Chapter 16 – The Planets. If you notice anything that looks wrong…. just let me know via the comments! 🙂
1. a) What is so unusual about the axial rotation of Venus?
Venus rotates the opposite way around than the other planets.
1. b) Why is it unlikely that Venus can support any form of life?
Venus cannot support life because it has a highly corrosive atmosphere.
1. c) What did Mariner 10 tell us about the surface of Mercury?
Mariner 10 told us that the surface of Mercury is very much like the surface of the Moon. Also that it has little atmosphere, but a large magnetic field.
2. a) Is the atmosphere of Mars as dense as that of the Earth, and what is its composition?
The atmosphere of Mars is less than that of Earth and it is mainly composed of Carbon Dioxide.
2. b) How did the Viking probes carry out their search for life on Mars?
The Viking probes landed on the surface of Mars and scooped up little samples of Martian soil and tested. They then sent back the results.
2. c) Why is it thought that there must once have been running water on Mars, even though there is none today?
Because the rocks on the surface of Mars contain elements, and show evidence of erosion, meaning there had to be some form of water there.
3. a) Describe the appearance of Jupiter as seen through a telescope.
Through a telescope, a slightly flattened disk can be seen, most likely yellow in colour. Then, there may be brighter areas of colour near the north and south. There is also the possibility of seeing the great red spot, if your telescope is powerful enough.
3. b) What is Jupiter’s Great Red Spot, and where on the planet’s disc would you find it?
The Great Red Spot is a large whirling storm that is bigger than Earth. It is a typical example of true Jovian weather. It can be found on the top half of Jupiter.
3. c) In what important way does Io differ from the other Galilean satellites of Jupiter?
It differs in its composition. Io is a very active planet, with volcanoes and a sulphur covered surface. The other three Galilean planets are all very icy and cold.
4. a) Why did some nineteenth-century astronomers believe that there should be a planet moving between the orbits of Mars and Jupiter?
They thought that there should be some kind of planet there because of Bode’s Law. A number existed in the pattern that had no planet equivalent so for a long time, astronomers looked for a non-existent planet.
4. b) Voyager 2 by-passed all four giant planets by using the gravity-assist technique. Explain what this means.
When Voyager 2 was sent, the gas giants were in the optimum position, where they were all in some kind of curve. the probe curved round in a loop, like a shell, using the gravitation fields of the planets to sling shot it to the next planet. This optimum position won’t occur again for over a century.
4. c) How was the position of Neptune worked out before the planet was actually identified?
Astronomers noticed that Uranus wasn’t moving as it should have been. Something was pulling it out of position and two men named John Couch Adams and Urbain Le Verrier realised that it must be a planet. Watching how Uranus moved, they calculated where this unknown planet would be, contacted observatories to see if it could be found; and it was found by Johann Galle and Heinrich D’Arrest from the Berlin observatory almost immediately.
5. a) Give a brief description of Saturn’s ring system.
The rings of Saturn are usually divided into three main bands. Two of these bands are the brightest and most visible, whilst the other is a semitransparent ban. The two brightest bands are divided from each other by Cassini’s Division, named so after the Italian astronomer who discovered it.
The rings have always been thought to be solid, but they are in fact clouds of icy particles; which range from the size of pebbles to large blocks.
5. b) What is unusual about the axial rotation of Uranus?
Uranus rotates horizontally. It spins from the bottom to the top, whilst all the other planets rotate from side to side.
5. c) Should Pluto be regarded as a true planet? If not, why?
Pluto should not be considered a planet, because it is not large enough, but also because it has an elliptical orbit. Occasionally it is not always the last planet, but is sometimes the second to last, leaving Neptune to be last.
Also because it has already been denominated to a dwarf planet.