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The Humanist Society of Greater Phoenix (HSGP) held a party to celebrate the Transit of Venus across the disc of the Sun. I won’t happen again for another 105 years. The Humanist Community Center is located at 627 W Eighth Street, Mesa Arizona. Below is the black disk of Venus crossing the Sun.
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Tag Archives: Sun
Venus Transits the Sun – Observation on Tuesday Hosted by The Humanist Society of Greater Phoenix
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The Humanist Society of Greater Phoenix (HSGP) is hosting an astronomy event Tuesday afternoon, 5 June 2012, featuring the Transit of the Sun by Venus. The location is the Humanist Community Center (HCC) located at 627 W. 8th Street Mesa, AZ. A map of the location is here.
The transit as seen in Phoenix begins a little after 3:00 PM, so arrive early at HCC. The hosts will have a variety of observation methods. Safety is a primary concern. Please note these warnings from Wikipedia:
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More Planets than Stars – But Axial Tilt is the Key to Life
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With the forthcoming publication in the journal Nature on 12 January, it is estimated that there are more than 100 billion planets in our Milky Way galaxy. That means more than one planet per star, and results show that there are more rocky small Earth-like planets than giant Jupiter-size gas planets. Most recent discoveries have come from the Kepler Observatory using transit observations. Some of the earliest confirmation of gas giants came from radial velocity Doppler observations. The conclusions in the Nature article are based on micro-lensing studies. Recent results from the Kepler Observatory have shown the existence of three small, rocky planets around the star KOI-961, a red dwarf. These three planets, named KOI-961.01, KOI-961.02 and KOI-961.03, are 0.78, 0.73 and 0.57 times the radius of Earth. The smallest is about the size of Mars (see below). Follow-up observations were made by the Palomar Observatory, near San Diego, and the Keck Observatory atop Mauna Kea in Hawaii.
Since it is now clear that rocky planets exist around millions, if not billions, of stars, the question arises as to whether there is life on them, and whether it may resemble life on Earth. Whether a planet exists in the “Goldilocks” region around a star depends on many factors. Three factors include the type of star, how far away from the star the planet resides and the atmospheric pressure of the planet. A red dwarf, such as Gliese 581, means the planet has to be closer than the Earth to our Sun. A white hot star means the planet has to be farther away. And if the atmosphere is low, like Mars, or to high, like Venus, liquid water is not likely. A fourth factor is axial tilt. If a planet has no axial tilt (the spin axis is perpendicular to the plane of its orbit around the star) then the polar regions freeze and the equatorial regions bake. There is little exchange between these regions due to atmospheric circulation. Axial tilt, such as the Earth has, allows distribution of heat between the equator and the poles. Even if a planet has axial tilt, a recent study shows that interaction at a close distance (within the “Goldilocks” region) with red dwarf will eliminate axial tilt in less than 100 million years. Bacteria on Earth required 1,000 million years to evolve. Theoretically, a planet with no axial tilt could possess bands between the equator and the poles where liquid water would exist. But, it is quite possible the atmosphere would collapse, with gases being driven off into space at the very hot equator, and freezing solid on the ground at the poles. Such a possibility faces the planets around KOI 961. Systems with stars like our Sun present better possibilities. The “Goldilocks” conditions exist much farther out, and axial tilt is eliminated much more slowly, as our Earth is witness. Systems such as Kepler-22b are good candidates. The conclusion drawn from these studies is that systems similar to our Solar System present the best opportunities for life. |
Spitzer Images Messier 27 in the Infrared
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NASA has released this new image of the “Dumbbell nebula,” also known as Messier 27. The image was taken in the Infrared by the Spitzer Space Telescope. The object was discovered in 1764 by Charles Messier. It was the 27th object he named in his catalog of nebulous objects. The Dumbbell nebula is located in the constellation Vulpecula, which is about 1,360light years away from Earth. The gaseous debris from the dying star is spread across 4.5 light years of space. The white dwarf at the center of the nebula was a sun-like star. After a lifetime of 9-10 billion years, it bloats and expels much of its material, now containing carbon, nitrogen, oxygen, silicon and other heavy elements, into interstellar space. These elements are recycled in the next generation of stars and planets. The diffuse green glow, which is brightest near the center, is probably from hot gas atoms being heated by the ultraviolet light from the central white dwarf. |
Arizona State University Astronomy Open House
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Arizona State University Astronomy Open House Friday, March 25, 8-10 pm Location: Bateman Physical Sciences Building H-wing Main Entrance (click here for a map of ASU showing the H- wing) Free Parking (after 7pm): Tyler Street Parking Garage; From parking garage go West along University Dr sidewalk (toward campus) until you see signs leading you to the entrance. (click here for a map of ASU showing the location) This Month’s Theme: STARS
Planetarium show: TBD Talk: Stars in our Galaxy Contact Information: astopenhouse@gmail.com |
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International Space Station Solar Transit During Solstice Eclipse
The International Space Station Transits the Sun during December’s Solstice Eclipse.
