Questions About Saturn
Download Questions about Uranus (all answers found on this page)
- Uranus cannot be seen from the Earth without a telescope.
- The seventh planet from the Sun, it was not known in ancient times, unlike the planets from Mercury to Saturn.
- Uranus was first seen by William Herschel in 1781 during a survey of the sky using a telescope. In 1782 George III appointed Herschel as Astronomer Royal.
- William Herschel was born in Hanover, Germany. He moved to England in 1757 in order to follow a career as a musician but after buying a book on astronomy he became interested only in watching the sky.
- Herschel also discovered 2 of Uranus’ moons with a larger telescope.
Figure 1: Uranus and its moon Ariel, the white dot, and Ariel’s shadow.
- Uranus is one of the “gas giants”, the four outer planets which are entirely composed of gas, Jupiter, Saturn, Uranus and Neptune.
- Most of the centre of Uranus is a frozen mass of ammonia and methane, which gives it the blue-green colour. The atmosphere also contains hydrogen and helium.
- Uranus orbits the Sun lying on its side and takes 84 years to complete one orbit. The Earth goes round the Sun in 365 days, one year.
- Because Uranus is lying on its side as it orbits the sun, for nearly a quarter of its orbit one pole of the planet is in complete darkness.
- Uranus takes 17.9 hours to turn once on its own axis, faster than the Earth, which takes 24 hours and gives us the change from day to night.
- Uranus was the ancient Greek God of the heavens whose sons were the Giants and Titans.
- Uranus is the smallest of the four “giants”, but is still several times larger than the Earth. It has a diameter of 29297 miles, or 47, 150 kilometres, compared to the Earth’s diameter of just under 8000 miles, or 12,760 kilometres.
- Uranus is 1782 million miles, or 2869 million kilometres from the Sun. Figure 1 does not show the distances from the Sun to scale, but Figure 2 lets you have an idea of how much further Uranus is from the Sun than the Earth.
- Distances in the Solar system are measured in Astronomical Units (AU), with the Earth’s distance from the Sun being 1 AU. Uranus is 19.2 AU from the Sun. Figure 2 shows the distances of the first seven planets from the Sun, measured in AU.
- In 1977 Uranus passed in front of a star and astronomers observing the planet through giant telescopes saw nine rings around the planet. These are very faint and not easily seen, unlike the rings around Saturn.
- Photographs sent back by the Voyager spacecraft in the 1980s showed a further two rings round the planet.
- The Hubble Space telescope found two more very faint rings, very distant from the planet, between 2003 and 2005, so we now know of a total of 13 rings.
- Scientists do not yet understand exactly what causes these rings or exactly what they consist of.
- From the time when Uranus was first observed scientists noticed that at certain points in Uranus’ orbit the planet was being pulled further out into space.
- In the 19th century certain astronomers worked out that this must be because of the pull of gravity from another planet beyond Uranus.
- By making mathematical calculations based on the observations of Uranus, two astronomers, Adams and Le Verrier, identified where this other planet must be.
- The planet which was exerting a gravitational pull on Uranus was Neptune, 10.9 AU further out into space.
Nineplanets, by Bill Arnett
Alternate Images of Uranus