Because the Sun is a spinning ball of gas, it’s wider through its equator than through the poles. The difference is so small that you really can’t see it. But for the brightest star of Eridanus, the river, it’s a different story.

Achernar is a binary – two stars held together by their gravity. They orbit each other once every seven years.

The system’s main star, Achernar A, is much bigger and heavier than the Sun, and thousands of times brighter. And it spins like crazy – its equator rotates at more than half-a-million miles per hour. That’s about 150 times faster than the Sun. As a result, the star is about 40 percent wider at its equator than at the poles. So instead of a ball, it looks like a fat M&M.

That high-speed rotation has a couple of interesting consequences. For one thing, because Achernar’s poles are much closer to its core – the source of the star’s energy – the poles are thousands of degrees hotter than the equator. That heat creates “winds” of gas from the poles. And the fast rotation flings material from the equator. That surrounds the star with a cloud of gas and dust – a veil around a whirling star.

Achernar is the southern tip of Eridanus. The star’s name means “river’s end.” It’s not visible from north of about Dallas. The rest of Eridanus is in better view. It begins next to the foot of Orion, which is in the east-southeast at nightfall, then curls to the right and down to the horizon.

Script by Damond Benningfield