Date: September 28th, 2012

Title: Monthly News Roundup – A Rocky Month

Podcaster: Morgan Rehnberg

Links:
Jupiter impact:
http://news.nationalgeographic.com/news/2012/09/120911-jupiter-amateur-astronomy-science-peterson-hall/
http://www.universetoday.com/97481/what-caused-the-recent-explosion-at-jupiter/
Earth’s ice age:
http://www.universetoday.com/97455/did-a-killer-asteroid-drive-the-planet-into-an-ice-age/
http://www.abc.net.au/science/articles/2012/09/20/3594552.htm
http://www.space.com/17676-comet-crash-ice-age.html
Vesta:
http://news.discovery.com/space/protoplanet-vesta-awash-in-hydrogen-120920.html
http://www.space.com/17680-giant-asteroid-vesta-hydrogen-dawn-spacecraft.html
MACS J1149-JD:
http://www.space.com/17671-farthest-galaxy-discovery-gravitational-lens.html
http://en.wikipedia.org/wiki/Epoch_of_reionization
Curiosity:
http://www.telegraph.co.uk/science/space/9554550/Nasas-Curiosity-rover-to-begin-Martian-rock-studies.html
http://www.huffingtonpost.com/2012/09/18/mars-eclipse-curiosity-martian-moon-phobos_n_1892951.html

Description: In this month’s episode of the Monthly News Roundup, a rock hits Jupiter and a bunch once hit the Earth. Dawn reveals startling new information about the asteroid Vesta. The oldest ever galaxy is discovered and NASA”s youngest rover flexes its muscles.

Bio: Morgan Rehnberg is a graduate student at the University of Colorado – Boulder, where he studies the rings of Saturn under the direction of Dr. Larry Esposito. Morgan received his B.S. in Physics from Beloit College and is the developer of the PhAst software package for the viewing and manipulating of astronomical images

Today’s Sponsor: This episode of 365 days of Astronomy is sponsored by iTelescope.net – Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia.

Transcript:

Welcome to the 365 Days of Astronomy Podcast for September 28th, 2012.  I’m Morgan Rehnberg and this is the Monthly News Roundup.  This episode was recorded September 23rd in Boulder, Colorado.

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Our top story this month is the unexpected sighting of an impact on the surface of Jupiter.  First spotted by Wisconsin amateur astronomer Dan Peterson, the September 10th impact was recorded on video by Texas amatuer George Hall.  Astronomers around the world searched eagerly for an ‘impact scar,’ the disruption pattern left by the object as it plunged through Jupiter’s atmosphere.  Unfortunately, telescopes such as NASA’s Infrared Telescope Facility were unable to detect the aftermath of this small impact.

Such impacts illustrate the vital role that amateur astronomers play in planetary observations.  Since the break-up of comet Shoemaker-Levy 9 in 1994, only four impacts have been observed in the atmosphere of Jupiter; all of which have been initially discovered by amateurs.  These dedicated observers provide a valuable service to the budget-constrained astronomical community: nearly continuous observations of Mars, Jupiter, and Saturn.

Although once thought rare, astronomers now believe that small impacts on Jupiter are a regular occurrence. Jupiter’s large mass and proximity to the asteroid belt probably contribute to this. In the past, Jupiter has likely helped shield the Earth from similar harmful impacts.

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From impacts on Jupiter, we move to the past effects of impacts here on Earth. Scientists have believed for decades that a major asteroid impact 65 million years ago likely wiped out the dinosaurs, making way for mammals to become some of the most dominant species on the planet. Evidence now suggests that similar, albeit smaller, impacts maybe have influenced Earth’s climate several times since then.

Most substantially, a meteor, named Eltamin after the survey ship which discovered its crater, may have plunged the planet into a substantial ice age approximately 2.5 million years ago. Recent computer simulations created by a team out of Australia’s University of New South Wales suggests that the two-kilometer sized impact may have created a tsunami which spread across much of the world’s oceans. More damagingly, such an impact probably ejected a significant amount of debris into the atmosphere, blocking some of the Sun’s heat and kick-starting the most recent major ice age.

New evidence has also emerged that a smaller impact may have killed off many of North America’s largest animals near the end of the Ice Age. A new report released in the Proceedings of the National Academy of Sciences corroborates finding first released in 2007, which claimed that an impact in northern Canada about 12,900 years ago killed off most of the continent’s woolly mammoths and saber-toothed tigers. Early man was not spared either; this date corresponds with the disappearance of Clovis culture – a recently arrived group of stone-age humans.

