If you're interested in astronomy and planetary science, chances are you will have come across the term 'Astronomical Unit', or AU, before.
The enormous distances in our Solar System make it difficult for most of us to get our heads around. To discuss these vast distances, astronomers use the Astronomical Unit, AU.
One Astronomical Unit is the average distance between Earth and the Sun ('average', because the distance between Earth and the Sun varies throughout the course of Earth's orbit).
1 Astronomical Unit is equal to about 150 million kilometres (93 million miles).
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Solar System planets' distance in AU
When discussed in terms of the Astronomical Unit, our nearest planets are practically on top of each other:
- Mercury at 0.4 AU
- Venus at 0.7 AU
- Earth at 1 AU
- Mars at 1.5 AU.
The Solar System's Goldilocks Zone sits within the narrow band around Earth.
Beyond here, things get large very quickly.
- Jupiter at 5.2 AU
- Saturn at 9.6 AU
- Uranus at 19.2 AU
- Neptune at 30 AU.
Yes, the most distant Solar System planet orbits at an eye-opening distance, 30 times that between Earth and the Sun.
Now, think about our little Solar System being over 250,000 AU from our nearest star.
Our Sun, in turn, is just one of many tucked away in a small corner of the Milky Way, which is only one of many galaxies that make up the known Universe.
It can make your head spin.
This article was taken from Big Ideas Little Pictures and Sketchplanations by Jono Hey.
