[Physicist]

One way to image objects clear across the galaxy would be with an x-ray interferometer such as MAXIM. From their website:

X-ray interferometry has the potential to resolve the event horizon of a supermassive black hole in the nucleus of a nearby galaxy and at the center of our galaxy. This is equivalent to

• resolving a feature the size of a dinner plate on the surface of the sun,
• observing a 100 km emission knot on the surface of Alpha Centauri,
• imaging the disk of a star in the Magellanic CLouds,
• mapping in detail the accretion disk at the center of the Milky Way,
• directly measuring the parallax of a star in the Virgo Cluster of galaxies, or
• resolving one-tenth of a light year at the far extent of the visible Universe.

[biblewonk]

Does the earth emit X-rays?

I remember reading about a nifty deep space probe that would travel 25-50 billion miles from earth. They were going to use a 1 meter parabolic mirror with a laser at the focus to communicate with the earth. I wonder what the numbers regarding wattage per distance at a given data rate show. I wonder how much better this is than radio frequency.