Galaxy Zoo 2 - Top Photo

Frequently Asked Questions

Q. Why can’t I zoom in or out?

A: For now, we need to make sure that each of our classifiers is seeing exactly the same image. We’ll be experimenting with adding this feature in the future.

Q. How can I find out more about a particular galaxy?

A: The previous version of the site allowed users to look at data provided by the Sloan Digital Sky Survey while classifying; this caused confusion because we only want you to classify according to what you can see. Let computers take care of the rest! However, you can now find a link to this extra data on the "My Galaxies" page which is linked from the main analysis page if you’re logged in.

Q. How can I change a classification?

A: If you’d like to change your mind during classifying a particular galaxy, you can return to any point in the sequence of questions by just clicking on the small buttons under where it says 'Please click an image below to return to an earlier point in the classification'. Once you’ve finished a galaxy, and your classification has been submitted to our database, then you can’t change it, but don’t worry – we compare classifications from multiple users so someone else will correct any mistakes.

Q. Can I redo a classification?

A: It is not possible to redo a classification, as we want each one to be independent. Allowing classifications to be replaced would open up the possibility of classifiers discussing objects and changing their classifications to agree with one another. This would reduce our ability to understand the uncertainties on the classifications. However, don't worry about our final results: each galaxy has been looked at by many people, so on average the classification is likely to be correct, and occasional mistakes don't matter.

Q. Why do you need many people to look at each galaxy?

A: If one person does the classification – even if they’re an expert astronomer – then anything odd or interesting can be blamed on them. With multiple independent classifications we can statistically calculate the confidence in our classification, and that’s a large part of the power of Galaxy Zoo.

Q. I have noticed the colours seem to vary between spirals and ellipticals. Can we use this to help with our classifications?

A: Well spotted. Massive stars are blue, and also short lived (by astronomical standards, anyway) so we only see them where star formation has occured recently. That tends to be in spiral galaxies, but beware! We're trying to classify galaxies by shape, not by colour; one of the major results from Galaxy Zoo is that colour and shape are more independent than people believed, so we need to be careful. Classify what you see and ignore the colours!

Q. Why don’t you just show us black and white images, then?

A: We tested for any difference in classifications between showing people colour and showing people monochrome images in the original Galaxy Zoo, and found that it was only small. We also discovered that our users really like looking at coloured galaxies, and we aim to please.

Q. There are loads of galaxies in this image

A: Please always classify the one that’s right in the middle, but use the ‘is there anything odd’ question and the tag system (when it is live) to tell us about anything interesting that catches your eye.

Q: You haven't answered my email!

A: Sorry. Really, we're sorry. The Team is growing, but is still small and busy, and we're rushed off our feet making the most of your results and developing the Zoo. You might find an answer on the forum — and that's also the best way to grab our attention.

Q: Can I name my galaxies?

A: Sadly, astronomers are very attached to catalogue numbers, so there's no way we can officially name them. Sorry!

Q: If an object is red then is it moving away from us?

A: Objects that move away from us appear redder than if they were stationary. Likewise, objects get bluer if they move towards us. This is called the Doppler effect. But that does not mean that all red things are moving away from us, because somethings just are red anyway (like some stars) and some galaxies emit blue light, for example. So we have to be careful with colours! You actually need to look at their spectrum to be sure if it is moving away from you.

Q : What happened to the original Galaxy Zoo site?

A: It's still alive, here, so if you're feeling nostalgic you can go and play. But, we're preparing the data for a final release to the astronomical community (and everyone else), so no clicks you make now will be recorded in our database.

Q : What happened to the classifications we did during the beta phase of Galaxy Zoo 2?

A: They're safe! In fact, the results were impressive, so it's thanks to all of the people who took part that we were able to launch Galaxy Zoo 2. The beta results will be compared with the results from Galaxy Zoo 2 and combined to form the final data set. We'll try and make them visible in "My Galaxies" soon.

Q: How do you select the galaxies for Galaxy Wars?

A: We compare galaxies of similar size, distance and brightness; you can read more about Galaxy Wars here :

Q: Galaxy Wars asks me to compare a galaxy with itself! What do I do?

A: Oops. Sorry - this is a known bug in the software. Just click either of the galaxies and move on, safe in the knowledge that there wasn't a wrong answer.

Q: Why are some of the images strangely coloured?

A: These are from an area of the sky known as 'Stripe 82'. The telescope made repeated visits to this part of the sky, and we can add together the images taken on each of these occasions to produce a single image which should show more details than any single one. We're hoping to compare classifications of these images to those of the normal ones to see how your classifications have been affected by the quality of the images, and of course, to study these galaxies in more detail.

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