroids into different types based on their composition, with the most common being rocky, metallic, or a combination of both. Asteroids are remnants from the early formation of our solar system, left over from the process that formed the planets billions of years ago. These airless bodies have no atmosphere and feature surfaces pockmarked with craters from impacts with other objects.

The asteroid belt between Mars and Jupiter contains the most asteroids . The asteroid belt spans 140 million kilometers (86 million miles) in width and extends 1.5 billion kilometers (0.9 billion miles) in length. Over 1.1-1.9 million asteroids larger than 1 kilometer (0.6 miles) exist in the asteroid belt. 

Asteroid composition includes silicate rocks, metals, and ice. Asteroid rock consists of olivine and pyroxene. Asteroid metal contains iron and nickel. Asteroid ice includes water and frozen volatiles like ammonia and methane. Asteroid surfaces feature regolith, craters, and diverse geological features.

Asteroid sizes range from a few meters to hundreds of miles wide. Ceres is the largest asteroid with a 946 kilometer (588 miles) diameter. The smallest asteroids measure only a few meters across. Asteroid surfaces contain evidence of surface water ice on some bodies.

Asteroids follow elliptical or circular orbits around the Sun. Asteroids orbit the Sun at varying speeds. The asteroid belt orbits 2.2 astronomical units from the Sun on average. Asteroid orbits are influenced by planetary gravity. 

How many asteroids are in the asteroid belt?

The asteroid belt contains over 1 million asteroids in total. Astronomers have cataloged approximately 7,000 known asteroids in the belt. Scientists estimate the asteroid belt holds between 1.1-1.9 million asteroids larger than 1 km (0.6 miles) in diameter. NASA reports the belt may contain 1-2 million asteroids larger than 0.8 kilometers (0.5 miles) in diameter.  Many more asteroids likely exist in the belt waiting to be discovered as researchers continue to study and explore this remnant of the early solar system.

How big are the asteroids in the asteroid belt?

Asteroids in the asteroid belt range from 10 meters (33 feet) to 946 kilometers (588 miles) in diameter.

Ceres, the largest object in the asteroid belt, is classified as a dwarf planet with an approximate size of 946 kilometers (588 miles) in diameter. Vesta, the largest asteroid, has a diameter of 530 kilometers (330 miles). Other large asteroids like Pallas and Hygiea measure up to 400 kilometers (250 miles) in length.

Over 200 known asteroids have a minimum diameter of 100 kilometers (62 miles). Astronomers estimate 1.1-1.9 million asteroids have a minimum diameter of 1 kilometer (0.6 miles). Asteroids with a minimum size of 1 kilometer (0.6 miles) are considered significant by researchers. Smaller asteroids range down to 10 meters (33 feet) in size.

What are the four largest asteroids in the asteroid belt?

The four largest asteroids in the asteroid belt are listed below.

• Ceres: Ceres is the largest asteroid with a diameter of 946 km (588 miles). The asteroid is classified as a dwarf planet, comprising about 30% of the asteroid belt’s total mass. Ceres has a mass of 9.44 x 10^23 kilograms, and is rounded by its own gravity
• Vesta: Vesta is the second-largest asteroid, measuring 530 km (330 miles) in diameter. Vesta is a rocky, differentiated asteroid with a surface of basaltic rock. The asteroid has a mass of 4.46 x 10^23 kilograms.
• Pallas: Pallas is the third-largest asteroid, with a diameter of 560 km (348 miles). Pallas is a stony-iron asteroid with a highly inclined orbit. The asteroid has a mass of 2.11 x 10^23 kilograms.
• Hygiea: Hygiea is the fourth-largest asteroid, measuring 450 km (280 miles) in diameter. Hygiea is a carbonaceous asteroid with a surface of water ice and darker organic material. The asteroid has a mass of 8.67 x 10^22 kilograms. 

The four largest asteroids in the asteroid belt are Ceres, Vesta, Pallas, and Hygiea. These massive bodies account for approximately half of the total mass of the entire asteroid belt.

Astronomers discovered these four asteroids in the early 19th century. Ceres was discovered in 1801, with Vesta, Pallas, and Hygiea following shortly after. T

What are the asteroids in the asteroid belt made of?

Asteroids in the asteroid belt are made of rock, metals, and carbon-rich materials. The composition varies among different types of asteroids. S-type asteroids contain silicate materials like olivine and pyroxene, along with some metals.

Metallic asteroids exist in the asteroid belt and are composed primarily of iron and nickel. These asteroids contain up to 90% iron and 10% nickel. Metallic asteroids are thought to be remnants of planetary cores that never formed into full planets.

Carbon-rich asteroids contain organic compounds and water. These asteroids are found more in the outer regions of the asteroid belt. Carbon-rich asteroids make up approximately 5% of all known asteroids.

Some asteroids in the outer belt contain ices, including water ice, ammonia, and methane. Icy asteroids are estimated to comprise about 5% of all asteroids. Silicate materials are present in many asteroids, in stony and carbonaceous types.

How big are asteroids?

Asteroids range from tiny 4-meter boulders to massive 530 kilometer (330  miles) bodies. Ceres, the largest asteroid, measures 946 kilometers (588 miles) in diameter. Vesta and Hygiea span 530 km (330 miles) and 450 km (280 miles) respectively. Toutatis reaches 5 kilometers (3 miles) across. Most asteroids (90%) are less than 1 kilometer wide (0.6 miles). The asteroid belt contains an average of 1-2 kilometer (0.6-1.2 miles) objects.

 Ceres, the largest known asteroid, boasts a diameter of 946 kilometers (588 miles) and an ellipsoidal shape with the longest axis of 964.4 kilometers (599 miles). Vesta, another giant among asteroids, measures 530 kilometers (330 miles) in diameter. Hygiea, a third notable large asteroid, has an approximate diameter of 450 kilometers (280 miles). The asteroid belt between Mars and Jupiter contains millions of these rocky bodies in various sizes. 

What is the biggest asteroid in our solar system?

