- Comets are balls of ice and dust.
- The comets have a elliptical orbit around the sun (an oval shape orbit.)
- When the comets get nearer to the sun there is more gravity so the is more energy making the comets move quicker.
- When the comets are heading for the sun the suns heat vaporises material from their surface creating a tail of debris.
- Asteroids are smaller than planets.
- They are made form the left over formation of the solar system.
- Most asteroids are found in the asteroid belt between Mars and Jupiter.
- When asteroids crash they can break apart and change orbit.
- The orbits of some asteroids cross the earths orbit.
- In the past when a asteroid has hit earth it has caused a dramatic amount of energy to be released affecting the earths climate.
- Scientist worry that if a asteroid was to hit earth-
1.The impact would form a crater which could trigger a ejection of hot rocks.
2.The heat would cause widespreed fires.
3.Sunlight would be blocked from the dust.
5.Could make whole species extinct also effecting other species.
Evidence that Asteroids have hit in the past
Evidence to show that asteroids have hit in the past is-
- craters have been found all over the planet
- there is layers of unusual elements found in the rocks
- there are changes found in rocks which could be lots of animals hit at once.
If asteroids in the asteroid belt bumped into each other they could join or shatter but because Jupiter has a strong gravitational pull it would stop them from joining as a planet.
- Also called shooting stars
- Fragments of dust and rock
- Much smaller than comets
- when they enter the earths atmmosphere they burn up becuase of the friction. Thsi means that they give out light making them easy to see.
- A NEO is a near earth object
- A near earth object is an asteroid or comet on a possible collision ourse with earth.
- Telescopes are used to observe NEOs so that the trajectories (possibke paths) can be determined.
- NEOs do pose a threat to humans although-
--We can survey the skies with telescopes to identify NEOs as soon as possible
--We can moniter NEOs with satellites
--We can deflect NEOs with an explosion if a collision is likley.