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Comment by adv0r | Hacker News Reader

I don't really understand how come no-one was able to see it before... I don't know how it works, but since telescopes are looking for stars and stuff much more distant that mars, I was confident that they scanned the whole surface of neighbors planets decades ago... Some explanation?

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Things that could cause it to be missed:

* Angle of photography

* Time of day (direction of sunlight)

* Weather conditions

We often ignore problems that are "closer" to us. For example, the oceans on our own planet are still very much a mystery, yet we still look outward.

What specifically about our oceans are a mystery?

I'm just going to leave this right here. http://www.xkcd.com/1040/ It's a little bit of awesome.

There's a limit for how big/small an object you can see with a telescope due to diffraction. For instance, the Hubble telescope can not distinguish features on the moon that are less than approximately 100 meters. Obviously it gets much worse for Mars and the other planets.

Mars (according to Wikipedia) has a surface area of 144,798,500km^2. This thing is within an area of 35 meters^2 and I'm guessing it's not very flashy when viewed on a screen.

Needle in a haystack.

Heck, we're still finding strange things on the Moon:

http://www.lroc.asu.edu/news/index.php?/archives/277-Natural...

Earth-based telescopes can't be used to find an Apollo lander on the moon. It's just too damn far. A crater on Mars is a notch up from that.

Some great info about just why this is so impossible: http://calgary.rasc.ca/moonscope.htm

Interesting - how is it they can accurately target the puny "lunar laser ranging retroreflector array" but not see the landers?

The laser is 6.5KM wide when it reaches the moon. http://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment

Awesome! I see they lost the Soviet Lunokhod 1 array for nearly 40 years!

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