Ceres is the largest asteroid in our solar system. Ceres occupies the position of largest body in the asteroid belt between Mars and Jupiter. The asteroid measures approximately 946 km (588 miles) in diameter. Scientists designate Ceres as a dwarf planet due to its size. 

Ceres accounts for a considerable portion of the total mass in the asteroid belt. The Dawn mission orbited Ceres from 2015 to 2016, revealing surface features such as craters and mountains. Evidence of water ice was discovered on Ceres’ surface during the mission. Ceres offers valuable insights into the early formation and evolution of our solar system.

How big is the biggest asteroid compared to Earth?

Ceres, the largest asteroid, measures 946 kilometers (588 miles) in diameter. Earth’s diameter is 12,742 kilometers (7,918 miles). Ceres is approximately 1/13th the size of Earth. Asteroids are significantly smaller than planets. Ceres has 1/4,000th the mass of Earth.

What’s the biggest asteroid that hit earth?

The Vredefort asteroid is the biggest asteroid that hit earth. This asteroid struck Earth 2.023 billion years ago. The Vredefort impact structure is Earth’s largest verified asteroid impact. The Vredefort crater measures approximately 300 kilometers (186 miles) in diameter. . 

When did a large asteroid crash into the Moon?

A large asteroid crashed into the Moon on September 11, 2013. Researchers published a study on this date about asteroid impacts affecting Earth’s climate. The impact was significant enough to potentially cause climate effects lasting thousands of years.

Astronomers observed another asteroid striking the Moon on February 23, 2023. The lunar asteroid impact released energy equivalent to 1-2 tons of TNT.

Large asteroid impacts pose ongoing risks to our planet and solar system. NASA’s OSIRIS-REx mission studied asteroid Bennu’s rotation and orbit changes to better understand asteroid behavior. The Yarkovsky effect causes unexpected asteroid behavior due to uneven solar heating.

Is an asteroid bigger than a comet?

Asteroids are larger than comets. Asteroids range from 1-1,000 km (0.6 – 621 miles) in diameter, while comets span 1-100 km (0.6 – 62 miles). Ceres, the largest asteroid, measures 946 km (588 miles) across. Halley’s Comet, a well-known comet, has a diameter of only 15 km (9.3 miles). Some overlap exists, with larger comets exceeding smaller asteroids in size.

Asteroid bodies are larger and more massive than comets. Asteroids range from 1-1,000 km (0.6 – 621 miles) in diameter. Asteroid mass ranges from 10^12 to 10^23 kilograms. 

Comets are smaller than asteroids. Comet size ranges from 10-40 kilometers (6-25 miles) across. Comet mass ranges from 10^9 to 10^15 kilograms. The average comet diameter is 1-10 kilometers (0.6-6.2 miles). Comet Hale-Bopp is the largest known comet with a diameter of 25-30 kilometers (16-19 miles).

Asteroid sizes overlap with comet sizes in the 1-10 kilometer range (0.6-6.2 miles). Many asteroids and comets fall within this common size category. Asteroid bodies larger than 10 kilometers (6.2 miles) in diameter are more numerous than comets of similar size.

The largest asteroids are significantly bigger than the largest comets. Ceres, the largest asteroid, has a diameter of 946 kilometers (588 miles). Hale-Bopp, the largest known comet, has a diameter of 25-30 kilometers (16-19 miles). Ceres is about 30 times larger in diameter than Hale-Bopp.

Are asteroids bigger than meteors?

Asteroids are significantly larger than meteors. Asteroids range from a few meters to hundreds of kilometers across. Ceres, the largest asteroid, measures 946 km (588 miles) in diameter. Meteoroids, small objects entering Earth’s atmosphere, range from sand-grain size to 1 meter. Meteors are visible light streaks produced by meteoroids burning up in the atmosphere.

Asteroids constitute large rocky bodies orbiting the Sun. Most asteroids reside in the asteroid belt between Mars and Jupiter. The asteroid belt contains over 1 million asteroids larger than 1 kilometer (0.6 miles) in diameter.

Meteors originate from much smaller objects called meteoroids. Meteoroids measure from dust-sized particles to about 1 meter across. Most common meteors are produced by meteoroids smaller than a grain of sand.

Meteoroids are fragments that have broken off from asteroids or comets. Meteors appear as streaks of light when meteoroids burn up while passing through Earth’s atmosphere. The visible light phenomenon of a meteor is caused by objects less than 1 millimeter in diameter.

Asteroids have significantly greater mass than meteors due to their larger size. Asteroid mass ranges from a few kilograms to billions of tons. Meteors have a mass less than 1 gram.

What is the difference between an asteroid and a comet?

Asteroids are solid, rocky objects made of metals and rocky material, found in the asteroid belt. Comets consist of ice, dust, and rocky particles from the outer solar system. Comets form bright tails when approaching the sun due to ice vaporization. Both formed in the early solar system billions of years ago.

Orbits and location distinguish asteroids from comets. Asteroids have circular orbits within the asteroid belt between Mars and Jupiter. Comets follow highly elliptical orbits, originating from the Oort Cloud or Kuiper Belt. 

Physical characteristics further differentiate asteroids and comets. Asteroids have irregular shapes, ranging from a few meters to hundreds of kilometers in diameter. Comets possess more spherical shapes due to their fragile composition. Asteroids sometimes have natural satellites or moons, while comets rarely exhibit satellites.

Appearance near the Sun varies between asteroids and comets. Asteroids remain unchanged when approaching the Sun, appearing as small, rocky objects. Comets develop a bright coma and tail near the Sun, stretching millions of kilometers long due to outgassing of volatile compounds.

Asteroid comets or active asteroids exhibit characteristics of both celestial bodies. These objects, like 133P/Elst-Pizarro, have asteroid-like orbits but display cometary activity near the Sun. Asteroid comets are found in the asteroid belt, showcasing a rocky composition with occasional coma or tail development.

Why do asteroids and comets differ in composition?

Asteroids and comets differ in composition due to their formation locations in the early solar system. The frost line in the solar nebula played a crucial role in determining their composition. Asteroids formed inside the frost line, approximately 2.7 astronomical units from the Sun. Temperatures inside the frost line were high enough for metals and rocky materials to condense.

