3.5Unit 6: Light and objects in space
Rocks in space — Cambridge Checkpoint Physics 0893 Revision Notes & Topical Questions
5 min read 9 parts Lesson 8 of 8 1 quiz
Lesson summary
3.5 Rocks in space — CHECKPOINT PHYSICS 0893 notes: Describe asteroids, where they are found and how they relate to the formation of the Solar System and impacts on Earth.Asteroid = a rocky object that orbits the Sun and is smaller than a planetOrigin — scientists believe asteroi…
- Asteroid belt
- Sample return
- Tidal forces
- Small and fast spinning
- Conclusion
- Large impacts
Part 1 of 7What asteroids are
Asteroid
Asteroid a rocky object that orbits the Sun and is smaller than a planet
Origin
- Origin scientists believe asteroids are rocks left over from the formation of the Solar System
Size
- Size they range from about 2 m across up to 975 km
Shape
- Shape most are irregular, similar to the shape of potatoes
Number
- Number there are millions, and some have been given names
Part 2 of 7The asteroid belt
Location
- Location most asteroids orbit the Sun between the orbits of Mars and Jupiter
Asteroid belt
Asteroid belt this region of the Solar System
Part 3 of 7Ceres
Ceres
Discovery
- Discovery found in 1801 and first thought to be a new planet
Name
- Name since it looked much smaller than a planet, the term asteroid was introduced
Size
- Size it is round, 975 km across, the largest asteroid
Structure
- Structure it is covered with craters and has a core, mantle and crust like some planets
Origin
- Origin scientists think it would have become a planet if it had continued to grow
Part 4 of 7Itokawa
Itokawa
Size
- Size about 530 m long and 250 m wide
Sample return
- Sample return in 2005 a spacecraft collected samples from its surface
Structure
- Structure it appears made of lumps of rock from other bodies broken by impacts
Gravity
- Gravity the force holding the lumps together is weak because the asteroid is small
Tidal forces
- Tidal forces passing a large object such as a planet can change its shape
Part 5 of 7Single-rock asteroids
Small and fast spinning
- Small and fast spinning gravity is too weak to hold separate pieces together
Conclusion
- Conclusion these asteroids are made of a single piece of rock
Part 6 of 7Asteroids and Earth
Large impacts
- Large impacts a large asteroid hits Earth on average every 130 000 years
Small impacts
- Small impacts smaller asteroids hit very often but break up in the atmosphere
Reason 1
- Reason 1 the Earth exerts a strong force of gravity on passing objects
Reason 2
- Reason 2 many asteroids have orbits that pass close to Earth
Part 7 of 7Tunguska explosion evidence
Event
- Event a very large explosion above the forest at Tunguska, Russia, on 30 June 1908
Effects
- Effects it flattened trees over 2000 km² and was heard over 800 km away
Evidence
- Evidence fallen trees point outwards from a central position and small rocky fragments with signs of falling at high speed were found
Missing evidence
- Missing evidence no metal parts were found and Tunguska is far from tectonic plate boundaries
Likely cause
- Likely cause an asteroid or comet impact, with the evidence best supporting a rocky object
Key terms
| Term | Meaning |
|---|---|
| Asteroid | Rocky object orbiting the Sun, smaller than a planet. |
| Asteroid belt | Region between Mars and Jupiter with most asteroids. |
| Ceres | Largest asteroid, 975 km across. |
| Crater | Bowl-shaped hole made by an impact. |
| Solar System | The Sun and the objects that orbit it. |
Avoid these mistakes
1
Thinking asteroids are small planets — they are rocky objects smaller than planets.
2
Thinking all asteroids are round — most are irregular.
3
Thinking asteroids orbit the Earth — they orbit the Sun.
4
Thinking asteroids never hit Earth — small ones often hit and large ones occasionally.
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