Special Sub-Topic: Twenty Questions About Asteroids Click Here To Play: Twenty Questions About Asteroids

The first asteroid, 1 Ceres, was discovered on Jan 1, 1801, who discovered it?

Giuseppe Piazzi. 1 Ceres was not only the first asteroid discovered, it is also the largest known asteroid being some 933 kilometers long. The planet Uranus was only discovered 20 years earlier. Giuseppe Piazzi was born at in Valtellina, on July 16, 1746. He died at Naples, on July 22, 1826.

Asteroids are sometimes called _____________.

Planetoids. This name is rarely used anymore, but is still accurate.

The main asteroid belt is situated between _______________.

Mars and Jupiter. The main asteroid belt is about 2 - 4 AU from the Sun. AU stands for astronomical unit. One astronomical unit equals about 93 million miles, the distance between the Sun and Earth. The reason I call it the main asteroid belt is because beyond Neptune is another asteroid belt that is called the Kuiper belt. The Kuiper belt includes the planet Pluto, the ninth planet in our Solar System. Pluto is by far the largest Kuiper belt object found to date.

What was the name of the second asteroid discovered?

Pallas. For obvious reasons, I deliberately omitted the number preceding the name. 2 Pallas was discovered in 1802 by a German astronomer and physician Wilhelm Olbers. 3 Juno, 4 Vesta and 433 Eros are three other asteroids.

With the exception of Comets (being named after the person that finds them)minor planets are the only astronomical objects that may be named after living people.

t. It is true that an astronomer named a pair of stars after himself by spelling his name backwards. Those stars are Sualocin (Alpha Delphini), which is Nicolaus spelled backwards and Rotanev (Beta Delphini) is Venator spelled backwards. This is no longer allowed. The discoverer of the minor planet or asteroid can name the asteroid anything they wish (except after themselves).

Asteroids that come within the orbit of the Earth at their perihelions (closest approach to the Sun) are known as ___________ asteroids.

Apollo. The first Apollo asteroid was discovered in 1918 by Max Wolf observing from Heidelberg, Germany. There are about 240 known Apollo asteroids.

Asteroids that are always closer to the Sun than the Earth are called __________ asteroids.

Aten. The first Aten asteroid was discovered in 1976 by JPL astronomer Eleanor Helim. There are at least 30 known Aten asteroids. The reason there are so few Aten asteroids is that it is difficult to hunt for them since they are between Earth and the Sun.

What asteroid is dog-bone shaped?

216 Kleopatra. This was probably a tough one to know. 216 Kleopatra measures about 135 miles long and about 58 miles wide. Kleopatra was discovered in 1880.

If all of the asteroids were lumped together, they would make a planet bigger than Jupiter.

f. Even though there are about 100,000 known asteroids, they are mostly small. If they were all lumped together, they would make an object smaller than Earth's Moon.

Which minor planet (asteroid) reaches the greatest brilliance (as seen for the Earth)?

4 Vesta. 4 Vesta gets as bright as 6th magnitude, so it can be seen with the naked eye in a very dark sky. It is easy in a telescope when this bright. Several meteorites are believed to be from 4 Vesta due to the similarity of their spectra with the spectrum of 4 Vesta.

What asteroid did the NEAR Shoemaker mission recently land on?

433 Eros. On February 14, 2000, the NEAR Shoemaker spacecraft achieved orbit around 433 Eros. It landed a year later at the end of its mission. Eros is one of the larger Amor asteroids, Amor asteroids are Mars crossing asteroids. There are 231 known Amor asteroids as of 2002.

Most meteorites probably originate from the asteroid belt.

t. Some may possibly come from comets and others definitely come from the Moon and Mars.

The Galileo spacecraft had encounters with two asteroids while enroute to Jupiter, what are the names of the asteroids?

243 Ida and 951 Gaspra. 243 Ida and 951 Gaspra are main belt asteroids, they were imaged by Galileo and 243 Ida was found to have a satellite asteroid going around it, named Dactyl. The Galileo spacecraft had no problems going through the asteroid belt. For that matter neither did the two Pioneer spacecraft, the two Voyager spacecraft or the Cassini spacecraft. Why? Because, unlike Science Fiction movies, the main asteroid belt is very sparse. The distance between most asteroids is about one million miles.

Which asteroid was discovered to have its own satellite?

243 Ida. 243 Ida satellite is Dactyl, and the permanent name is (243) Ida I. Dactyl is 1.6 x 1.2 km in size. Ida was encountered Aug. 28, 1993, by the Galileo spacecraft, which was enroute to Jupiter.

How many asteroids have diameters greater than 240 kilometers?

16. Including three of the first four discovered; 1 Ceres is 933 km, 2 Pallas is 522 km and 4 Vesta is 530 km.

Between the main concentrations of asteroids in the main belt are relatively empty regions known as the _______________.

Kirkwood gaps. The large gaps within the asteroid belt may be the result of asteroid collisions. Another explanation is that the gaps were formed as a result of gravitational interactions with Jupiter. Cassini's division is between Saturn's A and B rings, the Van Allen belts are around Earth and the Kuiper belt is an asteroid belt outside the orbit of Neptune.

What asteroid is believed to be associated with a meteor shower?

3200 Phaethon. This asteroid was discovered on 8/31/1983. It is believed to be the source of the Geminid meteor shower (which peaks in mid December). The first Geminid meteors suddenly appeared in 1862. In 1983, NASA's Infrared Astronomical Satellite discovered 3200 Phaethon traveling in the same orbit as the Geminid meteoroid stream. It is the only known asteroid associated with a meteor shower.

The majority of asteroids fall into which three categories?

C-type; S-type and M-type. The C-type asteroids, includes about 75% of all known asteroids. C-type asteroids are the darkest, similar to carbonaceous chondrite meteorites. Like Allende and Murchison. S-type asteroids are about 17% of the total. These are rather bright metallic nickel-iron asteroids with silicates. These are probably similar to the H (High Iron) and L (Low Iron) chondrites (meteorites). The next major tpe are the M-type. These are somewhat bright, and are pure nickel-iron, similar to the nickel-iron meteorites, like Canyon Diablo and Sikhote-Alin. There are many minor categories as well.

What are NEO's?

Near Earth Objects. Near-Earth Objects (NEOs) are comets and asteroids that have had their orbits changed by the gravitational attraction of nearby planets (or other asteroids) into orbits that allow them to enter the Earth's neighborhood. Some of them are also called NEA (Near Earth Asteroids).

How do scientists know that some meteorites are from Mars?

Atmosphere of Mars matches atmosphere in some meteorites. Although most asteroids are the parent source of meteorites, there are exceptions. Meteorites (especially from Antartica) are carefully preserved and transported to research centers (like the one in Houston). Here the meteorites are examined and some of them contain vugs (cavities) and in some of these vugs is air. This air can be extracted and its composition identified. The air matches up rather closely with the results of the Viking missions (that landed on Mars) back in 1976. Only about 24 meteorites have been classified as Martain. Most of these meteorites are from Antartica, however, a few of them have been found elsewhere on the Earth.