On Tuesday, Venus will pass in front of the sun for the last time until 2117.
Southern Stars Group, LLC, makers of SkySafari for iOS wants people to use their iPhone or iPad cameras to capture the transit and have a chance to win an iPad, iPod touch, or a Samsung Galaxy tablet (which most of our readers would probably pass on).
To enter, here's the catch, you must own a copy of one of the editions of SkySafari, which is on sale for this event starting at US $0.99. Rules for the contest can be found on the Southern Stars website.
Contest aside, this is a good excuse to get SkySafari if you don't have it already. It's a great way to get out under the summer night skies and see what is up there. At transit time, which is of course a daytime event, you'll be able to see a simulation of what's happening in real time. Let me emphasize that just like an eclipse, you DON'T want to look at the sun. Make a pinhole camera, or get some solar viewing glasses, and don't look at the sun with a telescope or binoculars unless those devices are properly protected. Frying your eye is simply no fun and can ruin your day.
Here's some NASA information about the transit and some general photography tips, although they don't apply specifically to your iPhone camera. If you want even more information, the Bad Astronomy website has a good collection of facts and tips.
Enjoy the transit, if you can see it. It will be visible in about 2/3 of the world, so if the weather cooperates you should have no trouble seeing Venus glide in front of the sun. Most of us won't have a chance to see the next transit, so good luck.
Check the gallery to see how SkySafari simulates the event.