Transit of Venus – Party at HCC

The Meade Telescope Safely Projecting an Image of the Sun and Venus
Image Credit: Dave Fischer

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.

The Transit of Venus Projected on our Screen
Image Credit: Dave Fischer

Venus Transits the Sun – Observation on Tuesday Hosted by The Humanist Society of Greater Phoenix

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 2012 Transit by Venus as seen from the Mauna Loa Observatory, Hawaii
Image Credit: HSGP

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:

The safest way to watch a transit is to observe an image of the Sun projected onto a screen through a telescope, binoculars, pinhole[7] or reflected pinhole.[8] The event can be viewed without magnification using filters specifically designed for this purpose, such as an astronomical solar filter or eclipse viewing glasses coated with a vacuum-deposited layer of chromium. However, the disk of Venus is tiny compared to the sun and not much will be seen. The once-recommended method of using exposed black-and-white film as a filter is not now considered safe, as small imperfections or gaps in the film may permit harmful UV rays to pass through. Observing the Sun directly without appropriate protection can damage or destroy retinal cells, causing temporary or permanent blindness.[9][10][11]

The Humanist Community Center in Mesa
Image Credit: HSGP

More Planets than Stars – But Axial Tilt is the Key to Life

There is an average of more than one planet per star in the Milky Way
Image Credit: NASA / ESA / ESO

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.

Relative size of the three rocky planets around KOI-961
Image Credit: NASA / JPL-Caltech

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

Spitzer Infrared Image of Messier object M27
Image credit: NASA / JPL-Caltech / Harvard-Smithsonian CfA

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

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

  • Come see the winter sky! Take our Astronomy Quiz!
  • View exciting celestial objects through our telescopes!
  • Learn about rocks with the GEO Club!
  • Want to see a rock from Space? Stop by the meteorite table!
  • View our out-of-this-world poster display!
  • Have a question about the universe? Ask an Astronomer!
  • For information about the moon, stop by the LROC table!

Planetarium show: TBD

Talk: Stars in our Galaxy

Contact Information:

Star Comparison
Comparison of Star Size – Our Sun is the Smallest Dot and Antares is the Big Dude
Image Credit: ASU

Comet 103P / Hartley 2 – Rendezvous

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

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.

Hartley 2 816 km
Comet Hartley 2 from EPOXI at 816 km
Image credit: NASA / JPL-Caltech / UMD

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.

Hartley 2 700 km
Comet Hartley 2 at 700 km.
Image credit: NASA/JPL-Caltech/UMD

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.

Five Comets visited by Spacecraft
Image credit: NASA/JPL-Caltech/UMD

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

Lutetia from 60,000 km.

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.

Closing on Lutetia with Saturn above.

Leaving Lutetia – Night side.

Lutetia Closest Approach

Lutetia – Crater Close Up

Lutetia – GroovesClose Up

Let us know what you think. What do you want to know about? Post a comment.

Fifty Years of Space Exploration

Eye Candy from National Geographic.

50 Years
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

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:

  • L-1 is, as one might suspect, located between the two bodies, where the gravitational pull of each body equals the other. This point is unstable. That is, if a satellite deviates in any way from the point, it will fall into the gravity well of one or the other bodies. The Solar and Heliospheric Observatory (SOHO) is located at SEL-1 in a Halo Orbit.
  • L-2 is beyond the smaller body, where the combined gravitational pull of the two bodies balances the centrifugal force of the satellite. Satellites currently at SEL-2 include the Wilkinson Microwave Anisotropy Probe, the Planck space observatory and Herschel Space Observatory. L-2 is also an unstable point, and all three satellites occupy Lissajous orbits around the Lagrange point
  • L-3 lies beyond the larger body away from the smaller body. SEL-3 is on the other side of the Sun from the Earth.
  • L-4 lies at the corner of an equilateral triangle whose base is between the two bodies, ahead of the direction of the orbit of the smaller body. The Trojan asteroids occupy SJL-4 and SJL-5 of the Sun-Jupiter system. Both L-4 and L-5 are stable, as shown by the gravity contours in the diagram.
  • L-5 lies at the corner of an equilateral triangle whose base is between the two bodies, behind the direction of the orbit of the smaller body. EML-4 and EML-5 were popularized by G. K. Oneill as places to build human space colonies. This was the impetus for the founding of the L5 Society.

Wikipedia has an excellent article on Lagrange points in space.

Lagrange Points

Image from notes by Neil J. Cornish from the NASA WMAP Wilkinson Microwave Anisotropy Probe web site.