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    Use the Search box below to find doubles by popular name, RA, or telescope size. For example, a search on "15h" will find all doubles we've reported on that have an RA of 15 hours. A search for "60mm" will find all doubles where we used that size telescope.

Our favorite double!

Click for larger image.

This is a picture of our favorite double. Charming, isn’t it? But can you guess which one it is?

If you’re uncertain and want a hint, go here. If you think you know, go here to discover if you are correct.



HINT – we think it’s your favorite double too!

Think you know the answer now? Go here to discover if you are correct. Or if you want a second hint, go here.



HINT: Smile, you’re on candid Camera – Messenger style!

Still stumped, or just want to confirm your answer? Go here!

Yes, that’s us – the Earth and Moon as seen by the Messenger spacecraft from 114 million miles away.

To put that distance into perspective, the Earth and Sun are separated by about 93 million miles. Light would take a little more than 10 minutes to travel from us to the spot from which this picture was taken by the Messenger spacecraft! (Photo Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.)

When we look at double stars we are always interested in getting a clean split – and frequently we like to know what the real distance between the two stars is. So what’s that black gap we see between Earth and the Moon? Well, on average that gap represents about a quarter million miles.

Whoa! Wait a minute. Let’s look at that picture again!

Click for larger image.

The Earth is about 8,000 miles in diameter. How could that gap possibly be a quarter million miles? Good question. And all we can suggest is that the Earth and Moon are dazzling a camera just the way a bright star dazzles our telescopes. In fact, we frequently find it difficult to see a dim star next to a small one because the brighter star is filling the gap between the two with its brilliance – not with its actual bulk. In fact, stars show no disc at all, even in the largest earth-bound telescopes. They are just point source of light. But the smaller the telescope, the bigger the apparent disc a star makes. Think about it and you’ll understand why we need to use large telescopes to “separate” some doubles.

Now that’s the kind of double “star” that can really make you think!

Oh, so you think you weren’t there when this family portrait was taken? Well, it’s possible you weren’t born yet. But the picture was taken May 10, 2010. So how did you learn to use a computer and read at such a young age? Chance are, you’re “in” the picture, though granted, you may be out of sight on the other side of our planet. But even if you’re an astronaut, you’re “in” this shot.

For a neat collection of other Earth-Moon photos from a distance, go here

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