Image of the main asteroid belt and the Trojan asteroids
Asteroids are mostly small Solar System bodies composed mainly of rocky and metallic non-volatile minerals.
The main asteroid belt occupies the orbit between Mars and Jupiter, between 2.3 and 3.3 AU from the Sun. It is thought to be remnants from the Solar System’s formation that failed to coalesce because of the gravitational interference of Jupiter.
Asteroids range in size from hundreds of kilometers across to microscopic. All asteroids save the largest, Ceres, are classified as small Solar System bodies, but some asteroids such as Vesta and Hygieia may be reclassed as dwarf planets.
The asteroid belt contains tens of thousands, possibly millions, of objects over one kilometer in diameter. Despite this, the total mass of the main belt is unlikely to be more than a thousandth of that of the Earth. The main belt is very sparsely populated; spacecraft routinely pass through without incident. Asteroids with diameters between 10 and 10-4 m are called meteoroids.
Ceres
Ceres (2.77 AU) is the largest body in the asteroid belt and is classified as a dwarf planet. It has a diameter of slightly under 1000 km, large enough for its own gravity to pull it into a spherical shape. Ceres was considered a planet when it was discovered in the 19th century, but was reclassified as an asteroid in the 1850s as further observation revealed additional asteroids.
Asteroid groups
Asteroids in the main belt are divided into asteroid groups and families based on their orbital characteristics. Asteroid moons are asteroids that orbit larger asteroids. They are not as clearly distinguished as planetary moons, sometimes being almost as large as their partners. The asteroid belt also contains main-belt comets.
The inner Solar System is also dusted with rogue asteroids, many of which cross the orbits of the inner planets.
III. Answer the questions:
1. What is the Inner Solar System?
2. Where is it located?
3. How many components are there in the Inner Solar System?
4. What terrestrial planets are located in this region of the Solar System? Make a list of them.
5. What are the general characteristics of these planets?
6. What planet is the largest and smallest in the Inner Solar System?
7. Does Mars or Mercury have two satellites? Make a list of them.
8. There are three planets with the substantial atmosphere in the Inner Solar System, are not there?
9. What are the asteroids? How did they form?
10. Where is the main asteroid belt located?
|
|
|
11. What can you tell about the sizes of the asteroids and asteroid belt?
12. Which asteroid is the largest?
13. Are the asteroids single objects or they are subdivided into some groups?
IV. Do you agree or disagree with the following statements? Prove your position.
1. The Inner Solar System is the group of terrestrial planets located very far from the Sun.
2. The four inner or terrestrial planets have dense, rocky compositions, few or no moons, and no ring systems and some of them have substantial atmosphere.
3. The terms inner planet and inferior planets are the same.
4. Mercury is the farthest and largest planet of the Inner Solar System.
5. Venus and Mars have the same size.
6. The Earth is the only planet with the hydrosphere and life on it.
7. Mercury has two natural satellites.
8. Venus is the hottest planet, with surface temperatures over 400 °C.
9. Asteroids are mostly small Solar System bodies composed mainly of icy and volatile minerals.
10. The main asteroid belt occupies the orbit between Pluto and Neptune.
11. Asteroids range in size from hundreds of kilometers across to microscopic.
12. Vesta and Hygieia are the largest asteroids.
13. Asteroids in the main belt are divided into asteroid groups and families.
14. There are no other objects except asteroids in the asteroid belt.
Дата добавления: 2015-12-21; просмотров: 16; Мы поможем в написании вашей работы! |
Мы поможем в написании ваших работ!