• 2 months ago
Crisp, clear October nights are full of celestial showpieces. Find Pegasus, the flying horse of Greek myth, to pinpoint dense globular star clusters and galaxies, and keep watching for space-based views of M15, NGC 7331, and the Andromeda Galaxy.

Credit: NASA and the Office of Public Outreach (STScI) http://www.stsci.edu/
Transcript
00:00October. Tonight's Sky. Constellations.
00:13The crisp, clear nights of October are full of celestial showpieces for the
00:19backyard skygazer. Face southeast after dark to find Pegasus, the flying horse of
00:28Greek myth, soaring high into the sky. The prominent square of stars that forms
00:36the body makes Pegasus a good guidepost for the autumn sky. Along the western
00:43side of the great square of Pegasus lies the star 51 Pegasi. It is notable as the
00:52first Sun-like star discovered to harbor an orbiting planet. Farther west, near the
01:01star Enif, which marks the horse's nose, lies an entire city of stars, the globular
01:08star cluster M15. Backyard telescopes show a grainy, concentrated sphere of
01:17light. NASA's Hubble Space Telescope shows a stunning globe of ancient stars
01:27with many red giants. M15 is one of the densest globular star clusters known in
01:37the Milky Way galaxy. Near the great square resides an even larger star city,
01:45the galaxy NGC 7331. In a telescope, the nearly edge-on spiral galaxy appears as
01:57an elongated smudge of faint light. The Hubble view shows that NGC 7331 is a
02:09galaxy very similar in size and structure to our own. NASA's Spitzer Space Telescope's
02:17view of the galaxy, which highlights infrared light, reveals a ring of dust
02:23circling the galaxy's center at a radius of nearly 20,000 light-years. Spitzer
02:33measurements suggest that the ring contains enough gas to produce four
02:38billion stars like the Sun. The brightest star of the Pegasus Great Square, named
02:47Alpheratz, marks the head of the princess Andromeda. Beside the Andromeda
02:56constellation is M31, the Andromeda galaxy. Visible in dark skies as an
03:05elongated patch of light, the galaxy at 2.5 million light-years distant is the
03:12farthest object that can be seen with the unaided eye. Binoculars and small
03:20telescopes clearly show its nearly edge-on shape.
03:26NASA's GALAX mission imaged the ultraviolet light from the Andromeda
03:32galaxy. The image shows its core and spiral arms traced by hot, massive young
03:42blue stars and dark dust lanes. Andromeda is the nearest large galaxy to our own.
03:52Studies indicate that Andromeda is approaching and will collide and merge
03:58with the Milky Way more than four billion years from now.
04:05Enjoy the patterns of stars, star clusters, and galaxies on clear October
04:13nights. Celestial wonders await you in tonight's sky.