Whizzing through the solar system from inside to outside. There are lots of different ways we explore space, starting with simple light telescopes, radio telescopes, ones out in space, spacecraft flying past and even landing.
- The Sun or Sol, that’s why it’s the Solar system! The nuclear furnace that powers the whole system.
- Mercury is the innermost planet, the smallest and densest. It also has the oldest surface, as it has no erosion to remodel it. This picture comes from the mission to orbit and study Mercury MESSENGER, run by NASA and Johns Hopkins University.
- Venus is close in size to the earth, but is the hottest planet in the solar system. It is the victim of a runaway greenhouse effect and rains sulfuric acid. It is difficult to see the planet because of clouds, this image is a composite of radar mapping by the Magellan spacecraft and Arecibo on earth. The colours show the elevation, with several highlands visible.
- Earth, what more can I say? Only planet with liquid water, only planet with a single moon, only planet with humans. Enjoy.
- Near Earth Objects, the NEOs. These are the asteroids that don’t stay put nicely in the asteroid belt but loop in to the earth’s orbit. There’s a lot of jostling out there. There has recently been a mission to actually land on one of the NEOs, Eros. This photo was taken 250m above the surface of Eros by NEAR Shoemaker before it landed.
- Mars is the most exciting planet in the sense that it’s the one we have most chance of getting to and even finding life. There are two rovers that were supposed to last about 3 months and travel 1km at most, 6 years later they are still going and have notched up 12km and 20km. This photo was taken actually on the planet’s surface by Opportunity. Stop and think how amazing that is – to directly see the surface of another world.
- The Asteroid belt lies between Mars and Jupiter and isn’t anywhere near as exciting as they look in the movies, sorry. They’re actually so far apart that you wouldn’t even notice you were flying through it. The largest asteroid we know of is called Ceres, it is officially a dwarf planet 950km across, big enough for its gravity to have pulled it into a sphere. This photo is taken by the Hubble Space Telescope.
- Jupiter, the biggest planet, and with so many moons almost a solar system in its own right. It is a gas giant, it probably has a relatively small rocky core that is surrounded by metallic hydrogen. The core would still be far bigger than the earth even if it is a tiny fraction of Jupiter itself. This is a constructed montage of Jupiter with the four big Galilean moons – Io, Ganymede, Europa and Callisto.
- Saturn, which everyone knows for the rings. They are made of particles of ice, dust and rocks and orbit the planet. Another gas giant a bit smaller than Jupiter, it also has many moons throughout the rings.
- Uranus has suffered a massive catastrophe at some time in the past, knocking it so it orbits almost on its side along with its rings and moons. It was the first planet discovered with a telescope and has a complex cloud system with water clouds thought to be at the lowest level. This photo is from the Hubble Space Telescope and shows bright clouds as well as the rings and 10 of the 17 known moons, some are very faint.
- Neptune was predicted before it was found. As Uranus was studied it wasn’t orbiting the way it was predicted, and it was proposed that another planet’s gravity might be pulling it. Neptune was found very close to where it was expected. It has very active weather systems with several layers of clouds.
- The Kuiper Belt has become much more famous now that Pluto has been downgraded. It is no longer classed as a planet but is a dwarf planet, one of the largest in the Kuiper Belt. This is basically an asteroid belt spread out beyond the planets. There is at least one other body as large as Pluto out there, and Pluto and its moon Charon, shown in this picture, are often thought of as a double planet system because Charon is half its size and they orbit around a point between them. This photo was taken by the Hubble Space Telescope, it is the equivalent of seeing a baseball 40km away. Interaction between the Kuiper Belt and Neptune have thrown some objects out further, forming the Scattered Disk. This includes Eris, the largest dwarf planet which is larger than Pluto.
- The Oort cloud is a vast spherical halo around the sun, the edge of the solar system and the birthplace of comets. Sedna has only recently been discovered and has been described as the most important recent discovery in the solar system because it could tell us so much. It has a highly elliptical orbit, it could be an extremely distant Scattered Disk Object or the first known member on an inner Oort cloud.
These pictures give an idea of the scale of the solar system and are a good way to round off the tour. Clockwise from the upper left, the inner solar system and asteroid belt. In the second panel are the outer planets, Kuiper belt and Sedna. The third panel shows the peculiar orbit of Sedna, then the final picture shows where the Oort cloud is thought to be.
I hope you’ve enjoyed our tour 🙂
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