[benm (OP)]

Joy has an astronomical question:

With the technology that we currently have, would we be able to detect ourselves if we were on a planet a thousand light years away???

Does anyone have any insight?

[Halc]

With the technology that we currently have, would we be able to detect ourselves if we were on a planet a thousand light years away?

With current technology, we cannot even see a planet that far away.  Current planet detection techniques mostly involve observing the host star moving from side to side as the planet tugs at it, or if you're quite lucky, as a periodic dimming of the star as the planet eclipses it.
Our current technology would not allow us to see ourselves (a person) if we're as close as the nearest planet, let alone 1000 light years away.  That's why all the good pictures of distant planets are taken by probes we've sent out there.

Concerning the title:  We can see quite far if the object is bright enough.  The current record holder is some quasar that is currently 22 billion light years away and well beyond the event horizon.  The only reason we can see it is because it was closer way back when the light that we're seeing now first left it.  Quasars are super bright things that put supernovas to shame.

[alancalverd]

The biggest signal we can make is to explode a 10MT hydrogen bomb. From a distance, this would be indistinguishable from about 100 large thunderstorms that occur every day, so to produce a signal indicative of "intelligent" life you would have to explode several at regular intervals, on the side of the earth facing your intended audience, and hope that someone is looking in your direction at the right time and for long enough to spot the pattern, in 1000 years' time.

Why you or they would want to do it is beyond my imagination.

[Janus]

To put things in perspective, consider the Hubble space telescope that gave us such great pictures of distant objects. It had a resolution of .05 arc sec ( an arc sec is 1/3600 of a degree).  This tells us how large an angular size something would have to have before the Hubble could distinguish as a single object.  For example if you had two objects, one black and one white next to each other, the pair together would have to have a angular size of at least 0.1 arc sec for the Hubble to see produce an image of them as a black pixel next to a white pixel,  If they were smaller, it would just make 1 gray pixel for both objects.

The Moon, for example as seen from the Earth has a an angular size of ~ 1/2 degree or 1800 arc sec. This means that if we could have pointed the Hubble at it (We couldn't, its sensors weren't designed to look at something that bright), it could distinguish objects as small as 1/36000 the diameter of the Moon.  The diameter of the Moon is ~ 3470 km, which means the smallest object the Hubble could have distinguished on the Moon would have to have been ~96 meters, across. 

We could also work out how far away the Earth would be to fill up even a single pixel.  Again, we'll start with the Moon. It would be 36000 pixels wide as seen from the Earth.  The Earth has 3 2/3 the diameter, so it would be ~132340 pixels across at the same distance. Angular size is inversely proportional to distance, so the Earth could only be 132340 times further than the Moon to show up as a full pixel.  This works out out be ~ 340 times the distance from the Earth to the Sun, or 1/186 of a light year.