International Year of Astronomy 2009

It was 400 years ago that Galileo Galilei first turned a telescope to the sky and began a program of careful observations that would challenge the powers that were, change the world, and give astronomy its most powerful tool of the last millennium. Below is a replica of his telescope (on display at the Griffith Observatory):

Around the world, people are celebrating this milestone in many ways. The worldwide webpage can be found here. The webpage for the United States is here. Finally, the Astronomical Society of the Pacific has created Discovery Guides for IYA2009 and they can be found here. Below is a table of the topics that will be discussed and the objects that will be featured for every month of this exciting year:

Month	Topics	Object
January	Telescopes and Space Probes	Venus
February	Our Solar System	The Moon
March	Observing at Night (and Day)	Saturn
April	Galaxies and the Cosmos	The Whirlpool Galaxy (M51)
May	Our Sun	The Sun
June	Star Clusters	The Hercules Cluster (M13)
July	Black Holes	Our Galaxy: The Milky Way
August	Rocks and Ice in our Solar System	Perseid Meteors
September	Planets and Moons	Jupiter
October	The Future of the Universe	The Andromeda Galaxy
November	Starlife	The Crab Nebula (M1)
December	Discovering New Worlds	The Orion Nebula (M42)

Here in the Sacramento area, several groups are working on things for the general public. The astronomy department here at Sacramento City College has monthly Open Observatories that will highlight the various objects that will be featured globally (except for the Sun). More information about the Open Observatory can be found here. In addition, near the SCC library viewings of the Sun with different tools will happen during many sunny Tuesday and Wednesday afternoons from January 28 through May 14.

How much do you know about astronomy? Here is a webpage detailing 44 common misconceptions about astronomy and explanations.

The Cameron Park Rotary Club Community Observatory (which is really in Placerville) is open most weekends throughout 2009 and is now working on several special projects for this special year. More about them and their programs can be found here.

The venerable Sacramento Valley Astronomical Society (SVAS) will be doing star parties at local schools and sidewalk astronomy at various urban locales so that the people can see their sky. The SVAS is our amateur astronomy organization and has been around for over sixty years! More information about them and their programs can be found here.

Since there are twelve months in a year and thirteen zodiac constellations, we will feature a new constellation each month with objects of interest for astronomers and astrophiles. Most people think there are only twelve zodiac constellations, but the Sun actually passes through (from our point of view) thirteen constellations. For more on this, go here.

For November we have a triple threat, as the Sun passes through three zodiacal constellations: Libra, Ophiuchus and Scorpius. Traditionally, Scorpius is the sun sign for late October and early November. The reason this doesn't add up is because of precession: all of the Sun signs are all off by one because the original system was setup over 2000 years ago and the sky has shifted since then. This does not explain why there are three zodiac constellations this month. Let's take a closer look: below is the sky on 10/31 which is when the Sun just enters Libra:

Again, Scorpius is a small constellation (or at least the part of it that the Sun passes through is). But the next one cannot be explained by either small constellations or precession. Here is the sky for 11/29:

If you've never heard of Ophiuchus, this isn't suprising. Yet you can clearly see above that the Sun passes through it. Why don't people call themselves Ophiuchans? Why aren't astrologers writing up things for people born in the sun-sign of Ophiuchus? So what should people do who are born between 11/29 and 12/17? I would suggest they check-out this website for more information: http://scc.losrios.edu/~sah/physics/44Miscon.htm#Astrology_and_Astronomy

Unfortunately, Libra is yet another faint (and therefore invisible to city dwellers) constellation. It also has some of the longest star names of all. Libra's brightest star is Zubeneschamali or Beta Librae. It has a magnitude of 2.6 which makes it hard to see in Sacramento. Since this is the brightest star, it's pretty much downhill from there.

Libra has one star that is very close to us (20 light years) - Gliese 581 - which has at least four planets orbiting it. The one discovered this year is the smallest exoplanet known with a mass about twice that of Earth. This planet orbits very close to its star. The other three planets are also small, with masses ranging from 17 times the mass of Earth to 5 times the mass of Earth.

