The Scale of the Universe: From Planets to Galaxies

0:00Just how big is the universe?

0:03Our planet, Earth, is about 12,700 kilometres across.

0:09Zoom out, and Earth is a tiny dot orbiting the Sun, about 150 million kilometres away.

0:17The Sun and everything that orbits it, including eight planets, make up the solar system.

0:24Beyond the solar system, distances are so huge that we measure them in light-years.

0:30One light-year is how far light travels in one year, about 9.5 trillion kilometres.

0:37Zoom out again, and the Sun is just one of billions of stars in our galaxy, the Milky Way.

0:45The Milky Way is about 100,000 light-years across.

0:50Zoom out once more, and the Milky Way is one of billions of galaxies in the universe.

0:57The nearest large galaxy, Andromeda, is about 2.5 million light-years away.

1:03Each step out is far, far bigger, so these pictures are not drawn to scale.

1:10So Earth is a tiny part of the solar system, the Milky Way and a vast universe of galaxies.