Every observation out into deep space is also a look back in time.
... [+]
overhead. The celestial objects we see in Earth's night sky are being viewed as they were when their light was emitted: seconds, hours, years, or even millions of years ago, depending on which object we're observing.When one of Jupiter's moons passes behind our Solar System's largest planet, it falls into theplanet's shadow, becoming dark.
159.6 minutes, or 2 hours and ~40 minutes, to reach Earth. Uranus, which has a prominent lunar system and its own rich set of rings, is the most distant naked-eye object in the Solar System.The two sun-like stars, Alpha Centauri A and B, are located just 4.37 light years away from us andorbit one another at between the distances of Saturn and Neptune in our own solar system. Even in this Hubble image, however, they are simply oversaturated point sources; no disk can be resolved.