Could An ExtraTerrestrial Find Earth with a Telescope?

Active Seti writes "If aliens were hunting life outside their own planet, could they peer through the vastness of space and lock onto Earth as a likely home for life? Researchers say with a roughly Hubble-sized array observers could measure Earth's 24-hour rotation period, possibly leading to observations of oceans and the chance of life. 'They would only be able to see Earth as a single pixel, rather than resolving it to take a picture,' said Astronomer Eric Ford. 'But that could be enough for them to identify our planet as one that likely contains clouds and oceans of liquid water.' The research will be useful to astronomers designing the next generation of space telescopes on our planet, because it provides an outline of the capabilities required for studying the surfaces of Earth-like worlds."

Comments

Too many assumptions?

[RobertM1968]

The article makes a lot of assumptions such as:
(1) Life on other planets has the same requirements for existence as us (Class M
        planet, water, air like ours, gravity like ours, etc)
(2) Extra-terrestrials will be using technology similar to ours (as opposed to more advanced tech)
(3) (Basing off #1 being true as they did) there are planets suitable for life such as ours that
        we haven't yet discovered that are looking in our direction.

Do we want to be found?

[brassman]

"Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us."

Lightspeed is slow

[GeneralCC]

Well, if extraterrestrials were able to see earth using electromagnetic radiation (ie light, radio waves, ect) depending on their distance they would not see a modern earth. If they were over 5 billion light years away then if they looked at this solar system the Sun and the Earth would just be forming. This is because light speed is too slow. By the time the light reaches the extraterrestrials a large amount of time would have passed. They would have to use something other than a telescope to see a modern life sustaining Earth.

Re:I've got an idea

[RAMMS EIN]

``Sometimes I think the surest sign that intelligent life exists elsewhere in
the universe is that none of it has tried to contact us.''