Asteroids are composed primarily of metals like iron and nickel, as well as rocky materials such as silicates. Asteroids have densities ranging from 2-8 g/cm³, indicating their rocky or metallic composition. Comets formed outside the frost line in the outer solar system. Temperatures outside the frost line were too low for metals and rocky materials to condense, but allowed water, methane, and ammonia to freeze.

Comets are composed primarily of ice and dust. Comets have densities around 0.1-1.0 g/cm³, reflecting their porous and icy composition.

What do asteroids and comets have in common?

Asteroids and comets are remnants of early solar system formation. Asteroids and comets orbit the Sun. The solar system contains these celestial bodies. Asteroids primarily reside in the asteroid belt between Mars and Jupiter. Comets originate from the outer solar system. Formation process created these objects as leftover materials.

What is the difference between asteroids and meteors?

Asteroids are small, rocky objects orbiting the Sun in the asteroid belt. Meteoroids are small pieces of debris entering Earth’s atmosphere. Meteors occur when meteoroids burn up, creating bright streaks of light. Meteorites are meteors that survive atmospheric entry and land on Earth. Asteroids remain in space, while meteors interact with Earth’s atmosphere.

Composition distinguishes asteroids from meteors. Asteroids primarily consist of rock and metal. Meteors comprise small particles of rock, metal, or ice. Location separates asteroids from meteors. Asteroids reside in the asteroid belt between Mars and Jupiter. Meteors exist in Earth’s atmosphere.

Visibility contrasts asteroids and meteors. Asteroids remain invisible to the naked eye, except for the largest ones. Meteors appear as bright streaks of light in the night sky, called “shooting stars.” Origin differentiates asteroids from meteors. Asteroids formed from leftover material of the early solar system. Meteors originate from fragments of asteroids or comets.

Orbit distinguishes asteroids from meteors. Asteroids maintain stable orbits around the Sun. Meteors follow highly elliptical orbits approaching Earth’s atmosphere. Duration separates asteroids from meteors. Asteroids have orbited the Sun for billions of years. Meteors burn up in Earth’s atmosphere within seconds.

Impact on Earth differentiates asteroids from meteors. Asteroids potentially cause significant damage and mass extinctions upon impact. Meteors burn up in the atmosphere without posing significant threats. Frequency of occurrence contrasts asteroids and meteors. Asteroids are relatively rare with only a few thousand known in the asteroid belt. Meteors occur with thousands entering Earth’s atmosphere daily.

Scientific classification distinguishes asteroids from meteors. Asteroids classify as small bodies in the solar system. Meteors classify as meteoroids or meteorites depending on their location.

What is the difference between an asteroid and a meteorite?

Asteroids are small rocky objects orbiting the Sun, mostly found in the asteroid belt between Mars and Jupiter. Meteorites originate as meteoroids in space. Meteoroids enter Earth’s atmosphere, becoming meteors. Surviving meteors land on Earth’s surface as meteorites. Asteroids range from 1-1000 km (0.6-621 miles) in diameter. Meteorites are smaller, from sand-grain to boulder size.

Composition and origin distinguish asteroids from meteorites. Asteroids consist of rock and metal, forming 4.6 billion years ago in the early solar system. Meteorites contain stony, iron, or stony-iron compositions, resulting from fragmentation of asteroids or other celestial bodies.

Impact potential and frequency vary between asteroids and meteorites. Large asteroids rarely approach Earth but can cause significant damage or extinctions upon impact. Small meteorites enter Earth’s atmosphere, totaling tons daily, and burn up or cause minimal damage.

Visibility and scientific value differ for asteroids and meteorites. Asteroids appear as small moving points of light through telescopes, providing insights into early solar system dynamics. Meteorites create bright streaks when entering Earth’s atmosphere and offer direct evidence of space materials for examination on Earth.

Can you see asteroids from earth?

Telescopes allow observation of most asteroids from Earth. Vesta, the brightest asteroid, is visible to the naked eye under exceptional conditions. Dark nights enable viewing of one or two asteroids with a 10 cm diameter telescope. Binoculars or small telescopes reveal Ceres, Pallas, and Hygiea. Darkest skies and late evening provide optimal viewing conditions.

Naked eye observation is limited to the largest and closest asteroids under exceptionally dark skies. Vesta, one of the brightest asteroids, has a magnitude of around 6.5 and measures about 530 kilometers (330 miles) in diameter. Telescope observation is the most common method for viewing asteroids. Asteroids appear as small, faint dots that move slowly against background stars.

Night sky provides optimal viewing conditions for asteroids. Observers can best see asteroids when they are at opposition, opposite Earth from the Sun. Opposition makes asteroids appear brightest and highest in the sky. Clear, dark nights offer the best visibility for asteroid observation.

Identifying asteroids requires knowledge of their positions and movements. Star charts and planetarium software like Stellarium or SkySafari help locate asteroid positions. Observers should look for asteroids that are at least 10th magnitude in brightness. Notable asteroids for observation include Ceres (950 km/590 miles diameter), Vesta (530 km/330 miles diameter), Pallas (560 km/348 miles diameter), and Hygiea (410 km/255 miles diameter).

Asteroid observation demands patience, practice, and proper equipment. Observers can start with good binoculars or small telescopes and gradually upgrade their equipment. Planetarium software assists in finding the best viewing times and locations for specific asteroids. 

What does an asteroid look like from earth?

Asteroids appear as small, bright dots in Earth’s sky. Telescopes reveal irregularly shaped, rocky objects with varying sizes. Surfaces of asteroids are pitted, cratered, or lumpy. Shapes range from nearly round to potato-like. The brightness of asteroids changes due to rotation and sunlight angles. Asteroid sizes span from meters to kilometers in diameter.

 Asteroid pictures taken by spacecraft show unique features such as craters, valleys, and evidence of ancient rivers and lakes. Some asteroids have smooth surfaces, while others display heavily cratered and rugged terrains.

Does Jupiter save earth from asteroids?