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More rocky news this month comes from the asteroid Vesta, the second largest member of the asteroid belt. Vesta has been extensively studied by the Dawn spacecraft since it’s arrival in July of 2011. Two studies released this month in the journal Science suggest that Vesta may be more connected to the Earth than previously thought. The spacecraft detected unexpectedly-high levels of hydrogen on the asteroid’s surface. Although hydrogen is the most abundant element in the universe, it’s light, gaseous nature means that when the solar system first formed, hydrogen was concentrated mostly in the large, outer planets. Vesta, which like Earth formed in the early years of the solar system, probably wasn’t born with much of the gas. This suggests that, like Earth, Vesta probably received much of its supply in collisions with water-rich comets during the intervening eons.

The second study suggested an even more direct link between Vesta and the Earth. Detailed studies of the asteroid’s surface composition reveal a chemical makeup that appears remarkably similar to a class of meteorites discovered on Earth. These meteorites, known as HEDs, must have been knocked off of Vesta during collisions with other asteroids. These sheared off chunks eventually made their way to Earth, where they were eventually picked up by scientists. The presence of these samples means that we can now directly study the composition and structure of Vesta in laboratories here on Earth. The combination of laboratory examination and spacecraft sensing should provide a unique view of Vesta.

Despite the importance of these findings, Dawn’s mission is not over. On September 5th, the spacecraft left Vesta’s orbit and is now headed towards Ceres, the solar system’s largest asteroid. It is expected to arrive in February of 2015.

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New observations by the Hubble and Spitzer Space Telescopes have revealed the farthest-ever detected galaxy. The galaxy, given the technical name MACS J1149-JD, formed less than half a billion years after than Big Bang.

Objects which are so far away are naturally very dim. Scientists had to use the technique of gravitational lensing to detect this galaxy. Gravitational lensing is an effect of Einstein’s theory of General Relativity. General Relativity shows that objects with mass physically curve the space around them. For everyday objects, this curvature is undetectably small, but if enough mass is gathered in one place, the curvature can be large enough to visibly affect the path of light. In gravitational lensing, an intermediate mass bends the light of a fainter, more distant object towards the Earth, making it seem temporarily brighter. In order to detect MACS J1149-JD, scientists had to wait until an entire galaxy cluster provided enough mass to brighten the galaxy to levels visible from Earth. Even still, it took two of the most powerful telescopes to catch a glimpse.

These observations are important because they allow astronomers to peer back into the Epoch of Reionization, one of the least-understood periods of the universe’s evolution. Prior to reionization, nearly all the matter in the universe consisted of inert molecular hydrogen. During the Epoch of Reionization, which occurred between roughly 150 million and a billion years after the Big Bang, intense radiation broke apart hydrogen into the protons and electrons which make it up. This allowed for new and more complex chemistry to occur.

MACS J1149-JD should provide us with an unprecedented window into this world, but additional observations will continue to experience difficulties caused by this galaxy’s extreme distance.

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We end this month by checking in with NASA’s Curiosity rover as it begins its journey on the surface of Mars. As the rover drives towards its first target, it continues to test out its various instruments after the bumpy descent to the Martian surface. Central among these is Curiosity’s robotic arm. The arm allows the rover to reach out to nearby rocks and includes a suite of instruments and a camera. A pause in its schedule allowed the rover to peer underneath itself and photograph its underbelly for engineers at NASA’s Jet Propulsion Laboratory to examine.

The rover will get to put its arm to full use for the first time in the upcoming days as it examines a strange rock it encountered on one of its drives. Shaped like a pyramid, the rock is larger than those typically encountered thus far. The rock will be photographed, examined with X-rays, and bored into with a small laser. Project scientists have no specific expectations, but surprises have occurred during similar observations by the Mars Exploration Rovers in the past.

Curiosity also put its main cameras to good use this month as it looked skyward to capture the first ever images of a solar eclipse from another planet. On September 13th, Phobos, the larger of Mars’ two moons passed partially in front of the Sun. Not nearly as large as Earth’s moon, Phobos blocked only a small portion of the Sun’s light, but the eclipse provides a unique opportunity to study the asteroid-like moon.

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Thanks for listening to September’s Monthly News Roundup. As always, you can contact me at Morgan.Rehnberg@colorado.edu with your comments and corrections. See you next month!

End of podcast:

365 Days of Astronomy
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