With today's most powerful telescope, what is the smallest object we'd be able to see if it was on the moon?

Question

If we built a football field on the surface of the moon, would we be able to see it from Earth using the world's most powerful telescope? Could we see a man standing on the moon using the Hubble telescope?

Answer 1

The world's most powerful telescope is the Keck telescope in Hawaii. There are now two of them and they can be used in tandem to increase the resolution, which is a measure of the smallest thing you can see.

The resolution of the combined Keck pair is 5 milliarcseconds, which is equal to or greater than Hubble.
http://spie.org/x8797.xml?highlight=x2418

The moon at perigee (closest approach) is 363,104 km away.
http://en.wikipedia.org/wiki/Moon

An angle of 5 milliarcseconds, projected to a distance of 363,104 km would be 8.8 meters (29 feet) across, which is the smallest object we could see on the Moon from Earth under ideal conditions. The Apollo LEM lunar lander is about 20 feet across, and could not be seen.

Answer 2

The Hubble telescope could see a football field on the Moon, just barely, but not a man. But Hubble is not the largest telescope in the world, it is just the largest one in orbit. There are larger ones on the ground that could see smaller things, like maybe a tennis court, but still not a man, but in reality they cannot because of the blurring effects of the Earth's atmosphere. These blurring effects are the same ones that make the stars twinkle. But even if these giant telescopes were above the atmosphere like Hubble is, they are still too small to see a person on the Moon. Or a flag.

Answer 3

The Hubble Space Telescope's resolving power is similar to that used by the KH-11 photoreconnaissance satellites. With those optics, you can see objects about one foot wide from a distance of 300 miles.

From Hubble's low earth orbit to the moon, the distance is a bit more than 200,000 miles. At that distance, the smallest objects on the moon the Hubble Space Telescope's optics are capable of distinguishing would be a few hundred feet wide, i.e. a football field.

No, you cannot see things smaller than that on the moon using Hubble, and that includes moon buggies, flags or astronauts.

Answer 4

The reason an astronaut is simply to small to be seen (even with hubble). It would be like trying to read a book that was 30 miles away with some binoculars! It can be shown that it can't be seen with a little maths:

Let's say the largest object on the moon was 5 metres in diameter, I picked 5 because it's a nice round number! The distance to the moon is roughly 384,000 kilometres.

Angular Size = 5 / 384,000,000 = 13 billionths of a Radian

To convert from from Radians to degrees:

In degrees = (1.3 x 10-8) x 180 / Pi = 750 billionths of a degree across

Ok, so we've obtained in degrees the area that we would have to look at to be able to see that particular object, now I will tie this into hubble.

Astronomers use 'arcseconds' instead of degrees. There are 3600 arc seconds in a degree. If we do the maths 750 billionths of a degree x 3600 we get around 0.0026 arc seconds, but because we approximated with the distance I'll round this upto 0.003 arcseconds.

So, I hear you ask? What can hubble see? Our eye can see 60 arcseconds, The best telescope on the ground can see objects 0.5 arcseconds in size, hubble can see more clearly, upto 0.05 arcseconds in size. That makes the moon landing equipment 18 times smaller than what hubble can see. Even if it was 18 times bigger it would resolve to one pixel, to put that in perspective you probably have about 800 thousand pixels on your monitor right now!

Now then, that isn't the only problem! The moon is moving across the sky at 0.5 arcseconds due to it's orbit around earth, you can probably see the problem all ready! It would be like trying to take a sharp picture of a train whizzing by!

I hope this answers your questions,

Gav

Answer 5

WE could not see a man, everyone else is correct about maybe seeing a football field. You may wander what is WOULD take to see a man on the Moon.

Firstly, we would need an orbiter. And a very high resolution camera, such as a spy satellite.

If we were to put one of them around the moon, we could see humans, I personally think we should take pictures of the Apollo landing sites with a similar orbiter to end the stupid 'Moon landing hoax' once and for all.

Encase it interests you, I have found a Mars orbiter image, that can take images of the little rovers on the surface of mars. These are not really any bigger that a human who has spread them selves out, and they are amazing pictures.

http://www.nasa.gov/mission_pages/MRO/multimedia/mro-2061006-1.html

Thanks

Answer 6

Yes, you could see a football field, however, there is one thing you have to remember when viewing the moon. The moon moves very fast as viewd from the earth's surface, so viewing the surface of the moon under very high magnification is difficult. . .

Answer 7

giz - you may desire to comprehend that the criterion of value isn't magnification, yet selection shrink. there are multiple articles on line that describe this, yet suffice it to declare that it may desire to be possible to verify those gadgets if we experienced quite a few large scopes on the article in question and dealt with the array as a single telescope. by potential of combining each and all the photos taken concurrently over a large "aperture" created by potential of the array, you may purely fairly be waiting to verify something - even if it particularly is not a solid application for such an array, and the atmospheric disturbances could nonetheless maximum probable ward off it. Convincing an significant form of astronomers to take area in such nonsense (while they already have a scope that could come across laser alerts bounced back from the reflectors placed there by potential of Apollo 15 astronauts) could be completely unsuccessful. Why could desire to they waste their time in this while: a million. they have their own artwork that demands each loose 2d of available scope time. 2. it may require the form of such an array that could desire to be committed to this one attempt. the only way it could have a genuine looking probability of working could be to do it in earth orbit. The price could be prohibitive. it may probable be greater low-fee to return to the Moon and take a image. 3. even if in the event that they did see something, the fruitcakes could easily say it is not sparkling sufficient and does not have confidence it and could call for much greater of the scientists' valuable time to handle their stupid conspiracy notions. you spot, the conspiracy proponents won't be able to locate the money for to admit that they are incorrect. it may dry up their income source. So, no count what info is trotted out (and there are piles of it) they are going to consistently locate a thank you to cajole misinformed, ignorant human beings that the missions on no account got here approximately (or for that count, that there are UFOs approximately to land, the earth will cave in in 2012, or there's a planet named Nibiru). What a waste of time and suggestions synapses!

Answer 8

Hmm.

I'm not sure exactly how powerful the hubble is, but I'd say we could see a football field probably.

Answer 9

A football field -- yes, but nothing much smaller than that.

Definitely not the bottom portion of the Lunar Excursion Module (LEM), or a single man, or the flags.

Answer 10

We'd see a dot that was a football field. But pretty much nothing smaller. Every dot we saw would be the size of a football field.