Daily Space: Say hello to the neighbors

How far can you see? If you’re standing on the beach looking out to sea, the distance to the horizon is, surprisingly, only a bit over three miles. But of course, everyone has been to the top of a mountain, or even a building, where they could see across a city, or even into multiple states.

And that’s before you start looking up. The International Space Station makes a fairly spectacular “star” in the sky as it passes by around 250 miles overhead (with binoculars, you can make out the solar panels). On a clear night in a dark area, it takes only minutes to spot a GPS satellite scooting across the sky in orbits that average around 12,500 miles. The moon runs around 240,000 miles away. The visible planets go from Mars (average distance 96 million miles) to Neptune (average distance 2.7 billion miles).

Then you’re on to the stars. Promixa Centauri may be closest (4.25 light-years), but it’s both mostly out of view to the northern hemisphere and so dim it can’t be seen with the naked eye. There are far more distant stars that are far more easily spotted. Sirius, “just” 8.6 LY distant, is the second brightest star after the Sun. Canopus is next brightest, but it’s much farther away, 310 LY. It just happens to be a big bruiser, 71 times the width and 10,000 times the brightness of the Sun. Blue-white supergiant Deneb cracks the top 20 brightest stars even though it’s a whopping 2,615 LY away.

If you’re really observant, and you have a good area with low light pollution, you can spot an apparently dim star known as V762 Cas in the constellation Cassiopeia.  At 16,308 LY away, this faint dot is actually a massive red supergiant. There’s a decent chance that it’s already gone supernova. We just don’t know it yet.

But you’re not done. There are still things you can see out there that are a lot farther away.