Our own galaxy, the Milky Way, has a diameter of 87,400 light-years.
There are many questions about life, the Universe, and everything but today we’re focusing on just one: How many galaxies are there in the Universe?
Beyond the Moon, the Sun, and the other planets in our solar system lies galaxies – which, held together by gravity, are made up of gigantic collections of dust, gas, stars, other solar systems, and in most, black holes.
The makeup of a galaxy and the Universe has fascinated astronomers for century upon century and we’re still discovering new galaxies and expanding our knowledge of the known Universe day by day.
Given that we’re still learning more about the Universe, it’s almost impossible to answer with total clarity how many galaxies are out there. This hasn’t stopped scientists from trying to answer the question, however, and we now have a feasible estimate.
How many galaxies are there in the Universe?
Recent estimates tell us that there could be as many as two trillion galaxies in the observable Universe.
Two trillion galaxies is an estimate. Scientists haven’t sat there and counted every single galaxy they’ve spotted in the known observable Universe. Instead, they have studied small sections of the Universe (equivalent size of a pinhead held at arm’s length) and counted the galaxies in those fractions.
This method has given us a lower limit to the number of galaxies in the observable Universe (there is plenty that cannot be observed with current technology), which is estimated to be between 100-200 billion galaxies.
The two trillion number comes from an estimate based on 3D conversions of images from the Hubble Space Telescope and new mathematical models, expanding on the work which led astronomers to 100-200 billion before.
“This led to the surprising conclusion that in order for the numbers of galaxies we now see and their masses to add up, there must be a further 90 per cent of galaxies in the observable universe that are too faint and too far away to be seen with present-day telescopes”, explained NASA in 2016.
Theoretically, there could be an infinite number of galaxies, as the size of the Universe itself could be infinite.
What is the largest galaxy in the Universe?
The largest galaxy in the Universe is likely the ESO 383-76 supergiant elliptical galaxy. It measures 1,764,000 light-years in diameter and is found in the Centaurus Constellation, some 654 million light-years from Earth.
It is difficult to know what is the largest galaxy in the Universe, however, as we’re constantly learning more about space every day thanks to new technologies including the James Webb telescope.
As such, many different galaxies have been claimed to be the largest in the Universe, including the IC 1101 and Alcyoneus galaxies. The largest known spiral galaxy is the UGC 2885, meanwhile.
When you get to the largest barred spiral galaxy in the Universe, you find the NGC 6872 (the Condor Galaxy). It’s 522,000 light-years across from one point to another, which makes it over five times the size of the Milky Way.
The Condor Galaxy is located in the Pavo Constellation and it’s 212 million light-years away from the Earth. Its diameter between the points of its ‘arms’ is 522,000 light-years in total, and it has an isophotal diameter of around 717,000 light-years.
Read more:
- NASA’s James Webb telescope spots ‘sparkling’ galaxy that may contain the oldest stars ever seen
- Why do we think black holes are in the centre of galaxies?
- Do all galaxies spin in the same direction?
- Are there any stars between galaxies?
- How far would we need to travel to leave our Galaxy?