Jupiter protects Earth from asteroids and comets. Jupiter’s massive size and strong gravitational pull, deflect, or capture potential threats. Jupiter’s location near the asteroid belt makes it an effective shield for inner planets. Jupiter’s gravity deflected a comet in May 1999 that could have collided with Earth. Jupiter’s protection is significant but not foolproof.

Jupiter acts as a “cosmic shield” by absorbing impacts from celestial bodies. In 1994, Jupiter collided with Comet Shoemaker-Levy 9, demonstrating its ability to intercept potentially dangerous objects. Jupiter disintegrated Asteroid 2009 DD45 in its atmosphere in 2009, further showcasing its protective capabilities. Jupiter’s gravity shapes the orbits of long-period comets and deflects or captures comets from the outer solar system.

Jupiter’s protective effects have limitations. Jupiter cannot influence all asteroids, especially those originating from different regions of the solar system. Jupiter’s gravity occasionally increases asteroid impact risk on Earth by altering their trajectories. Jupiter deflects only about 2.5% of inner solar system asteroids. Jupiter did not prevent the Chelyabinsk meteor impact in 2013, highlighting the limitations of its shielding effect.

Jupiter’s presence reduces overall asteroid threats to Earth but does not eliminate them entirely. Jupiter ejects an estimated 1,000 to 2,000 large asteroids from the solar system yearly. Jupiter’s gravity reduces comet impact probability on Earth by approximately 50%. Earth remains vulnerable to impacts from various celestial bodies despite Jupiter’s protective influence.

Can an asteroid offer a clue to life on Earth?

Asteroids offer crucial clues to life on Earth. Scientists analyze asteroid chemistry and processes to reveal secrets about life’s origins. Asteroids contain water and organic materials, essential building blocks of life. Research on asteroid composition provides insights into early solar system conditions. Asteroid studies contribute to understanding Earth’s formation and potential extraterrestrial life.

Asteroid life connections are supported by the presence of organic molecules on these celestial bodies. Asteroid origins date back 4.5 billion years, making them remnants of the early solar system. Asteroid history reveals a series of collisions and mergers, shaping their current composition. Asteroid bacteria have been discovered in some meteorites, resembling Earth bacteria in structure.

Asteroid organic molecules include amino acids and sugars, key building blocks for life. Asteroid clues to Earth’s past come from chemical analysis revealing water, ammonia, and methane. Asteroid chemical makeup ranges from stony to metallic to icy, with carbonaceous chondrites containing water and organic molecules. Asteroid molecules offer insights into the molecular building blocks present in the early solar system.

Asteroid ingredients delivered to Earth include water, organic compounds, and metals necessary for life. Asteroid impacts shaped Earth’s life history, with large impacts causing mass extinctions and smaller ones delivering life-giving ingredients. Asteroid pieces called meteorites provide pristine material for laboratory analysis. Asteroid samples returned by missions like Hayabusa2 allow detailed study of their composition and potential links to life’s origins.

What are fun facts about asteroids?

The fun facts about asteroids are listed below.

• Asteroids are relics from the solar system’s birth 4.6 billion years ago.
• Millions of asteroids orbit the Sun, with an estimated 1-2 million larger than 1 kilometer (0.6 miles).
• Some asteroids became moons of planets through gravitational capture, like Mars’ moons Phobos and Deimos.
• Asteroids possess moons, rings, and tails of their own – the asteroid 243 Ida has a moon named Dactyl.
• 10199 Chariklo features rings, and 3200 Phaethon displays a tail of dust and debris.
• Asteroids exhibit odd shapes ranging from spherical to elongated and irregular, like 21 Lutetia.
• Asteroids contain rich deposits of minerals and water ice, with 24 Themis having water ice mixed with organic material.
• Water gullies exist on some asteroids like 24 Themis, suggesting water flowed on their surfaces in the past.
• Asteroids create massive impacts on planets, such as the Chicxulub impact likely causing dinosaur extinction.
• Asteroids form the asteroid belt between Mars and Jupiter, representing remnant material that never coalesced into a planet.
• Asteroids range in size from small boulders to objects hundreds of kilometers wide, with compositions varying from rocky to metallic to icy.
• Most asteroids orbit between Mars and Jupiter in the main belt, stretching from 2.2 to 3.2 astronomical units from the Sun.

What is an asteroid made of?

Asteroids are primarily composed of silicate rocks and sometimes metals like iron and nickel. Rocky materials contain oxygen, silicon, and magnesium. Asteroids include carbonaceous substances rich in carbon molecules. Some asteroids contain water ice and other ices. Eros, a stony asteroid, has a composition similar to meteorites. Asteroid surfaces feature regolith – a mixture of dust, rocks, and rubble.

Asteroids contain various metals. Iron and nickel are the most abundant metals in asteroids, comprising up to 85% and 10% respectively in metallic asteroids. Precious metals like platinum and gold exist in small quantities, with some asteroids containing up to 0.1% platinum and 0.01% gold. Magnesium is present in about 1% of asteroid compositions, found in silicate minerals such as olivine and pyroxene.

Carbon-based materials are significant components of certain asteroids. Carbon-rich asteroids contain organic compounds, carbonates, and carbides. These asteroids formed in the outer solar system where low temperatures preserved volatile compounds.

Scientists classify asteroids based on their composition. Silicate-rich asteroids, known as S-type, make up about 90% of all asteroids. Metal-rich asteroids, classified as M-type, consist primarily of iron and nickel. Carbon-rich asteroids, designated as C-type, contain significant amounts of carbon-based materials and organic compounds.

How are asteroids formed?

Asteroids formed in the early solar system through accumulation of dust and particles. Small rocky bodies grew from dust clumps via gravitational forces. Planetesimals collided and merged, increasing in size. Jupiter’s gravity caused asteroid formation between Mars and Jupiter. Larger bodies fragmented upon collision, creating additional asteroids. Remnant planetesimals never grew large enough to form planets.

Planetesimals served as building blocks for planets and asteroids. Some planetesimals collided and merged to form larger bodies, while others fragmented due to collisions and gravitational forces. The resulting fragments became asteroids, small rocky bodies orbiting the Sun. Gravity played a crucial role in planetesimal fragmentation and collision, causing fragments to collapse and form new, smaller bodies.

