What’s Up in the Sky – October, 2012

October Offers a Variety of Viewing Opportunities

This month’s sky has a lot to offer the interested observer. Nothing spectacular or historic is likely to occur, but there are number of opportunities to see some familiar friends getting together.
Some of the best planetary observing occurs before dawn. I always like watching things move from day to day and with Venus dominating the eastern early morning sky, you can easily watch the crescent Moon pass the planet on the mornings of October 11 – 13. Don’t miss Venus pass very close to the star Regulus on the morning of October 3.
Another interesting phenomenon to observe while you are out looking at the Moon and Venus is the Zodiacal light. For two weeks beginning Oct.13, it appears as a faint, pyramidal glow rising above the eastern horizon. The Zodiacal light is produced by sunlight reflecting off tiny dust particles in the plane of the solar system. You do need rather dark skies to see it, however.
If you crave a challenge, on the morning of the 14th, use binoculars and try to find the very thin crescent Moon very low in the east starting 45 minutes before sunrise.
The sky after sunset has its own share of visual treats. The Moon plays the passing game with Mars as well. Look for the thin crescent Moon a half hour after sunset on the nights of October 17 – 20. Mars will be to its upper left on the 17th and lower right on the 18th. Just below and to the left of Mars is the star Antares, which is very similar to Mars in both color and brightness. (In fact, the name “Antares” means “rival of Mars”). The two appear closest on the evening of the 20th. Kids – is Mars really as bright as Antares? Why does it look like it is?
The modest Orionid meteor shower occurs this month on the 20th – 22nd. The Orionids are characterized by very fast meteors that streak across the sky although at a relatively low rate of about 20 per hour. This time of year it is also possible to witness meteors from the Taurid shower. These can sometimes appear as dazzling fireballs, sometimes even visible in the daytime.
Early or late, October should be a good month to enjoy what’s up in the sky.

This month in history:
Oct. 1: 300-foot radio telescope at Green Bank, WV begins operations – 1962
Oct. 4: Space Age begins when Sputnik 1, first artificial satellite, is launched – 1957
Oct. 10: Dedication of VLA – Very Large Array radio telescope (as seen in the movie “Contact”) – 1980
Oct. 14: World’s first supersonic flight made by Chuck Yeager – 1947
Oct. 26: First flyby of Saturn’s moon Titan by Cassini spacecraft – 2004
Oct. 30: STS-61A Challenger Space Shuttle launched – 1985

September Offers Viewing Choices

If variety is the spice of life, then September’s dark skies might be described as the oregano of autumn. Lots of interesting, simple events will happen this month, and they will be easy to miss unless you know when and where to look. But then, that’s why you read this column so you’re all set.
August has its “Blue Moon” (the second Full Moon during the calendar month) this Friday, but September has the Harvest Moon, the Full Moon closest to the first day of autumn, so named because its light is useful for several consecutive nights during the harvest. This year that falls on September 29.
For reasons that stem from the geometry of the orbits of Earth and the Moon, in September, for several days before and after being Full, the Moon rises less than 30 minutes later each night. In March, by contrast, it is over an hour later. That means its light is useful to farmers harvesting their crops for a number of consecutive nights.
Another easy observation is to watch the Sun rise or set on the autumnal equinox (first day of autumn), which is on September 22 this year. The Sun rises due east and sets due west on that day. This is a great urban observation in an area with streets that run east-west, although it can be bothersome if you are driving into it. Watch for several days before and after the equinox and see if you notice any difference in the point on the horizon where it rises or sets.
For two weeks starting September 14 look for the Zodiacal Light one and a half to two hours before sunrise. Look for a broad, tall, rightward-leaning pyramid of light rising from the eastern horizon just below Venus.
Early risers will also enjoy Jupiter right above the Last Quarter Moon on the morning of Sept. 8 and Venus next to the Crescent Moon on the 12th.
On the 19th, look low in the SW 35 minutes after sunset for Mars just to the right of the Crescent Moon.

This month offers quite a variety up in the sky.

This month in history:
Sept. 3: Last two Apollo Moon landings canceled by NASA – 1970
Sept. 8: Voyager 1 launched – 1977
Sept. 18: Photo of Earth and Moon together in space taken by Voyager 1 – 1977
Sept. 21: Gustav Holst born – 1874
Sept. 23: Premier of “The Jetsons” – 1962
Sept. 26: Hyperion, a moon of Saturn, discovered by William Bond = 1848

Good Timing for Perseids

Everyone’s favorite summer meteor shower, the Perseids, has a good chance of fulfilling our expectations this year and its peak should occur at a convenient time.  This year the shower should be best on the Saturday night/Sunday morning of August 11/12.  With luck you may be able to observe one to two meteors per minute on average after midnight.  And that rate should increase as the night progresses until dawn.

Meteor showers occur when Earth collides with a swarm of particles left in the path of a comet that orbits the Sun.  It’s sort of like driving through a snowstorm or encountering a swarm of insects on a bike ride.

As the comet passes close to the Sun, solar radiation causes gases and solid particles to be released from the surface of the comet nucleus.  These particles follow the comet’s orbit and when Earth’s orbit intersects their path, we plow through the swarm and the particles burn up in our atmosphere.  More specifically, friction between the particle and the air ionizes the nitrogen and oxygen molecules that make up most of the atmosphere, causing the gases to glow and thereby leaving a visible trail which we observe.

The best way to observe a meteor shower is to find a site with a clear view of the horizon and away from the glow of city lights.  Set up a lawn chair, have a blanket or sleeping bag handy in case the night is chilly, bring some insect repellent just in case, and look up.  No special equipment is necessary – this is a naked eye observation.

August offers several other opportunities for interesting observations.  If you look low in the west-southwest an hour after sunset, you should see three relatively bright objects in a triangular formation.  These are Saturn on top, the star Spica on the bottom, and Mars in between.  Watch each night as Mars drifts toward the south, passing right between the others on August 13 and 14.  On the evening of the 21st, the trio is joined by a thin crescent Moon, a rare, beautiful gathering.

For you early risers, the planet Venus dominates the predawn sky.  Look for it just below the waning crescent Moon an hour before sunrise on the 13th.  Later that afternoon the Moon will pass in front of (occult) Venus.  This will be a chance for serious observers to witness a rare event, although a small telescope will be needed.  For more information see the August issue of Sky and Telescope magazine.

All in all, this should be a good month to enjoy what’s up in the sky.

This month in history:

August 5:                Neil Armstrong born – 1930

August 11:              Deimos, moon of Mars, discovered by Asaph Hall – 1877

August 1:                Saturn V production ends – 1968

August 18:              Cassini spacecraft flies by Earth – 1999

August 20:              First Redstone rocket launched – 1953

August 25:              Voyager 2 flies past Saturn – 1981

August 30:              NASA approves Lunar Orbiter program – 1963