StarDate

Moon and Companions


Listen Later

The Moon passes through the bull tonight. The bull’s “eye” – the star Aldebaran – is off to the left of the Moon. The bull’s face and shoulder are even closer, represented by a pair of star clusters – the Hyades and the Pleiades.

For the most part, you can’t tell the distance to an astronomical object just by its appearance. Something that looks quite bright might be close, but it might also be far away and especially bright.

But you can tell something about the distances to the objects around the Moon tonight by their appearance.

The Pleiades looks like a tiny dipper close below the Moon. It contains hundreds of young stars, some of which are hot and bright. But the cluster’s small size is a good indication of its distance – almost 450 light-years.

The Hyades looks bigger. It forms a letter V that outlines the bull’s face. It looks a good bit more spread out than the Pleiades. But that’s largely because it’s only a third as distant.

Aldebaran stands at the top left point of the V. It outshines all the other points. In part, that’s because it’s less than half as far – just 65 light-years away.

So these prominent features really do tell us something about their distances.

One other bright light stands directly below the Moon in early evening, and it’s the brightest of all: Venus, the “evening star.” Right now, it’s closer to us than anything else except the Moon.

Script by Damond Benningfield

...more
View all episodesView all episodes
Download on the App Store

StarDateBy Billy Henry