The Sky This Week, 2009 January 23 – 30

An Eastern Hemisphere eclipse, then the Moon catches Venus…

Orion Rising over Savage Farm, near Bluemont, VA Imaged with a Canon PowerShot A70 digital camera, 10s @ f/3.5, ISO 200, by Geoff Chester

This post is courtesy of The United States Naval Observatory

The Moon wanders back into the evening sky by the week’s end. New Moon occurs on the 26th at 2:55 am Eastern Standard Time. At this time, anyone who happens to find themselves awash in the vastness of the southern and eastern Indian Ocean will experience the first eclipse of the year. This will be an annular solar eclipse, one in which the Moon doesn’t completely obscure the Sun along the central path. This is a result of the Moon being close to its apogee (farthest from the Earth) and the earth being close to its perihelion (closest to the Sun). Most of the eclipse will occur over open water, except for portions of Sumatra and Borneo, where residents will see the fiery ring if the eclipse in the late afternoon.

Look for Luna’s slender crescent shortly after sunset (I saw it tonight at about 6:30pm Mr. G), low on the western horizon, on the evening of the 27th. Two nights later she finds her way to the company of Venus, appearing below the dazzling planet on the 29th and above her on the 30th.

This week is a good one to get acquainted with the constellation Orion (click here for information about Orion). This group of bright stars is probably the most distinctive in the entire sky, and with the possible exception of the Pleiades there’s probably more sky lore associated with Orion than any other constellation.

An interesting exercise for the beginning skywatcher is to simply count the number of stars that you can see within the trapezoidal outline of his four brightest stars. There will be a world-wide campaign this spring to make just such an observation. Known as “GLOBE at Night”, the objective is to use the number of Orion’s visible stars to characterize the brightness of the sky at different locations. The more stars you see, the darker your sky is. Virtually everyone can see his three bright “Belt” stars, but it takes some effort in urban skies to see more. However, it’s worth the effort, especially if you have binoculars or a small telescope.

A small group of three stars seems to hang from the left side of the “Belt”, and if you use the slightest optical aid on the middle member of these three “Sword” stars you’ll instantly see that something is different. This star seems to be surrounded by a faint glowing haze that takes on increasing complexity as you increase the size of your optics. The Great Nebula is actually a small part of an enormous cloud of interstellar gas and dust, a veritable stellar nursery, where infant stars are awaiting the final stages of their birth to visibility. There’s enough “stuff” out there to make over 10,000 stars like the Sun, and that’s just in the part we can see. Observers in truly dark sites can see a huge, faint nebulosity surrounding the entire constellation!

Bright Venus gets a visit from the waxing crescent Moon as the week ends. The dazzling planet is now a few weeks past her greatest elongation, and anyone with a small telescope can see that she now sports a fat crescent phase.

Baleful Saturn now rises at around 9:00 pm and is high enough to be easily seen in the east by 11:00. The ringed planet sports a soft amber glow in contrast to the icy-blue glint of Regulus, the bright heart of Leo, the Lion. The planet’s famous rings are just barely tipped toward our line of sight, and over the next several weeks they will very gradually open by a degree or two. Later this year the earth will cross the ring plane and they will effectively disappear in an event that happens once every 15 years.

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Honors Study Guide Q&A

Honors students, you will be taking your first semester exam next week Monday & Tuseday. This exam will be 20% of the first semester grade. I want you all to do your very best!

This week we are reviewing the study guide in class. You should have already completed the guide to the best of your ability so class time can be utilized to clarify points and cover certain topics we have missed.

What else can you do?

  • Use the online textbook user id: LMS123  password: lakeview
    Review chapters 6, 8, 9, 10, 14, 15, 16, and 22. At the end of each chapter is a study guide of key concepts and questions. In particular everyone should read chapter 22.
  • Review first marking period test and second marking period test (don’t worry about questions on stars).
  • Use the comments to this post to ask and answer questions.
  • Here are some astronomy documents to study:  seasons, planets, lunar phases.
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