The asteroid belt formed between Mars and Jupiter, stretching from 2.2 to 3.2 astronomical units from the Sun. Over 1 million asteroids larger than 1 kilometer (0.6 miles) exist in the asteroid belt, with most measuring just a few meters or less in diameter. 

Which planet’s formation was most responsible for the creation of asteroids in our solar system?

Jupiter’s formation was primarily responsible for asteroid creation in our solar system. Jupiter’s immense gravity disrupted the protoplanetary disk, preventing planet formation between Mars and Jupiter. Scattered material concentrated as small rocky bodies in the asteroid belt. Fragmentation of these bodies resulted in asteroid formation. Morbidelli et al. (2005) and Walsh et al. (2011) studied Jupiter’s role in shaping the asteroid belt.

Bodies collided due to Jupiter’s gravitational influence during this process. Collisions created fragments too small for Jupiter to accrete, ranging from dust-sized particles to objects hundreds of kilometers in diameter. Astronomers observe these fragments today as the asteroids populating the main asteroid belt.

Jupiter brought objects together through its gravitational pull, causing violent impacts. Fragments created by these collisions were unable to coalesce into a planet due to Jupiter’s disruptive influence. Jupiter was instrumental in preventing planet formation in the region now known as the asteroid belt, located between 2.2 and 3.2 astronomical units from the Sun.

Jupiter’s mass, 318 times that of Earth, continues to shape the asteroid belt through its gravity. Jupiter stabilizes certain asteroid populations, such as the Trojan asteroids at its Lagrange points. Jupiter’s formation and subsequent migration perturbed the protoplanetary disk, leading to increased collisional activity and further fragmentation of bodies in the asteroid region.

When were asteroids first discovered?

Asteroids were first discovered on January 1, 1801. Italian astronomer Giuseppe Piazzi identified Ceres, the first asteroid, at Palermo Observatory. Piazzi spotted Ceres while searching for a hypothetical planet between Mars and Jupiter. Ceres initially received planet classification but later became known as an asteroid. William Herschel coined the term “asteroid” in 1802.

The discovery of Ceres marked the beginning of asteroid research. Astronomers found other asteroids soon after Ceres. Heinrich Olbers discovered the second asteroid Pallas in 1802. Karl Ludwig Harding discovered the third asteroid Juno in 1804. 

These early discoveries led astronomers to realize a large population of small rocky objects orbited the Sun between Mars and Jupiter. Astronomers called this region the asteroid belt. The asteroid belt contains an estimated 1-2 million asteroids larger than 1 kilometer (0.6 miles) in diameter. Scientists believe the asteroid belt is a remnant of the early solar system. Asteroids in the belt are thought to be the remains of a planet that never formed.

Asteroid research has continued to advance over the years. Scientists now know asteroids are diverse objects with various shapes, sizes, and compositions. Astronomers have discovered over 800,000 asteroids so far. The study of asteroids continues to be an active research area.

Who discovered the first asteroid?

Giuseppe Piazzi, an Italian astronomer and priest, discovered the first asteroid on January 1, 1801. Piazzi spotted 1 Ceres at the Palermo Observatory. 1 Ceres, initially classified as a planet, is now considered a dwarf planet. The discovery revealed a new class of objects in the asteroid belt orbiting between Mars and Jupiter.

Piazzi’s discovery occurred during his search for a hypothetical “missing planet” between Mars and Jupiter. Johann Elert Bode’s Titius-Bode law had predicted the existence of this planet, prompting astronomers to investigate the region. Piazzi initially thought the object was a comet. Several nights of observation revealed the object was moving in a nearly circular orbit, leading Piazzi to realize its true nature.

Ceres orbits the Sun in the main asteroid belt between Mars and Jupiter. Ceres orbits at an average distance of 413 million kilometers (277 million miles) from the Sun, with an orbital period of approximately 4.6 Earth years.

Scientists initially classified Ceres as a planet. Subsequent discoveries of similar objects in the same region led researchers to recognize Ceres as part of a larger population of small, rocky bodies. Ceres was later reclassified as an asteroid and, in 2006, as a dwarf planet by the International Astronomical Union (IAU).

Piazzi’s discovery marked a major milestone in astronomy. The finding revealed a new class of celestial objects called asteroids and sparked interest in asteroid research among astronomers. Three more asteroids were discovered within the next few years: Pallas, Vesta, and Juno. These discoveries established the asteroid belt as a distinct region of our solar system.

What was the first asteroid discovered?

Ceres was the first asteroid discovered on January 1, 1801, by Giuseppe Piazzi in Palermo, Sicily. Initially considered a planet, Ceres was later classified as an asteroid and dwarf planet. Ceres is the largest object in the asteroid belt between Mars and Jupiter, measuring 946 km (588 miles) in diameter. The Dawn spacecraft orbited Ceres from 2015 to 2016.

Ceres’ discovery sparked great interest in studying the asteroid belt. Thousands of asteroids have been discovered since Ceres. Asteroid research has become a vibrant field of study. Scientists work to understand the formation and evolution of our solar system through asteroid research. Studying asteroids provides valuable insights into our cosmic neighborhood’s history and continues to be an active area of study today.

How many asteroids do scientists believe exist in the solar system?

Scientists estimate approximately 1-2 billion asteroids exist in the solar system. The main asteroid belt between Mars and Jupiter contains 100 million to 1 billion asteroids. Known asteroids number about 800,000. Millions remain undiscovered. The main belt houses an estimated 1.1 to 1.9 million asteroids larger than 1 kilometer (0.6 miles) in diameter.

How do scientists name asteroids?

Discoverers propose asteroid names to the International Astronomical Union (IAU) after multiple observations confirm orbits. IAU assigns permanent numbers and approves names meeting specific guidelines. Names reference mythology, scientists, or cultural icons. Asteroid 2309 Mr. Spock exemplifies naming after fictional characters. Asteroids receive designations based on orbits for scientific identification.

