When we picture the sun, what comes to mind is a massive ball of light 93 million miles away. However, in reality, its atmosphere extends outwards far beyond its surface. The Southern and Northern lights that we see on Earth are proof that we orbit inside the Sun’s atmosphere. Auroras have been observed on planets as far away as Neptune. The outer solar atmosphere is thought to extend to about 10 billion miles – more than twice the distance between the Sun and Pluto!
3. Iapetus: The mysterious moon of Saturn
One of Saturn’s moons, Iapetus, was discovered in 1671, but more recent discoveries about the moon have been baffling astronomers all over the world. Iapetus is the third-largest natural satellite of Saturn, but it raises the most questions. Firstly, one side of this moon is darker than the other, and the color difference is striking. This is mainly attributed to the fact that its orbit around Saturn allows one of its hemisphere to be more illuminated than the other.
Secondly, it is the only body in the Solar System that is not in hydrostatic equilibrium. This means that its shape is non-spherical, and not just because of irregularities in its thin crust. Iapetus peaks at its equator by a height of about 20km above the surrounding plains. This ridge gives it a unique shape, so Iapetus actually resembles a walnut more than a moon.