Artist’s logarithmic scale conception of the observable universe. Galaxies give way to large-scale structure and the hot, dense plasma of the Big Bang at the outskirts. Trying to figure out how many galaxies exist within the Universe is one of the great cosmic quests of our time. (WIKIPEDIA USER PABLO CARLOS BUDASSI)

This Is How We Know There Are Two Trillion Galaxies In The Universe

Hubble, even at its best, only reveals perhaps 10% of what’s out there. Here’s how we get the rest.

When you gaze up at the night sky, through the veil of stars and the plane of the Milky Way close by, you can’t help but feel small before the grand abyss of the Universe that lies beyond. Even though nearly all of them are invisible to our eyes, our observable Universe, extending tens of billions of light years in all directions, contains a fantastically large number of galaxies within it.

Just how many galaxies are out there used to be a mystery, with estimates rising from the thousands to the millions to the billions, all as telescope technology improved. If we made the most straightforward estimate using today’s best technology, we’d state there are 170 billion galaxies in our Universe. But we know more than that, and our modern estimate is even grander: two trillion galaxies. Here’s how we got there.

Our deepest galaxy surveys can reveal objects tens of billions of light years away, but even with ideal technology, there will be a large distance gap between the farthest galaxy and the Big Bang. At some point, our instrumentation simply cannot reveal them all. (SLOAN DIGITAL SKY SURVEY (SDSS))

In an ideal world, we’d simply count them all. We’d point our telescopes at the sky, cover the entire thing, collect every photon emitted our way…