By Aparna Kher
One of Earth's greatest threats and mankind's biggest fears is the catastrophic impact of an asteroid and with good reason. Evidence remains of the devastation such impacts from the early history of Earth's formation caused. None so frightening as the impact that nearly wiped out all life a mere 66 million years ago. Asteroids are rocky worlds revolving around the sun that are too small to be called planets. They are also known as planetoids or minor planets. There are millions of asteroids, ranging in size.
Asteroids are small, atmosphere-less rocky objects orbiting the Sun. Here are 10 things that you might not know about these planet-like celestial bodies that can crash into the Earth and create havoc.
1. They were Created at the Same Time as the Earth
Many astronomers believe that asteroids are rocky leftovers from the formation of the Solar System 4.6 billion years ago. One theory is that after the Big Bang, dust particles came together to form celestial objects through a process called accretion – smaller objects came together with other small objects, creating larger space rocks. Some of these celestial rocks were able to grow large enough to develop their own gravity and became planets. Many others were held back from getting together by Jupiter's gravitation force. These became asteroids.
Because they revolve around the Sun like planets do, asteroids are also sometimes called planetoids or minor planets.
2. Most are Found in One Area
Of the millions of asteroids that inhabit our solar system, a majority can be found in a region between the orbits of Mars and Jupiter. This region is called the Asteroid Belt.
3. ..A Very Lonely Area
Imagining the Asteroid Belt as in the movies – a small strip of space littered with huge rocks intent on mowing down your space ship?
Well, imagine again because the Asteroid Belt is nothing like that. In fact it is a very lonely place for an asteroid. Astronomers estimate that the average distance between two asteroids in the asteroid belt is about 600,000 miles (966,000 km). This is about 2.5 times the distance between the Earth and the Moon. That is a lot of space between two neighboring asteroids!
4. Not all of Them Reside in the Belt
While most of the known asteroids live in the Asteroid Belt, there are many that orbit the Sun outside this belt. For example, Trojan Asteroids, named after the Trojan Wars in Greek Mythology, follow the orbits of a planet. Jupiter has two clusters of Trojans following its orbit around the Sun – the one ahead of the planet is called the Greek Camp and the one behind is known as the Trojan Camp.
In 2010, scientists discovered the first Trojan Asteroid, 2010 TK7, that follows the Earth's orbit.
Asteroids that are pushed close to the Earth's orbit are known as Near Earth Asteroids.
5. They Come in Different Sizes
Asteroids can measure anywhere between a few feet to several hundred miles in diameter. The largest asteroid known to man, Ceres, is about 590 miles (950 km) in diameter.
Astronomers estimate that if all the asteroids in the Solar System were put together, the size of the resulting rock will be much smaller than our Moon!
6. And Yet, some Asteroids have Moons
About 150 Asteroids are known today to have one or more moons orbiting them. The most famous of these is Dactyl, a small moon orbiting Ida, an Asteroid Belt asteroid.
7.They can be Classified According to their Composition
Most Asteroids fall into one of three groups based on their composition: C, S and M types. The composition is determined by how far the asteroid was from the Sun during the time of its formation.
About two-thirds of all asteroids are thought to be C type asteroids. These asteroids are very dark, with an average albedo of about 0.06 and are thought to have a similar composition as the Sun. They can be found in the outer regions of the Asteroid Belt
S type asteroids are considerably brighter with an average albedo of 0.16. These asteroids are usually found in the inner regions of the Asteroid Belt and are composed of iron and magnesuim silicates.
M type asteroids can be found in the middle of the Asteroid Belt and are much brighter than an average albedo of 0.19. These are mostly composed of Iron.
8. ..This makes Asteroids Attractive to Miners
Asteroid mining? That is no longer in the realm of science fiction. Asteroids are rich sources of metals like Iron, Platinum and Titanium, metals that humans use daily to build and create things. In addition, scientists believe that water present on the surface of these asteroids could be broken down and used as fuel for space vehicles.
While asteroid mining hasn't started yet, many companies around the world have started exploring the idea seriously.
