Category Archives: Universe

All space stuff is far away. But NGC 4889, also known as Caldwell 35, is really, really, really far away: 300 million light years. That means the light from this galaxy that reaches Earth today is 300 million years old.

This largest known galaxy, IC 1101, contains 100 trillion stars, almost 1,000 times more than the Milky Way.

Virgo A, also called M87, has everything a self-respecting galaxy needs: a couple trillion stars, a supermassive black hole and a few thousand globular star clusters. Our own Milky Way with its few billion stars looks quaint in comparison.

Andromeda is 2.5 million light years away from us, about 12 Milky Way diameters. Since light takes 2.5 million years to pass between the two galaxies, if some super high—tech Andromeda alien is viewing us with a telescope right now, they’re seeing a bunch of Austrolopithecus walking around being unappealing.

At one billion years away, this cluster hides away the largest galaxy known, IC 1101, in an amount of dark matter equivalent to more than a hundred trillion Suns. If we were to take Abell 2029 as a representative sample of the Universe, 70 to 90% of it would be cold dark matter.

If the observable Universe is our world and the Milky Way is our house, the local group is our neighborhood. There are at least 80 galaxies in the neighborhood, but the Milky Way and Andromeda are the two biggest, with all the rest swarming around them like paparazzi.

The Local Group is our pocket of the Universe, the limit we will never cross. But if we took the DNA of all the humans present on Earth in 2021, untangled and put these strands together into one long ribbon, it would span one and a half times across the Local Group. Bunched up tightly together, our species’ collective DNA could fill a cube with sides the length of a football field.

Clusters are families of entire galaxies, that unlike real families aren’t bound together by blood, petty feuds and love, but gravity. They contain enough matter to pull even distant family members toward them — again, with gravity, not a bad conscience and wedding ceremonies like real families do. Hanging out 60 million light years away, you could call this cluster of galaxies the next neighborhood over from ours.

If the observable Universe is our world, the Local Group of galaxies our neighborhood, and the Milky Way our house, the Virgo Supercluster is our city. The “city” has more than 700 galaxies in 100 Local Group “neighborhoods”, and stretches 110 million light years across. To put that in perspective, if the observable Universe is a sphere with a diameter of 1 km, large enough to contain the tallest skyscrapers, the Virgo Supercluster is a sphere 1.47 m across, about the height of a child. On that scale, the Milky Way is a tiny disk 2 mm across.

Space looks calm, but actually our own galaxy, the Milky Way, is traveling through the cosmos at 2.2 million km an hour. This is a bit of a mystery. According to our ideas about the Big Bang, everything in the Universe should be flying apart at similar speeds. If everything is moving at similar speeds, it should look like nothing is really moving at all. When some objects seem to be moving faster than others, it’s usually because clumps of matter like galaxy clusters are exerting an additional gravitational pull. But we know of nothing close to the Milky Way that explains its drift — we just know that something must be causing it. Astronomers named the mysterious clump of matter we haven’t found yet “The Great Attractor”.