Asteroids receive permanent numbers once their orbits are well-determined. Asteroids become eligible for names after receiving permanent numbers. The International Astronomical Union (IAU) chooses asteroid names according to specific guidelines. Discoverers suggest names for asteroids they find, drawing inspiration from mythology, famous people, or places. Astronomers submit proposed asteroid names to the IAU for approval.

Tradition gives mythological names to many asteroids in the main asteroid belt. Asteroids that cross Earth’s orbit sometimes receive special names to highlight their potential significance. The asteroid naming process has been in place since the early 1800s, resulting in over 800,000 known asteroids in the solar system. Ceres and Vesta are examples of large named asteroids in the main belt, while Apollo is a well-known near-Earth asteroid.

What is unusual about asteroid Bennu compared to larger asteroids?

Asteroid Bennu exhibits an extremely rough rocky surface compared to larger asteroids. Bennu’s small 500-meter diameter provides enough gravity to retain boulders and rocks, making the surface uneven. The asteroid’s rapid 4.3-hour rotation and a unique composition of 72% water, 22% organic material contribute to Bennu’s unusual characteristics. Bennu poses a 1-in-2,700 Earth impact risk between 2175-2199.

Scientists classify Bennu as a “rubble pile” asteroid. It consists of loose rock and debris rather than a solid body, which is more typical for smaller asteroids. Bennu’s surface appears surprisingly rough and boulder-covered, unlike larger asteroids that have smoother surfaces. Bennu demonstrates activity and mass ejection, with particles and debris periodically expelling from its surface. Mass ejection behavior is very unusual for asteroids.

Bennu poses a relatively high potential as a hazardous Earth impactor in the late 22nd century. NASA calculates a 1 in 2,700 chance of Bennu impacting Earth between 2175 and 2199. Bennu completes one orbit around the Sun in 436.6 Earth days and comes close to Earth every six years. Scientists consider Bennu a prime target for study due to its proximity and unique characteristics.

Researchers believe Bennu is a primordial artifact from the early solar system. Its carbonaceous composition suggests it contains organic molecules and water, making it valuable for studying the origins of life. Bennu’s small size and rapid rotation cause it to behave like a liquid sphere. Surface material on Bennu shifts and flows over time through a process called “granular flow,” responsible for its unique shape and surface features.

What are the different types of asteroids?

The different types of asteroids are listed below.

• C-type asteroids: C-type asteroids are carbonaceous, containing carbon-rich materials, organic compounds, and water. These asteroids account for 75% of all known asteroids. C-type asteroids are dark in color with low albedo (0.03 to 0.07). These asteroids are primarily found in the outer asteroid belt. Examples of C-type asteroids are 1 Ceres and 10 Hygiea.
• S-type asteroids: S-type asteroids are silicaceous, composed of silicate minerals like olivine and pyroxene. These asteroids are more reflective with albedos ranging from 0.10 to 0.22. S-type asteroids are concentrated in the inner asteroid belt. These asteroids are thought to be remnants of planetary cores. Examples of S-type asteroids are 15 Eunomia and 3 Juno.
• M-type asteroids: M-type asteroids are metallic, primarily composed of iron and nickel. These asteroids make up 8% of all asteroids. M-type asteroids are dense with high albedo. These asteroids are found in the inner asteroid belt. Examples of M-type asteroids are 16 Psyche and 21 Lutetia.

Asteroids are classified into three main types: stony, metallic, and carbonaceous. Stony asteroids compose the majority, consisting of silicate rocks with moderate albedo. Metallic asteroids contain iron and nickel, reflecting 50-60% of sunlight. Carbonaceous asteroids have carbon-rich materials and low albedo. Additional classes include Trojan, Centaur, and Near-Earth asteroids. Spectral characteristics further differentiate asteroids, with some showing absorptions at 0.7 µm and 1.4 µm.

Where are most asteroids located?

Most asteroids are found in the main asteroid belt. The main asteroid belt orbits the Sun between Mars and Jupiter. Over 800,000 known asteroids reside in this region, located 2.2-3.2 astronomical units from the Sun. The belt contains rocky, metallic, and icy bodies, including notable asteroids like Vesta, Ceres, Pallas, and Hygiea.

The main asteroid belt contains the highest concentration of asteroids in the solar system. The Asteroid belt consists of leftover primordial material from solar system formation. The asteroid belt contains between 1 and 2 million asteroids larger than 1 kilometer (0.6 miles) in diameter. Smaller asteroids exist in even greater numbers in the belt. 

What does an asteroid look like?

Asteroids look diverse in appearance. Shapes range from nearly spherical to irregularly lumpy. Sizes vary from pebble-sized (1 meter) to mountain-sized (over 1,000 kilometers). Surfaces appear pitted, cratered, and covered in loose rock (regolith). Compositions include metal, rock, and ice.

Asteroid surfaces are pitted and cratered from impacts with other bodies. Craters range from 1 to 20 kilometers (0.6-12.4 miles) in diameter on asteroids like 253 Mathilde. Asteroid surfaces are rugged and resemble rocky, mountainous terrain. The asteroid 21 Lutetia has a highly irregular shape measuring 96 kilometers (60 miles) long and 72 kilometers (45 miles) wide.

Asteroids rotate on their axes as they orbit the Sun. Rotation periods range from 2 to 100 hours for different asteroids. Some asteroids tumble chaotically, creating complex changing appearances. The asteroid 16 Psyche rotates every 4 hours and 12 minutes.

Asteroids resemble rugged, jagged chunks of rock or pieces of mountains up close. The asteroid belt contains millions of these rocky objects between Mars and Jupiter. Spacecraft images reveal asteroid composition and surface features in detail. The NEAR Shoemaker spacecraft imaged asteroid 253 Mathilde in 1997, showing its dark, carbonaceous surface with craters and grooves.

How can asteroids be distinguished from stars in telescope observations?

Asteroids move relative to the fixed celestial background of stars. Astronomers observe this motion over time to distinguish asteroids from stars in telescope observations. Position comparisons against fixed stars reveal asteroid movement. Object tracking across multiple observations confirms asteroid identification.