9.Close Encounters of the Asteroid Kind
The Earth's atmosphere acts as a shield protecting us from meteoroids and other objects that populate space. When a meteoroid enters the atmosphere, it usually burns up before hitting the surface of the Earth. If any part of the meteoroid survives and hits the surface of the Earth, it is called a meteorite.
Sometimes however larger space objects collide with the Earth's atmopshere and impact the surface of the Earth. Scientists have identified about 100 sites on Earth that may have been impacted by a large asteroid or comet.
While no humans have been killed due to a meteorite in recent history, there is some worry among the scientific community about the possiblity of a large asteroid impact and the effect it may have on human life.
10. An Asteroid may have Killed the Dinosaurs
In fact, there is a theory prevalent among the scientific community that it was an asteroid that wiped out the dinosaurs. Many scientists believe that the epicenter of the mass extinction of the dinosaurs lies in the Chicxulub Crater, an impact crater that was discovered under the Yucatán Peninsula in Mexico.
If the dinosaurs had a space program, they would still be here.
As an example of the economic value of space resources, let's consider the smallest known M-type asteroid, the near-Earth asteroid known as 3554 Amun (two kilometers in diameter): The iron and nickel in Amun have a market value of about $8,000 billion, the cobalt content adds another $6,000 billion, and the platinum-group metals add another $6,000 billion.
— John S. Lewis, Mining the Sky.
There are two things you need to know about asteroids:
- Asteroids can make us extinct (the threat) — see Planetary Defense Page and Planetary Defense Library
- Asteroids can make us rich and provide homes for trillions of people (the promise).
The Promise
There are vast numbers of asteroids in near-Earth orbits, some of which are easier to access than the Moon. The potential mineral wealth of these asteroids is so great that huge profits could be made once we can start mining them for materials to be sold to markets on Earth. Like space solar power, this is one of the potential revenue sources for the large startup costs for the first space settlements.
Asteroids can also be an enormous boon to orbital settlements. Orbital settlements must import their materials from either the Moon or asteroids. Diverting a few small (30-70 meter diameter) asteroids into Earth orbit could supply all the materials needed for early orbital settlement development.
While early orbital settlements may well be in Earth orbit, eventually humanity will spread out across the solar system. Then asteroids become prime targets for new settlements. Hollowing out a large, solid asteroid and building homes inside has great appeal. Such a settlement will have ample materials in the form of the asteroid itself, and the large mass of the asteroid provides immediate and substantial radiation protection. With a little care radiation levels could be less than on Earth.
Settlement of a large asteroid could start with a relatively small tunnel, providing a home for workers that could be gradually extended over time to build large open spaces and wonderful living areas with a complex geometry, providing endless, safe exploration possibilities for the children.
Asteroids And Comets
Buy age of empires 2 for mac online download. While some asteroids are believed to be solid enough to be hollowed out for living space, others are known to be ‘rubble-piles,' barely held together by their weak gravity. While such asteroids cannot be hollowed out for living in, they are much easier to mine to provide materials for large numbers of orbital settlements.
The vast material resources of the asteroid belt beyond Mars may eventually provide home for the bulk of humanity.
See also:
- Asteroid Retrieval Feasibility Study, Keck Institute for Space Studies, Jet Propulsion Laboratory (2012) PDF 51 pages
- Asteroid Mining: Key to the Space Economy, by Mark Sonter
- Technologies for Asteroid Capture into Earth Orbit, by Stephen D. Covey
- The Technical and Economic Feasibility of Mining the Near-Earth Asteroids, by Mark Sonter (1998 paper)
- The Technical and Economic Feasibility of Mining the Near-Earth Asteroids, by Mark Sonter (1998 Master's Thesis updated 2012) PDF 207 pages
- Near-Earth Asteroid Mining, by Shane D. Ross (2001) PDF 24 pages
- The Role of Near-Earth Asteroids in Long-Term Platinum Supply, by Brad R. Blair (2000) PDF 15 pages
Links
Information about Asteroids
Asteroids Game Free Online
- Neofuel – Near Earth Orbit rocket fuel
- NASA photo gallery of asteroids.
- General information about asteroids.
