Asteroids and Life

Jupiter-Size Planet Orbiting Outside Asteroid Belt

   Based on recent observations a team of Astronomers are suggesting that the presence of an asteroid belt with a Jupiter-sized planet in orbit just outside the asteroid belt could be an advantageous situation to life developing on planets between the asteroid belt and the star these objects orbit. The thinking is that asteroids are held in place by the gravitational influence of the Jupiter-size planet and were prevented from coming together forming larger bodies by repeated collisions that ultimately reduces the sizes as well as ejecting some of the objects inward toward the Sun and collisions with inner planets. These objects could have been responsible for bringing some water and other ices to the inner planets, as well as having an impact (literally) on any life forms.
   With our solar system as a model the team of Astronomers observed stars and found evidence that was consistent with their model and ideas – suggesting perhaps another method for searching for exo-solar systems, especially those similar to ours with an asteroid belt and Jupiter-size planet.
   Click here to read the press release.
   The Asteroid Belt:

The Main Asteroid Belt

   This area of the solar system, between the orbits of Mars and Jupiter, consists of rocky and possibly icy objects of varying sizes and shapes. The largest member is the 957 km (595 miles), spherically shaped 1 Ceres, now designated as a dwarf planet. This was also the first asteroid discovered, and initially considered to be a planet, as were the next three asteroids to be discovered: Pallas (524 km, 326 miles) , Juno (274 km, 170 miles), and Vesta (512 km, 318 miles). Of all the asteroids currently discovered and cataloged (150,000), only Ceres had enough mass during its formation to have the gravitational strength to become spherical. Typically, all other smaller asteroids are elongated or oblong in their shape, and some even appear to be composed of smaller pieces held closely together by their mutual gravitational fields.
   Asteroids, like the planets, orbit the Sun in the same direction. However, they are in orbits that are more elliptically shaped and more steeply inclined, averaging 20–30°above or below the plane of the ecliptic. Quite often the asteroid belt is depicted as appearing to be crowded (see above picture), however individual asteroids are spaced quite far apart.
   While the greater majority of asteroids are located within the main asteroid belt, there are two areas along the orbit of Jupiter where there are a collection of asteroids known as the Trojan asteroids. They are located approximately 60° ahead and behind Jupiter and orbit the Sun with Jupiter. Trojans have darker surfaces than main belt asteroids and are more difficult to detect, but it is thought that there may be as many Trojan asteroids as there are within the main belt.
   In the past, the asteroid belt probably contained enough material to form a small planet. However, the gravity from the largest planet, Jupiter, and its orbital period around the Sun, set up orbital resonances with many of the asteroids during the formation of the solar system, disrupting their orbits and preventing the formation of a planet. Many of these disrupted objects were pulled from the main asteroid belt and became meteoroids with their own orbits around the Sun, or were ejected from the solar system, or simply crashed into other planets or moons. Some of these we now know as NEO, Near Earth Objects, and these represent potential impacts with our planet if orbital circumstances are right.

Wikipedia links to 17 Asteroid Missions.

Click here to go to the Qué tal in the Current Skies web site for more observing information.