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Tonight

Star of the week: Alpha Cephei is a rapidly rotating star

Astornomers used the CHARA array to learn the inclination, polar and equatorial radius and temperature, as well as the fractional rotation speed of Alpha Cephei.  Read about this work here.

Astronomers used the CHARA array at Georgia State University – optical interferometer – to learn the inclination, polar and equatorial radius and temperature, as well as the rotation speed of Alpha Cephei. Read about this work here.

The constellation Cepheus the King is not terribly conspicuous and can boast of only one relatively star. That star is Alderamin – aka Alpha Cephei – which is by far the brightest star in Cepheus, lighting up one corner of an otherwise faint house-shaped pattern of stars. While not one of the most conspicuous stars in the night sky, this star is easy to spot, and it is interesting for its rapid rotation on its axis. Follow the links inside to learn more about Alderamin, aka Alpha Cephei.

Orion the Hunter well up before dawn in September

Orion is noticeable for his three medium-bright Belt stars.  Look for this short, straight row of three stars high in the east before dawn.

Orion is noticeable for his three medium-bright Belt stars. Look for this short, straight row of three stars high in the east before dawn.

Orion the Hunter is always behind the sun as seen from Earth in June. It comes back to the predawn sky every year in late July. By early September, Orion is rising in the wee hours and is well up in the southeast an hour before dawn, as shown on today’s chart. Orion will soon be up by midnight, then 10 p.m. … and by December you’ll find it rising in early evening.

September 2014 guide to the five visible planets

Skywatcher, by Predrag Agatonovic.

Skywatcher, by Predrag Agatonovic.

Mars and Saturn appear at nightfall. Watch for them near the moon on August 31 and September 1. From southerly latitudes, you can also view Mercury near the sunset horizon. The morning planets are Jupiter and Venus.

Waxing moon moves past Mars and Saturn, nears star Antares

2014-sept-1-antares-mars-moon-saturn-night-sky-chart

The wide waxing crescent moon has moved eastward of the planets Mars and Saturn on the sky’s dome, and is now heading for Antares, the brightest star in the constellation Scorpius the Scorpion. The name Antares is Greek for “like Ares,” probably because the color of this star resembles that of its namesake planet, the Greek Ares or the Roman Mars.

Spectacular moon, Mars and Saturn at nightfall August 31

GregDiesel Landscape Photography wrote,

Last night’s view of the planets and moon, from GregDiesel Landscape Photography.

You won’t want to miss the beautiful celestial attraction on the evening of August 31, as the rather wide waxing crescent moon, and the planets Mars and Saturn all bunch up together in the southwest sky as darkness falls. Take a stroll with a loved one, or family and friends, to see all these worlds lighting up starry heavens first thing at nightfall.

Moon east of Spica, west of 2 planets at nightfall August 30

Moon moving toward Mars and Saturn on August 30, joins up with Mars and Saturn on August 31 and moves on toward Antares on September 1

Moon moving toward Mars and Saturn on August 30, joins up with Mars and Saturn on August 31 and moves on toward Antares on September 1.

As darkness falls around the world on August 30, look for the star Spica to the west of tonight’s waxing crescent moon. Planets Mars and Saturn are to the east of tonight’s moon. Remember, west is in the direction of sunset.

How far is a light-year?

The Orion Nebula, 1,500 light years from Earth. Image credit: NASA/JPL-Caltech/STScI

The Orion Nebula, 1,500 light years from Earth. Image credit: NASA/JPL-Caltech/STScI


Here’s your FAQ for this Friday ….

Light is the fastest-moving stuff in the universe. It travels at an incredible 300,000 kilometers (186,000 miles) per second. That’s very fast. A light-year is the distance light travels in one year. How far is that?

Moon near star Spica, heading for Mars and Saturn, on August 29

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As soon as darkness falls on August 29, look low in the southwest sky for the slender waxing crescent moon and the star Spica. Over the next few days, at nightfall, watch for the moon to move away from Spica and toward the planets Mars and Saturn. Be sure to catch the moon and Spica as soon as darkness falls, for the two will follow the sun beneath the horizon shortly thereafter.

Star of the week: 61 Cygni is the Flying Star

The orbital motion of component B relative to component A as seem from Earth as well as the true appearance from face-on view. The time steps are approximately 10 years.  Illustration via Wikimedia Commons

The orbital motion of component B relative to component A as seem from Earth as well as the true appearance from face-on view. The time steps are approximately 10 years. Illustration via Wikimedia Commons

This star, 61 Cygni isn’t among the brightest stars. In fact, it takes some effort just to find it, because it is not much brighter than the faintest stars visible to the unaided human eye. It is, however, among the most important of stars visible without optical aid. It has one of the largest proper motions – that is, sideways motions along our line of sight – of any star in our sky. Its large proper motion has given 61 Cygni the nickname Flying Star. Follow the links inside to learn more.

Moon and star Spica low in west after sunset August 28

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Look westward as soon as darkness falls on August 28 to catch the slender waxing crescent moon fairly close the horizon. That bright star close to the moon is Spica, the brightest in the constellation Virgo the Maiden. Don’t delay, though, when looking of the moon and Spica, especially if you live at northerly latitudes, for the twosome will follow the sun beneath the horizon by early evening.