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FRIENDS OF THE PLANETARIUM NEWSLETTER – NOVEMBER 2009
Welcome to our last newsletter of the year. Plans are afoot for improvements for 2010. We will be sending out the
newsletter quarterly, not just three times a year. The newsletters will coincide roughly with the Solstices and
Equinoxes so expect a newsletter around the end of March. Also, we are offering you the opportunity to receive
your newsletters by email. This helps out in two ways. First, the Planetarium saves on postage. Second, you get to
see the pictures that we include in their original colours, not just a black and white photocopy. If you would like to
receive your newsletter by email, contact us at the address above.
There have been a lot of exciting discoveries in the Solar System recently. NASA’s LCROSS mission has
confirmed that there is water (in the form of rock hard ice) on the Moon. "We are ecstatic," said Anthony
Colaprete, LCROSS project scientist and principal investigator at NASA's Ames Research Center. The LCROSS
spacecraft and a companion rocket stage made twin impacts in crater Cabeus near the Moon's south pole on Oct.
9th. A plume of debris traveled at a high angle beyond the rim of Cabeus and into sunlight, while an additional
curtain of debris was ejected more laterally. "Multiple lines of evidence show water was present in both the high
angle vapor plume and the ejecta curtain created by the LCROSS Centaur impact," says Colaprete. "The
concentration and distribution of water and other substances requires further analysis, but it is safe to say Cabeus
holds water." Since the impacts, the LCROSS science team has been analyzing the huge amount of data the
spacecraft collected. The team concentrated on data from the satellite's spectrometers, which provide the most
definitive information about the presence of water. A spectrometer helps identify the composition of materials by
examining light they emit or absorb. Team members pledged to announce other results as they gain confidence in
the ongoing analyses.
Further out the Saturnian system continues to amaze us. NASA's Spitzer Space Telescope has discovered an
enormous ring around Saturn, by far the largest of the giant planet's many rings. The new belt lies at the far reaches
of the Saturnian system, with an orbit tilted 27 degrees from the main ring plane. The bulk of its material starts
about six million kilometers away from the planet and extends outward roughly another 12 million kilometers. One
of Saturn's farthest moons, Phoebe, circles within the newfound ring, and is likely the source of its material.
Saturn's newest halo is thick too; its vertical height is about 20 times the diameter of the planet. It would take about
one billion Earths stacked together to fill the ring. The ring itself is tenuous, made up of a thin array of ice and dust
particles. . Its particles are diffuse and may even extend
beyond the bulk of the ring material all the way in to Saturn
and all the way out to interplanetary space. The discovery may
help solve an age-old riddle of one of Saturn's moons. Iapetus
has a strange appearance, one side is bright and the other is
really dark, in a pattern that resembles the yin-yang symbol.
The astronomer Giovanni Cassini first spotted the moon in
1671, and years later figured out it has a dark side, now named
Cassini Regio in his honour. Saturn’s newest addition could
explain how Cassini Regio came to be. The ring is circling in
the same direction as Phoebe, while Iapetus, the other rings
and most of Saturn's moons are all going the opposite way.
According to the scientists, some of the dark and dusty
material from the outer ring moves inward toward Iapetus,
Credit: NASA/JPL-Caltech/Keck
slamming the icy moon like bugs on a windshield.
Astronomers have long suspected that there is a connection between Saturn's outer moon Phoebe and the dark
material on Iapetus. This new ring provides convincing evidence of that relationship.
Still at Saturn, the Cassini spacecraft had its latest flyby of Saturn’s moon Enceladus on Nov.21. The Visible and
Infrared Mapping Spectrometer (VIMS) observed Enceladus as the moon emerged from eclipse, followed by a
Composite Infrared Spectrometer (CIRS) fast raster
scan of Enceladus' night side. The Imaging Science
Subsystem (ISS) then took over for high-resolution
plume observations obtaining a clear filter mosaic of
terrain on the leading hemisphere. These data and
images will be processed and analyzed in the coming
weeks. They will help scientists create the mostdetailed-yet mosaic image of the southern part of the
moon's Saturn-facing hemisphere and a contiguous
thermal map of one of the intriguing "tiger stripe"
features, with the highest resolution to date. Scientists
are particularly interested in the tiger stripes, which are
fissures in the south polar region, because they spew jets
of water vapor and other particles hundreds of
kilometers, or miles, from the surface. This flyby was
scientists' last peek at the tiger stripes before the south
pole fades into the darkness of winter for several years.
Image credit: NASA/JPL/Space Science Institute
At the outer edge of our Solar System, the mysteries continue. For years, researchers have known that the Solar
System is surrounded by a vast bubble of magnetism. Called the "heliosphere," it springs from the sun and extends
far beyond the orbit of Pluto, providing a first line of defense against cosmic rays and interstellar clouds that try to
enter our local space. Although the heliosphere is huge and literally fills the sky, it emits no light and no one has
actually seen it. Until now. NASA's IBEX (Interstellar Boundary Explorer) spacecraft has made the first all-sky
maps of the heliosphere and the results have taken researchers by surprise. The maps are bisected by a bright,
winding ribbon of unknown origin. Although the ribbon looks bright in the IBEX map, it does not glow in any
conventional sense. The ribbon is not a source of light, but rather a source of particles, energetic neutral atoms or
ENAs. IBEX's sensors can detect these particles, which are produced in the outer heliosphere where the solar wind
begins to slow down and mix with interstellar matter from outside the Solar System. The ribbon also has fine
structure, small filaments of ENA emission no more than a few degrees wide. The fine structure is as much of a
mystery as the ribbon itself, researchers say.
Beyond our Solar System, the search for exoplanets, planets orbiting other stars, continues apace. Astronomers
have found 32 new planets outside our Solar System with the High Accuracy Radial Velocity Planet Searcher,
better known as HARPS, the spectrograph for the European Southern Observatory's (ESO) 3.6-metre telescope.
The number of known exoplanets is now at 406, and HARPS itself has discovered more than 75 exoplanets in 30
different planetary systems. Included in this most recent batch are several low-mass planets, so-called "Super
Earths" about the size of Neptune. One such planet has been discovered that is 6 times the mass of Earth, which
circles the low-mass host star, Gliese 667 C, at a distance equal to only 1/20th of the Earth-Sun distance. Two
other planets were discovered previously around this star. ESA’s COROT space telescope has discovered one of
the more bizarre exoplanets to date. If any creature lives on COROT-7b, the recently confirmed rocky exoplanet,
they might think the sky is falling. This planet is close enough to its star that its "day-face" is hot enough to melt
rock, and according to models by scientists at Washington University, COROT-7b's atmosphere is made up of the
ingredients of rocks and when "a front moves in," pebbles condense out of the air and rain into lakes of molten lava
below. This is not a nice place.
Fortunately for us, our atmosphere protects us from falling rocks like the one that exploded over the town of Bone,
Indonesia on October 8th. The explosion was due to an asteroid about 5-10 meters in diameter exploding in the air
between 15 and 20 km above sea level. It was on the scale of 30 - 50 kilotons of TNT, more than twice as
powerful as the bombs used at the end of World War II. It triggered IMS detectors more than 10,000 km from the
blast!
Seasons greetings everyone and keep watching the sky.