In September, Pegasus becomes increasingly prominent in the southeastern sky, allowing stargazers to locate globular star clusters and a nearby double star, Alpha Capricorni. Keep watching for space-based views of densely packed, spherical collections of ancient stars in visible and X-ray light.
Credit: NASA and the Office of Public Outreach (STScI) http://www.stsci.edu/
Credit: NASA and the Office of Public Outreach (STScI) http://www.stsci.edu/
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00:00September, Tonight's Sky, Constellations.
00:15As September brings transition from summer to fall,
00:19the sky transitions to the stars of autumn.
00:27Increasingly prominent in the southeastern sky
00:30is Pegasus, the winged horse.
00:36The great square of stars that outlines the body
00:39is a useful guide to the fall patterns around it.
00:48Near the great square lies the sprawling pattern
00:52of Aquarius, the water-bearer.
00:59Located within the western part of the constellation
01:02is M2, one of the oldest and largest globular star clusters
01:08associated with the Milky Way galaxy.
01:13It appears as a circular, grainy glow in backyard telescopes.
01:22NASA's Hubble Space Telescope has imaged the cluster,
01:26a compact globe of some 150,000 stars
01:32that are more than 37,000 light-years away.
01:39At approximately 13 billion years old,
01:43this cluster formed early in the history of the universe
01:46and offers scientists an opportunity
01:49to see how stars of different masses live and die.
01:57Results from ESA's Gaia satellite
02:00suggest that this cluster, along with several others,
02:04may have once belonged to a dwarf galaxy
02:07that merged with the Milky Way.
02:15West of Aquarius is the constellation of Capricornus,
02:19the sea goat,
02:20a figure dating back to the Sumerians and Babylonians.
02:27The star at the western end of Capricornus
02:30is Alpha Capricorni.
02:36Alpha Capricorni is an optical double,
02:39but not a binary pair.
02:42The brighter star, Algedi, is about 100 light-years away.
02:47The fainter lies along the same line of sight,
02:50but is roughly eight times farther away.
03:00The pattern hosts another globular star cluster, M30.
03:09It appears as a hazy glow in small telescopes.
03:18Stars are packed so closely in globular clusters
03:22that they can interact with each other.
03:24Binary stars can exchange partners
03:27in their tight gravitational square dance.
03:31More massive objects, like black holes and neutron stars,
03:36move toward the center.
03:40M30 likely started life with another galaxy
03:44that merged with our own.
03:47The globular cluster is orbiting the Milky Way
03:50in the opposite direction of most stars.
03:55Look west to find the constellation Sagittarius,
03:59the centaur archer in the sky.
04:04Past the centaur's arm,
04:06you will find another globular star cluster, Terzan V.
04:14Terzan V sits near the dark dust lanes of the Milky Way.
04:22Bright blue young stars are visible
04:25in the foreground of the ancient cluster.
04:32The core of Terzan V shines brightly with the X-ray light
04:36from white dwarfs and neutron stars.
04:45Take advantage of mild late summer nights
04:49to enjoy the constellations and ancient globular star clusters
04:53of the September sky.
04:57Celestial wonders await you in tonight's sky.