Image Credit: Thierry Legault
Comet 103P / Hartley 2 – Rendezvous
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The Jet Propulsion Laboratory at the California Institute of Technology has released this video of Comet Hartley. The images were taken by the EPOXI spacecraft at one hour intervals from 28 October to 3 November 2010 during the approach. The rotation of the comet nucleus is clearly shown and the gases are being spewed most actively from one end. Video Credit: NASA Jet Propulsion Laboratory California Institute of Technology |
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This image was taken during the approach at 7:59 AM Phoenix time (13:59 UTC) on 4 November. The Sun is to the right.
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The nucleus of Hartley 2 is about 2 km long and 0.4 km wide at the most narrow section. Active jets are clearly visible.
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Below is a montage of the five comets visited by spacecraft and photographed up close. Hartley 2 at 1.25 miles in length is by far the smallest of the five comets, but has the most intense activity in relation to its surface area.
Comet 9P Tempel 1 (4.7 miles), was impacted on 4 July 2005 by NASA’s Deep Impact mission, later re-purposed for the Hartley 2 rendezvous. Comet 19P Borrelly (5.4 miles) was photographed in 2001 by the spacecraft Deep Space 1. Comet 81P Wild 2 (3.4 miles) was visited by the Stardust mission in 1999. The mission returned samples of the comet’s tail. Comet Halley (9.3 miles) was visited in 1986 by the Giotto mission and the Vega program. |
Images of Lutetia
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The Rosetta spacecraft has now completed its fly-by of 21/Lutetia, discovered in 1852 by Hermann Goldschmidt from his Paris balcony. Lutetia was his first discovery, and the 21st confirmed asteroid. Goldschmidt would ultimately discover 13 more asteroids (Nos. 32,36,40,41,44,45,48,49,52,54,56,61 and 70). Following the fly-by of Lutetia, Rosetta is headed for comet 67P/Churyumov-Gerasimenko (C-G) in 2014. Rosetta will spend two years circling the comet and observing its behavior as C-G plunges from 500 million miles from the Sun to 120 million miles at perihelion,and then back out towards the orbit of Jupiter. While orbiting C-G, Rosetta will release Philae, designed to land on the comet. Below are the latest release of images from the Rosetta OSIRIS camera of the Asteroid Lutetia. Note the planet Saturn with its rings, sitting above the asteroid in the first image below, left. See previous posts on Lutetia and Rosetta: Rosetta Encounters Lutetia and Rosetta. |
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Fifty Years of Space Exploration
Eye Candy from National Geographic.
50 Years of Space Exploration
Image Credit: National Geographic
Click on the link for an expanded image. Click on the expanded image for a BIG expanded image.
Lagrange Point
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In the vicinity of two bodies in space that orbit each other lie five Lagrange points, named after Joseph-Louis Lagrange, the French / Italian mathematician (1736-1813). Lagrange made major contributions to various branches of mathematics, and discovered the Lagrange points in 1772 while working on the three body problem, first described by Sir Isaac Newton in 1687. The diagram at the left shows the location of the five points. The Earth-Moon system has five Lagrange points, commonly labeled EML-n, and the Sun-Earth system has five points, labeled SEL-n:
Wikipedia has an excellent article on Lagrange points in space. |
Image from notes by Neil J. Cornish from the NASA WMAP Wilkinson Microwave Anisotropy Probe web site. |