Changes in the celestial background indicate asteroid presence. Stars remain fixed while asteroids exhibit relative movement. Motion detection is the primary method for identifying asteroids. Astronomers compare object positions over time to detect asteroid motion.

Asteroid belts contain high concentrations of these moving objects.  Asteroids appear as small, faint points of light in telescope observations. Asteroid trails are light streaks caused by their motion during observation periods.

Astronomers conduct asteroid searches using various techniques. Sky surveys, trail observations, and known asteroid tracking are common search methods. Specialized software analyzes telescope images to detect faint asteroid trails.

Asteroids exhibit characteristic traits in telescope observations. Asteroid brightness varies more than star brightness. Asteroids tend to have more elongated shapes than point-source stars. These additional characteristics help astronomers distinguish asteroids from stars.

What color are asteroids?

Asteroids exhibit a gray color ranging from light to dark reddish hues. Silicate rock contributes to their common gray appearance. Some asteroids display greenish tints. Others show brown or clay-like colors. Stony asteroids have lighter hues. Carbonaceous asteroids appear darker and reddish. Metallic asteroids present mixed colors due to complex compositions. Asteroid color indicates composition and origin.

The majority of asteroids in the asteroid belt exhibit reddish hues. D-type asteroids display a burgundy color due to their organic-rich composition. Blue asteroids exist as rare exceptions in the asteroid population. Phaethon stands out as the bluest known asteroid in the asteroid belt. Some asteroids appear yellow, though this color is relatively uncommon.

Asteroids do not form a uniform population in terms of color distribution. The Sloan Digital Sky Survey (SDSS) conducted an asteroid survey revealing diverse colors among asteroids. The asteroid belt contains asteroids with a wide range of spectral features. Researchers use asteroid colors to gain insights into their composition and origin.

Do asteroids have tails?

Asteroids do not form tails like comets. Comets show tails of ice and dust when approaching the sun. Sun’s heat vaporizes comets’ ice, creating a dust trail. Active asteroids, a rare subset, sprout tails near the sun. Sun’s heat blasts surface material from active asteroids, leaving a dust trail behind.

Asteroids and comets have distinct characteristics. Asteroids consist primarily of rock and metal. Comets contain significant amounts of ice and dust. Asteroids maintain a stable appearance as they orbit. Comets undergo dramatic changes, forming tails millions of kilometers long.

Active asteroids represent rare exceptions to the no-tail rule. Active asteroids exhibit comet-like behavior under certain conditions. Collisions or other events can create temporary dust trails on asteroids. The asteroid P/2010 A2 (LINEAR) displayed a tail-like feature in 2010. Asteroid (3200) Phaethon has a debris trail from particle ejection.

Asteroids appear as point-like objects in the night sky. Asteroids lack visible tails or comas when observed from Earth. Comets show bright tails visible to the naked eye. 

What are the characteristics of asteroids?

The characteristics of asteroids are listed below.

• Asteroids orbit the Sun in elliptical paths.
• Most asteroids complete one orbit in 3 to 6 years.
• Asteroids rotate on their axes as they revolve around the Sun.
• Some asteroids rotate rapidly, like 16 Psyche which completes a rotation in 4.2 hours.
• Other asteroids rotate more slowly, such as 1 Ceres which takes 9.1 hours to complete one rotation.
• Asteroids are irregularly shaped objects lacking fixed symmetry.
• Asteroids can be spherical, elongated, or dumbbell-shaped.
• Asteroids have pitted and cratered surfaces, indicating geological inactivity.
• 1 Ceres exhibits a heavily cratered surface, while 16 Psyche has a smoother appearance.
• Asteroids are small rocky and metallic objects.
• They range in size from a few meters to nearly 1000 km (621 miles) in diameter.
• Asteroids lack significant atmospheres.
• Some asteroids possess thin exospheres.
• Asteroids are primarily composed of rock and metal.
• Asteroids are classified into three main types: C-type (clay and silicate rocks), S-type (silicate materials and nickel-iron), and M-type (mainly nickel and iron).
• Some asteroids contain water ice.

Asteroids are irregularly shaped objects lacking fixed symmetry. They can be spherical, elongated, or dumbbell-shaped. 

How fast do asteroids travel?

Asteroids in the asteroid belt travel at speeds ranging from 17 to 25 kilometers (11-16 miles) per second. Asteroid speeds depend on their specific orbit and distance from the Sun. Inner asteroid belt objects move faster than outer belt objects. The average speed of an asteroid is approximately 20 km/s (12.4 miles/s). The Sun’s gravitational pull influences asteroid velocities.

Asteroid speeds increase dramatically when approaching Earth. Asteroids strike Earth at 16-32 kilometers per second (10-20 miles per second). The fastest recorded asteroid impact on Earth reached 102,998 kilometers per hour (64,000 mph). Small asteroids at lunar distance travel at 21 km/s or 47,000 mph.

Asteroid speed is determined by orbital path and gravitational forces. Asteroids further from the Sun move more slowly. Asteroids closer to the Sun move faster due to stronger gravitational pull. Asteroid watch programs monitor asteroid speeds and trajectories to predict potential impacts and provide early warnings for planetary defense.

Can asteroids have moons?

Asteroids have moons. Astronomers discovered multiple asteroid-moon systems. Binary systems consist of two similarly-sized asteroids orbiting each other. Triple systems include two small moons orbiting a large asteroid. 243 Ida’s tiny rocky moon Dactyl orbits 90 kilometers (56 miles) away. 90 Antiope forms a double asteroid system with its large companion. Only 1% of asteroids possess moons.

Asteroid moons are natural satellites that orbit around larger asteroids. Notable examples include Dactyl orbiting 243 Ida, Petit-Prince orbiting 45 Eugenia, and S/2001 (22) 1 orbiting 22 Kalliope. Researchers detect and study asteroid moons using advanced telescopes and spacecraft observations. The Gaia space telescope observed potential moons around 350 more asteroids, suggesting asteroid moons are more common than previously thought.

