What is below Earth? More space

The key to answering a question about orientation in space is perspective. Because what is up or down or flat or not depends on many things. By Jeff Moersch

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Travelling in any direction away from Earth, you'll eventually encounter galaxies with their own up-and-down orientations. A side view of galaxy NGC 4217 taken by the Hubble space telescope shows how all the stars and their planetary systems lie on one plane.

(NASA Hubble and NASA/ESA)

If you've seen illustrations or models of the solar system, maybe you noticed that all the planets orbit the sun on more or less the same plane, travelling in the same direction.

But what is above and below that plane? And why are the planets' orbits aligned like this, in a flat pancake, rather than each one travelling on a completely different plane?

I'm a planetary scientist who works with robotic spacecraft such as rovers and orbiters. When my colleagues and I send them out to explore our solar system, it's important for us to understand the 3D map of our space neighbourhood.

Earth's gravity has a lot to do with what people think is up and what is down. Things fall down towards the ground, but that direction depends on where you are.

Imagine you're standing somewhere in North America and point downwards. If you extend a line from your fingertip all the way through the Earth, that line would point in the direction of "up" to someone on a boat in the southern Indian Ocean.

In the bigger picture, "down" could be defined as being below the plane of the solar system, which is known as the ecliptic. By convention, we say that above the plane is where the planets are seen to orbit counterclockwise around the sun, and from below they are seen to orbit clockwise.