You are here


August 28, 2011

Most of the constellations are tough to pick out. Their classical "connect-the-dots" outlines are so faint, small, or spread out that it's tough to see them as a picture.

That's not the case for two of the most prominent constellations of summer, though. Scorpius and Sagittarius are big and bright, and they're easy to pick out. Tonight, they're in the south as night falls. Look for the curving body of the scorpion just above the horizon, with the orange star Antares in its middle. Sagittarius is to the left of the scorpion, with its brightest stars forming a teapot.

If you have a dark sky, away from city lights, look about halfway between them -- between the scorpion's stinger and the teapot's spout -- for a hazy patch of light that's a bit bigger than the full Moon.

That's M7, a star cluster that's close to a thousand light-years away. Its 80 stars all formed from the same cloud of interstellar gas and dust, sometime between 200 million and 300 million years ago.

One reason the cluster stands out is that several of its stars are nearing the ends of their lives, so they've puffed up to giant proportions. Such stars are hundreds of times brighter than the Sun, so they're visible across great distances.

Binoculars will reveal quite a few more of the cluster's stars, while a small telescope will let you see most of them -- a family of stars nestled between two prominent constellations of summer.

More about Scorpius tomorrow.


Script by Damond Benningfield, Copyright 2011


Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.