Asteroids exert gravitational influence on nearby objects. An asteroid’s ability to capture and retain moons depends on its mass and radius. Larger asteroids have stronger gravity, making them more likely to hold moons. 243 Ida, with a diameter of 53 kilometers (33 miles) and a mass of 4.2 x 10^16 kilograms, successfully holds its moon Dactyl in orbit.

Asteroid moons vary in size and shape. S/2004 (87) 1, orbiting asteroid 87 Sylvia, is the largest known asteroid moon at 10 kilometers (6.2 miles) in diameter. S/2005 (45) 1, orbiting asteroid 45 Eugenia, is among the smallest at 6 kilometers (3.7 miles) in diameter. Asteroid moons orbit their parent bodies at distances ranging from tens to hundreds of kilometers. Dactyl orbits Ida at a distance of 90 kilometers (56 miles) with an orbital period of 37 hours.

Asteroid-moon systems form through various processes. Collisions between asteroids blast off material that can coalesce into moons. Some asteroids and their moons co-form from early solar system material. Larger asteroids capture smaller objects through their gravitational pull. These diverse formation mechanisms contribute to the wide variety of asteroid-moon systems observed in the asteroid belt between Mars and Jupiter.

Do asteroids orbit the Sun?

Asteroids orbit the Sun. Asteroid orbits are highly elliptical, unlike planets. Orbits span from close to the Sun to outer reaches of the solar system. 

Asteroid velocities range from 15-25 km/s (9.3-16 miles/s). Asteroid 16 Psyche has a velocity of 20 km/s (12.4 miles/s). Orbital periods vary depending on distance from the Sun and orbit shape. Asteroid 1 Ceres has an orbital period of 4.6 Earth years.

Asteroid orbits differ from planetary orbits in shape and size. Many asteroids have inclined orbits above or below the solar system plane. Some asteroids have retrograde orbits opposite to the planets. Jupiter’s gravity significantly influences asteroid orbits, changing their paths or ejecting them from the solar system.

Astronomers study asteroid orbits using various detection methods. NASA’s Dawn spacecraft orbited asteroid Vesta in 2011-2012. Orbital analysis provides insights into solar system formation and evolution. 

Why are asteroids mostly irregular in shape?

Asteroids possess irregular shapes due to insufficient mass gravity. Scientists like Gyula Springmann confirm asteroids’ probable irregularity. Asteroids form from collided and merged debris piles. Low mass prevents asteroids from achieving spherical shapes. Mass gravity determines celestial object forms. Larger objects like planets have enough mass to become spheres, while smaller asteroids remain irregular.

Formation processes contribute significantly to asteroids’ irregular shapes. Many asteroids formed through collisions and merging of smaller bodies in the early solar system. Asteroid 16 Psyche exemplifies this irregularity, with its long axis 1.5 times longer than its short axis. Asteroids do not rotate fast enough to generate significant centrifugal force, which could potentially create more symmetrical shapes.

Larger celestial bodies contrast sharply with asteroids in terms of shape. Planets and large moons possess stronger gravity, allowing them to deform rocks and pull materials into spherical shapes. Earth’s gravity, at 9.8 meters per second squared, is strong enough to achieve hydrostatic equilibrium and form a nearly perfect sphere. Asteroids in the asteroid belt, located between Mars and Jupiter, display a wide range of irregular shapes due to their low mass and insufficient gravity.

How much do asteroids weigh on average?

Asteroids vary greatly in weight, ranging from a few grams to billions of tons. The total mass of the asteroid belt is estimated at 3 x 10^21 kg. Ceres, the largest asteroid, has a mass of 9.3 x 10^20 kg and measures approximately 946 kilometers (588 miles) in diameter. Near-Earth asteroids have a combined mass of around 60 million metric tons. A large asteroid capable of causing catastrophic damage if it were to strike Earth. Carbonaceous asteroids, composed of organic materials, can weigh significantly less. A 66-foot wide carbonaceous asteroid has an estimated mass of 6,459 tons. Meteorites, which are fragments of asteroids that land on Earth, can have masses as small as 10 grams. The vast range in asteroid masses reflects the diversity of these celestial bodies and their importance in understanding the early solar system.

Do asteroids have gravity?

Asteroids possess gravity due to their mass. Gravitational force strength depends on asteroid size and density. Larger, more massive asteroids exert stronger gravitational pull on nearby objects. Asteroid gravity is weaker than planetary gravity. 

Larger asteroids possess stronger gravitational forces. Ceres, the largest asteroid with a diameter of 946 kilometers, has a surface gravity of 0.27 m/s², compared to Earth’s 9.8 m/s² . Smaller asteroids have much weaker gravity. A 1-kilometer (0.6 miles) asteroid has a surface gravity of only 0.0006 meters per second squared.

Asteroid mass directly correlates with gravitational strength. Ceres has a mass of 9.4 x 10^23 kilograms, resulting in its relatively stronger gravity. A typical 1-kilometer (0.6 miles) asteroid has a mass of 1.4 x 10^12 kilograms, leading to its minimal gravitational pull.

Asteroid gravity affects nearby objects in space. Large asteroids can perturb the orbits of passing objects or other asteroids. Most asteroids in the asteroid belt between Mars and Jupiter are loose rubble piles held together by their own weak gravity.

Can an asteroid be pure metal?

Yes, asteroids can be pure metal. Metallic asteroids consist entirely of metallic materials, primarily iron and nickel. Asteroid 16 Psyche is believed to be a purely metallic body, likely the remains of a destroyed planetary core. Metallic asteroids formed in the early solar system when the solar nebula was rich in metals.

Asteroid composition varies widely across the asteroid belt. Asteroid 16 Psyche, believed to be a remnant planetary core, has an estimated density of 4.2 g/cm³. Asteroid cores can be metallic in differentiated asteroids, but surfaces experience space weathering and impacts. Asteroid surfaces develop regoliths with mixed compositions over time. M-type asteroids contain primarily iron and nickel, representing the most metal-rich objects in the asteroid belt. Asteroid Vesta, with a diameter of approximately 530 km (330 miles), has a basaltic rock surface with some metal deposits.