Lyceum B - Astronomy - Week 25 - The Asteroid Belt
- Apr 27, 2022
- 4 min read
Asteroids are thousands of chunks of rock and metal that orbit the Sun, mostly between the inner terrestrial planets and the outer, gas giants. They are smaller than any of the planets, some as small as a basketball.
Scientists still disagree on the origin of asteroids, but one theory is that they may be the remains of a planet that was smashed to bits in a space collision.
Asteroids are located mainly in a belt between Mars and Jupiter called the Asteroid Belt.
Some of the rocks located in the Asteroid Belt have been named, such as Gaspra, a 12 1/2 mile long asteroid.
Some day, we may mine the minerals that can be found in the asteroid belt.
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From solar system.nasa.gov
Some asteroids go in front of and behind Jupiter. They are called Trojans.
Asteroids that come close to Earth are called Near Earth Objects, NEOs for short. NASA keeps close watch on these asteroids.
Green are Jupiter trojans / white is the Asteroid belt / orange are Hilda asteroids (Hildas) and red are Near Earth Objects.
Facts About the Asteroid Belt
Asteroid Belt objects are made of rock and stone. Some are solid objects, while others are orbiting “rubble piles”.
The Asteroid Belt contains billions and billions of asteroids.
Some asteroids in the Belt are quite large, but most range in size down to pebbles.
The asteroid 1/Ceres is also designated as a dwarf planet, the largest one in the inner solar system.
We know of at least 7,000 asteroids.
The Asteroid Belt may contain many objects, but they are spread out over a huge area of space. This has allowed spacecraft to move through the region without hitting anything. The average distance between objects in the Asteroid Belt is quite large. If you could stand on an asteroid and look around, the next one would be too far away to see very well.
Asteroids get their names from suggestions by their discoverers and are also given a number.
The formation of Jupiter disrupted the formation of any worlds in the Asteroid Belt region by scattering asteroids away. This caused them to collide and break into smaller pieces.
Gravitational influences can move asteroids out of the Belt.
The Asteroid Belt is often referred to as the “Main Belt” to distinguish it from other groups of asteroids such as the Lagrangians and Centaurs.
The four largest asteroids in the belt are Ceres, Vesta, Pallas, and Hygiea.
There was a theory once that if you combined all the asteroids they would make up the missing “Fifth” rocky planet. Planetary scientists estimate that if you could put all that material that exists there today, it would make a tiny would smaller than Earth’s moon.
The abundances of precious metals, such as nickel, iron, and titanium (to name a few), and water make asteroids an attractive target for mining operations when humans decide to expand their presence through interplanetary space. For example, water from asteroids could serve colonies in space, while the minerals and metals would be used to build habitats and grow food for future space colony inhabitants.
Beginning 2013, companies interested in asteroid mining began announcing their plans for future operations on distant planetoids. In addition, NASA is looking into similar missions. The biggest obstacles to asteroid mining are the need to develop affordable spaceflight technology that would allow humans to get to the asteroids of interest.
Compare Asteroids Vesta, Ceres and Erods to Pluto and its Moon, Charon.
Asteroid Vesta:
Asteroid Ceres:
From space-facts.com:
Asteroids are mainly made of materials left over from the formation of the inner solar system worlds. Most of them orbit the Sun between Mars and Jupiter, although there are groups of them that orbit closer. Asteroids come in three composition classes. C-types (chondrites) are made of clay and silicate rocks. S-types are the so-called “stony” asteroids and are made mostly of silicate rocks and nickel-iron mixtures. M-types are metallic nickel-iron. These categories indicate how far from the Sun they formed in the early solar system.
While asteroid impacts were more common in the past, they aren’t as frequent today.
As asteroid impact some 65 million years ago contributed to the extinction of the dinosaurs. (It was one of several factors that affected all life on Earth at that time.)
Earth suffers an impact from an object the size of a football field about once every 2,000 years.
A car-size meteoroid ( a piece of asteroid) falls into Earth’s atmosphere about once a year. The result is a beautiful fireball, but the Metroid usually burns up before reaching the ground.
Asteroids are rich in precious metals and other metals, such as water.
Some asteroids are actually blown-out comets. The ices are gone, and all that’s left is the rocky material.
Some asteroids have moons of their own!
The best-known asteroids are 1 Ceres, which is 591 miles across, 2 Pallas (with a diameter of 338 miles) and 4 Vesta (roughly 360 miles across).
These are rocky minor planets, and astronomers observed them since the 1800s.
Ceres is a differentiated asteroid. That means it has a rocky core and an icy outer crust. It might have an internal ocean.
Pallas has a very irregular shape, and may be what’s left of an early protoplanet.
Vesta is very bright and is likely the leftover of a rocky protoplanet.
From space.com:
A day on Ceres lasts a little over 9 Earth-hours, while it takes 4.6 Earth-years to travel around the Sun.
The close proximity and low mass of Ceres have led some scientists to suggest that it could serve as a potential site for manned landings and a launching point for manned deep space missions.
Videos:
Professor Dave Explains
Venus: Earth's Sister Planet - 5:40 min
Mars: Crash Course Astronomy #15 - 10:11 min
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