<p>If you want to know the number of <code>spectroscopically confirmed</code> galaxies then the number given by UV-D is roughly correct.</p>

<p>But the actual number of galaxies that have been observed is order of magnitudes larger. </p>

<p>The case I know is the Sloan Digital Sky Survey 3 (SDSS3):
they observed about a third of the sky using five different filters between optical and near infrared. Of all the objects detected <code>208,478,448</code> are galaxies. And of those 1.5 to 2 millions will have the spectrum measured by mid next year. 
<a href="http://www.sdss3.org/dr8/scope.php">More info here</a></p>

<p>To these number you have to add the galaxies observed by surveys in different areas of the sky, deeper that SDSS (which means that they can seen fainter and/or more fare away objects). </p>

<p>By the way, if memory does not fail me, estimates gives about 10^10 galaxies in the observed universe</p>

CC BY-SA 3.0
2013-09-25T08:00:36.880Z
2013-09-25T08:00:36.880Z
Francesco Montesano
<p>I know Andromeda is our nearest galaxy. But how many known galaxies have been discovered and what are they?</p>

<galaxy>
How many galaxies have been discovered?
Unicorn
# How many galaxies have been discovered?

(Asked by: username_0 on 2013-09-25)

I know Andromeda is our nearest galaxy. But how many known galaxies have been discovered and what are they?

**Tags:** galaxy

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## 1 answers

### Answer by username_1 on 2013-09-25. Score: 12

If you want to know the number of `spectroscopically confirmed` galaxies then the number given by UV-D is roughly correct.

But the actual number of galaxies that have been observed is order of magnitudes larger.

The case I know is the Sloan Digital Sky Survey 3 (SDSS3):
they observed about a third of the sky using five different filters between optical and near infrared. Of all the objects detected `208,478,448` are galaxies. And of those 1.5 to 2 millions will have the spectrum measured by mid next year.
[More info here](http://www.sdss3.org/dr8/scope.php)

To these number you have to add the galaxies observed by surveys in different areas of the sky, deeper that SDSS (which means that they can seen fainter and/or more fare away objects).

By the way, if memory does not fail me, estimates gives about 10^10 galaxies in the observed universe


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