Rings and Comets Flashcards
What is meant by occultation?
When a body moves in front of another – like the Moon passing over a planet.
What is meant by ‘Greatest elongation’?
The remaining angle between Sun, Earth and Planet when the planet is at a right-angle to the Sun and the Earth.
Give three uses of space probes.
Any three from:
Probes such as those carried by Cassini- Huygens onto Moons such as Titan, to measure atmosphere, beam back images, record sounds etc.
Spectrometers to record chemical composition of planets (or of material around them such as Saturn’s rings) e.g. Cassini-Huygens.
Missions to capture comet material and send back to Earth for analysis e.g. Stardust.
Rovers that explore surface and can examine rocks and other finds e.g. Mars Exploration Rovers.
Landers that can examine and run basic experiments and beam back results to Earth e.g. Phoenix (Mars).
Radar probes that can show geographical features underneath the clouds e.g. Magellan.
Who discovered Saturn’s rings?
Christian Huygens. Not Galileo, who first OBSERVED them.
How were Uranus’s rings discovered?
Scientists detected blips of darkness from the occulted star before and after Uranus passed in front of it suggesting Uranus had a series of thin rings surrounding it.
How were Jupiter and Neptune’s rings discovered?
By the Voyager space probes.
What happens when a comet approaches the Sun?
Some water-ice evaporates and jets of gas and dust produce a spherical coma around the nucleus.
Describe and explain a comet’s dust tail.
It forms in the opposite direction to the Sun and is caused by radiation pressure. It is very bright because of the reflection of ice particles.
What is the ion tail of a comet?
Caused by the solar wind, the ion tail is coloured and straighter than the dust tail.
How far away is the Kuiper Belt?
About 100-1000AU