HD 134987 is a star like the Sun about 80 light years from us and has at least one planet with at least 1.5 Jupiter masses.

HD 141937 is a Sun-like star that is about 110 light years from us and has at least one planet with at least 10 Jupiter masses.

Ophiuchus is a large constellation. The brightest star is called Rasalhague or Alpha Ophiuchi, a second magnitude star (2.1, or about as bright as the North Star). The next brightest star is Beta Ophiuchi with a magnitude of 2.8, which makes it visible here in Sacramento but it's still faint. Other notable stars are of the exploding kind. RS Ophiuchi, for example is a recurring nova which means that it explodes on a regular basis. It is believed it will one day turn into a Type Ia Supernova which involves the destruction of a white dwarf in a close binary star system.

Speaking of supernovas, we haven't seen any nearby ones for centuries. Someone who saw one was Johannes Kepler, who saw it near the star Theta Ophiuchi over four hundred years ago.

Also, one of the closest stars to the Sun is found in Ophiuchus - Barnard's Star. It is the second closest star system to the Sun after the Alpha Centauri system. Barnard's Star is famous for it's high speed against more distant background stars. It moves about 1° (which is equal to the width of two full moons) every 350 years. That doesn't sound fast, but consider that it's six light years away. It is moving very fast indeed. You can see this at: http://en.wikipedia.org/wiki/File:Barnard2005.gif

Since Ophiuchus is a large constellation, it has many things within it. No less than seven Messier objects are contained within. All of them are globular clusters and so are far away and in the Halo part of our Milky Way Galaxy. All of them are between Here's M9 (26,000 light years away):

Ophiuchus contains five known exoplanets, three of them discovered this year. HD 148427 is a star cooler than the Sun that is about 200 light years from us and has one known Jupiter massed planet orbiting it at a distance similar to Venus' distance from the Sun:

HD 149143 is a Sun-like star that is about 200 light years from us and has one known Jupiter massed planet orbiting it much closer than Mercury is to our Sun:

HD 149382 is a star that is about 240 light years from us and has one known planet which is at least fifteen times the mass of Jupiter (more or less a brown dwarf). The star is unusual is that it is very young and luminous, yet is less massive than the Sun. This is an odd situation:

HD 170469 is a Sun-like star that is about 200 light years from us. It's one known planet has a mass of 0.7 Jupiters and orbits its star at twice the distance of us from the Sun:

Finally a zodiacal constellation with bright stars and one of the brightest stars among them. Antares or Alpha Scorpii is the brightest. With a magnitude of 0.9, it's visible even to city dwellers. It is also one of the largest stars, in that if we replaced the Sun with Antares, we on Earth would be inside it. It's about 600 light years away. Scorpius is also one of the few constellations that look anything like what it claims to be: a scorpion. From the stinger star called Shaula to the claws west of Antares, the thing actually looks like a scorpion. Many of the stars in Scorpius are clearly visible and get more visible the further south you go. Many of these stars are very young, hot, and massive, part of the nearest stellar association, which is about 400 light years away.

Scorpius also has a fast nova, U Scorpii which only takes 10 years to go through a nova cycle.

Scorpius being in the Milky Way has many deep sky objects including four Messier objects. Two of them are open clusters and two of them are globular clusters. M6 is an open cluster about 1600 light years away:

M7 is an open cluster about 800 light years away (it's toward the center of the picture):

Scorpius has six known exoplanets, one of them being discovered this year. HD 145377 is a Sun-like star located about 190 light years from us. Its planet has a mass of at least 5.5 Jupiters and orbit its star about as far as Mercury orbits our Sun.

HD 153950 is an F-star (hotter than the Sun), that is about 160 light years from the Sun. Its known planet has a mass of at least 2.5 Jupiters and orbits between Venus' and Mars' distances from our Sun:

MOA-2008-BLG-310-L is a Sun-like star located 19,500 light years away from us. Its known planet has a mass of only 1/5 that of Jupiter and since it was found using gravitational lensing, the planet's distance from its star is unknown.