<p>(I'd make this a comment, but no reputation yet.)</p>

<p><a href="https://youtu.be/VVAKFJ8VVp4" rel="nofollow">Minute Physics</a> has a good video on this! Filtering light through any lens causes spikes that identify what kind of aperture was used. That looks like a Hubble picture because of the diamond spikes.</p>

CC BY-SA 3.0
2015-07-03T06:11:41.137Z
It is not to do with the circular aperture in the case shown.
ProfRob
CC BY-SA 3.0
2015-07-02T22:48:09.960Z
2015-07-02T22:48:09.960Z
Jareth Holt
<p>They are called <a href="https://en.wikipedia.org/wiki/Diffraction_spike">diffraction spikes</a>, and they're artifacts from a supporting structure inside a reflector-type telescope.</p>

CC BY-SA 3.0
2015-07-03T06:13:29.033Z
Maybe you could say how this leads to the pattern seen in this case. Might also be worth explaining why stars show diffraction spikes but galaxies do not.
ProfRob
CC BY-SA 3.0
2015-07-02T21:51:19.583Z
2015-07-02T21:51:19.583Z
Russell Borogove
<p>sometimes you can get these spike artifacts from the microlenses over the CCD's sensor array as well. </p>

<p>also if your CCD does not have antiblooming logic, a very bright star can cause neighboring pixels to saturate as they are being read out, leading to a "spike" only along the readout axis. here's a good document with some common artifacts, from the hubble team: 
<a href="http://www.stsci.edu/~levay/color/HandoutIIIc.pdf" rel="nofollow">HandoutIIIc</a>. </p>

<p>the spikes in the OP's image are likely caused by the spider vanes which hold the secondary mirror in place, as Russell says.</p>

CC BY-SA 3.0
2015-07-08T04:47:36.487Z
2015-07-08T04:47:36.487Z
pfile
<p>What causes the horizontal and vertical lines coming out of pictures of stars, instead of them simply appearing as circles? For example, this picture from Wikipedia: <img src="https://i.sstatic.net/tMp7E.jpg" alt="this picture">.</p>

CC BY-SA 3.0
2015-07-03T02:49:46.210Z
It should probably be noted that Fraunhofer diffraction is common in all kinds of photography, and is present in nearly every photo; though to greater degrees for photos with more closed apertures and far more obvious in high contrast situations provided by lights, like stars. Here is a [great question](http://photo.stackexchange.com/questions/6605/why-do-light-sources-appear-as-stars-sometimes/6609#6609) in the Photography stack exchange on the topic, and [another from Physics](http://physics.stackexchange.com/questions/35935/what-are-these-rays-that-appear-in-photograph-of-sun/35943#35943).
Mitch Goshorn
<star><photography>
What causes horizontal and vertical lines coming out of pictures of stars?
Tom
# What causes horizontal and vertical lines coming out of pictures of stars?

(Asked by: username_0 on 2015-07-02)

What causes the horizontal and vertical lines coming out of pictures of stars, instead of them simply appearing as circles? For example, this picture from Wikipedia: ![this picture](https://i.sstatic.net/tMp7E.jpg).

**Tags:** star, photography

> **Comments:**
> **username_1**: It should probably be noted that Fraunhofer diffraction is common in all kinds of photography, and is present in nearly every photo; though to greater degrees for photos with more closed apertures and far more obvious in high contrast situations provided by lights, like stars. Here is a [great question](http://photo.stackexchange.com/questions/6605/why-do-light-sources-appear-as-stars-sometimes/6609#6609) in the Photography stack exchange on the topic, and [another from Physics](http://physics.stackexchange.com/questions/35935/what-are-these-rays-that-appear-in-photograph-of-sun/35943#35943).  

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## 3 answers

### Answer by username_2 on 2015-07-02. Score: -1 | Accepted answer

(I'd make this a comment, but no reputation yet.)

[Minute Physics](https://youtu.be/VVAKFJ8VVp4) has a good video on this! Filtering light through any lens causes spikes that identify what kind of aperture was used. That looks like a Hubble picture because of the diamond spikes.

> **Comments:**
> **username_3**: It is not to do with the circular aperture in the case shown.  

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### Answer by username_4 on 2015-07-02. Score: 11

They are called [diffraction spikes](https://en.wikipedia.org/wiki/Diffraction_spike), and they're artifacts from a supporting structure inside a reflector-type telescope.

> **Comments:**
> **username_3**: Maybe you could say how this leads to the pattern seen in this case. Might also be worth explaining why stars show diffraction spikes but galaxies do not.  

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### Answer by username_5 on 2015-07-08. Score: 1

sometimes you can get these spike artifacts from the microlenses over the CCD's sensor array as well.

also if your CCD does not have antiblooming logic, a very bright star can cause neighboring pixels to saturate as they are being read out, leading to a "spike" only along the readout axis. here's a good document with some common artifacts, from the hubble team:
[HandoutIIIc](http://www.stsci.edu/~levay/color/HandoutIIIc.pdf).

the spikes in the OP's image are likely caused by the spider vanes which hold the secondary mirror in place, as Russell says.


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