Weekend SkyWatcher's Forecast: January 29-31, 2010 | Universe Today

Written by Tammy Plotner

Greetings, fellow SkyWatchers! The Full Moon and Mars… the Full Moon and Mars… Will they be as big as each other? Or dance with the stars? Be sure to take time out of your busy evening to at least step outside to check out this relatively close visual pairing. You might not need a telescope for the weekend conjunction, but be sure to bring one along as we check out some very special stars along the way! Now, let's wait on the Sun to set and I'll see you in the back yard….

Friday, January 29, 2010 – Although the internet will probably light up with a plethora of mis-information, the truth is that the full Moon and Mars are going to be putting on quite a show in the sky as they pair up for a conjunction. Mars is now at opposition – which means it rises directly opposite the Sun in the sky and is viewable all night. Coincidentally, so is the first Full Moon of 2010! Although positions will vary slightly depending on your viewing area and time, the show will begin as the pair rises side by side just after local sunset, appear overhead at local midnight and set to the west as the Sun rises again, never straying more than about 6 degrees apart. If your skies are cloudy tonight? Hey… Don't be upset. Just look again on Saturday when the Moon switches "sides"!

But the planetary alignment fun doesn't end there. Keep watching as the Moon tracks away from Mars and heads towards Saturn! It's a great lesson on how to see exactly where the ecliptic plane is in your local sky. By Tuesday, February 2, 2010 the waning wanderer will also make a very close pass at the ringed planet as it moves along the ecliptic in clockwork fashion. While you're there, be sure to turn a telescope towards 204 light year distant Eta Virginis, just south of Saturn. It's name is Zaniah, at it's positioned right on the ecliptic. Although it visually a appears to be a solitary star, lunar occultations have shown Eta to be a very close triple star system!

While we're observing the planet dance, be sure to remember William Ferrel who was born on this day in 1817.. His equations, known as ‘‘Ferrel’s Law,’’ demonstrated how Earth’s rotation affects high and low pressure systems, and the deflection of air and water currents. Ferrel also studied solar and lunar gravity and the effects created on Earth’s rotation. Even with no proof, he was first to claim Earth’s axis had a wobble!

Saturday, January 30, 2010 – Tonight, let’s observe the small star found just south of the easternmost ‘‘belt’’ star in Orion – Sigma (RA 05 38 44 Dec 02 36 00). Small optics close the 1,150 light-year gap and reveal this multiple-star system in all its red, white, and blue beauty. Fine optics at high magnification can resolve four members.

The brightest, A/B, is one of the most massive binaries known and ignites the surroundings in a glow of interstellar gas. The D and E members are nearly identical in magnitude, yet E is, oddly, a helium-rich star, likely related to Cor Caroli types. Nearest to the primary A/B pair is C—a totally normal dwarf. As part of a larger grouping, Sigma’s fate is unclear. The A/B union is solid, but the orbits of its companion stars are highly unstable. Chances are that when the A/B pair has evolved fully and is ready to end its life quietly as a pair of white dwarfs, it will eject the others. The larger Sigma Orionis grouping also contains many low-mass stars about three times larger than Jupiter, and many planetary candidates. It’s an interesting area of the sky, and well worth your time!

Sunday, January 31, 2010 – What a busy date in astronomy history! In 1958 the United States. launched its first satellite – Explorer 1 – which discovered the bands of radiation now referred to as the Van Allen Belts . In 1961 the Mercury-Redstone 2 launched, carrying Ham the chimpanzee to fame. Cabin pressure failed during the suborbital flight, but inside his pressure suit, Ham remained safe and performed his tasks with a reaction time only a half second slower than on the ground, proving primates could function in space! Ham lived for another 17 years, and the celebrated chimp gave many performances – even guest starring in movies! Luna 9 was launched in 1962 and 72 hours after its launch became the first craft to successfully touch down on the Moon and broadcast television from Oceanus Procellarum . Even Apollo 14 was Luna-bound today in 1971!

Alvan Graham Clark , Jr, made history at the eyepiece on this date in 1862. While watching Sirius and testing an 1800 refractor his -family built, Clark uncovered the intense star’s faint companion – Sirius B. Friedrich Bessel had proposed its existence back in 1844, but this was the first visual confirmation. Try your own hand at the ‘‘Scorching One.’’ Alpha Canis Majoris has an amazing magnitude of +1.42. Next to Alpha Centauri , 8.7 light-year distant Sirius is the closest visual star, but it’s not standing still. Part of the Ursa Major moving stream, Sirius has changed position by one and half times the apparent width of the Moon in just 2,000 years! Telescopically, this main-sequence gem is dazzling white, tinged with blue and diffracts a rainbow of colors. For many of us, beautiful iridescence is all we’ll ever see, but a 1000 telescope under perfectly steady skies will reveal the secretive companion. In less than 20 years it will reach maximum separation of 11.500, so keep watching to Sirius’ southeast when you observe – perhaps (thanks to Moon bright skies) you’ll spot B!

Unitl next week? Keep your feet on the ground and your eyes on the skies!

This week's awesome images are (in order of appearance): The Moon and Mars (courtesy of joka2000 – Wikipedia), Sky Maps by Your Sky, Wiliiam Ferrel (historical image), Orion from the Southern Hemisphere (courtesy of Shevill Mathers), Ham the Chimpanzee (courtesy of NASA) and Sirius (courtesy of John Chumack). We thank you so much!

Filed under: Astronomy, Observing