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Sunday, 18 September 2011

Asteroid

About 100,000 asteroids may exist, but their total mass is only a few hundredths of the mass of the Moon. These rocky fragments range in size from 1 km/0.6 mi to 900 km/560 mi in diameter.


The first person to discover an asteroid was Italian priest and astronomer Giuseppe Piazzi in 1801. He discovered Ceres on January 1, 1807 naming it after the Roman goddess of agriculture. Ceres is 582 miles in diameter, the largest object in the asteroid belt that lies between the orbits of Mars and Jupiter. It is the only dwarf planet within the orbit of Neptune.

The word ‘asteroid’, meaning star-shaped, was coined by William Herschel in 1802.

German astronomer Heinrich Wilhelm Matthäus Olbers discovered 4 Vesta, the brightest asteroid and the second-most massive body in the asteroid belt in 1807.

Discovered on December 22, 1891, 323 Brucia was the first asteroid to be found by the use of astrophotography. It was also the first of over 200 asteroids discovered by Max Wolf, a pioneer in that method of finding astronomical objects.


In March 1989 an asteroid passed through the exact position where Earth was only six hours earlier.

On October 29, 1991 Galileo became the first spacecraft to visit an asteroid when it made a flyby of 951 Gaspra.

NASA image of 951 Gaspra; colors are exaggerated

NASA's robotic space probe NEAR Shoemaker touched down on Eros on February 12, 2001, becoming the first spacecraft to orbit and soft land on an asteroid. To the surprise of the controllers, the spacecraft was undamaged and operational after the landing at an estimated speed of 1.5 to 1.8 meters per second.



Between 2006 and 2007, an asteroid about five meters across was temporarily captured by Earth’s gravity, giving us a tiny second moon for about nine months.

The Japanese Hayabusa space mission was the first to return samples of an asteroid (25143 Itokawa) to Earth for analysis.

After arriving at Itokawa, in November 2005, Hayabusa landed on the asteroid and collected samples in the form of tiny grains of asteroidal material, which were returned to Earth aboard the spacecraft on 13 June 2010.

The Jupiter trojans are a large group of asteroids that share the orbit of the planet Jupiter around the Sun. The first one discovered, 588 Achilles, was spotted in 1906 by German astronomer Max Wolf. By convention they are named after mythological figures from the Trojan War. Around one million of them are larger than 1 km in diameter.

TK7 was the first Trojan asteroid discovered sharing the Earth's orbit around the Sun. It was discovered in October 2010 by astronomers from Athabasca University, UCLA, and University of Western Ontario.

On January 22, 2014, ESA scientists reported the detection, for the first definitive time, of water vapor on Ceres. The finding was unexpected because while comets are typically considered to sprout jets and plumes, asteroids do not generally exhibit such features.

Ceres Wikipedia commons

An asteroid hits the ground about 1,000,000,000,000,000,000 times harder than a raindrop.

Any asteroid 82 feet (25 m) in diameter or less won't make it to Earth's surface—it will burn up in the planet's atmosphere.

A space vehicle can travel safely through the asteroid belt. The distance between two objects in the asteroid belt ranges in the hundreds of thousands of miles. Chances of hitting one of them are 1 in 1,000,000,000.

Ceres is the largest asteroid. It is 940 km/584 miles in diameter.

Vesta has a light-colored surface and is the brightest asteroid as seen from Earth.

A 100 mile-long asteroid in our solar system, 241 Germania, is believed to boast mineral wealth worth $95.8 trillion — nearly equivalent to the world’s total annual gross domestic product.

NASA believes the value of minerals on the asteroid belt exceeds $600,000,000,000,000,000,000.

The Kuiper belt is a circumstellar disc in the Solar System extending beyond the orbit of Neptune, at 30 to 50 astronomical units from the Sun. It is similar to the asteroid belt between Mars and Jupiter, but far larger—20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies that are remnants from the Solar System's formation.

The Kuiper belt is home to three officially recognized dwarf planets: Haumea, Makemake, and Pluto, the largest and most massive member.

Sources Daily Express, Hutchinson Encyclopedia © RM 2011

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