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Volcanism on Icy Io July 20, 2012

Posted by epscienceblog in Astronomy, moon, Solar and Space weather.
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Io, the closest moon to Jupiter, has an orange-brown
surface containing sulfur, the light areas are an icy
mix of sulfur and the dark areas highlight volcanic areas. Composite picture from NASA

As we have studied the Universe, one of the main ways that we have learned in the past is by using the Earth as a comparison, using all that we know about our planet as a reference for the other galactic bodies that we explore.  What is amazing now is the shift that is taking place, where we are beginning to use what we learn about other celestial bodies and apply that information to our own planet.  We learn even more about Earth as advances are being made in the exploration of our universe.  One example of how we are applying our knowledge of other bodies is Io.  The new information that is being gained from Io gives clues to the processes that occurred on Earth when it was young.

Io is an icy satellite of Jupiter 628,866,000 km from Earth, far enough from the sun that its surface temperature is 175 K (-143°C or -230°F) and is covered in sulfur dioxide frost.  Io’s yellow tinged crust is not fractured, therefore, it is not thought to have tectonic activity.  Despite these two factors, Io has the most volcanic activity in our solar system, spewing out over 100 times as much lava as all Earth’s volcanoes combined and may have as many as 300 active volcanoes.

Image from New Horizons, highlighting the Tvashtar volcanic plume reaching 300 km above the horizon.
Credit: NASA

The surface of Io is much different than previous expectations had dictated, and contains potential clues to the history of Earth.  When the Voyager spacecraft missions took images of Io in1979, NASA was surprised to see that Io was not full of craters, as had previously been thought.  It was assumed that Io would be cratered much like our moon.  Yet Io hardly had any craters at all, instead it had irregular pits and blotches of color.  When the images were carefully examined, volcanic plumes and lava flows were discovered.  Infrared spectrometry also detected abundant sulfur and sulfur dioxide in the volcanic plumes.

The sulfur on Io’s cold crust is solid, though when heated inside the crust, it explodes much like steam in a geyser on Earth.  The sulfur cools as it is ejected and may fall back down as “snow” on Io’s surface.  The lava flows on Io can range in color from orange to red to black and are found around the active vents.  The Galileo spacecraft monitored volcanic areas in the late 90s and found that the active lava flows of Io were between 1700 to 2000 K (around 1450 to 1750°C, or 2600 to 3150°F).  Earth’s lava temperatures are around 1300 to 1450 K.  The lava on Io is probably ultramafic, containing magnesium and iron that have higher melting points.  Ultramafic lava is found on Earth, but was formed when the Earth was young and the interior was much hotter than today.

A blue-tinged volcanic eruption forcing out rock and sulfurous gas,
taken from the NASA Galileo spacecraft.

The volcanoes on Io are mostly caldera-like, containing  large pools of lava, though some are fissures or cracks where the molten material can flow over the surface.  Loki Patera is a caldera with a diameter of 200 km, which makes it the largest in the solar system.  Some of the volcanoes form fountains, umbrella-shaped flows that spread up and out over large distances.  The Prometheus plume is a volcanic region that has been seen in almost every image taken of Io from 1979 to 1997, suggesting that it has been continually erupting for years.

Jupiter’s four largest moons (from left to right: Io, Europa, Ganymede, Callisto)
with sizes to scale. Credit: NASA

Aside from the similarities, we can also learn from the stark differences between Earth and Io.  While the heat in Earth’s core is mainly due to the radioactive decay of uranium, thorium and potassium, Io’s extreme internal temperature is caused by gravity.  Io is the closest natural satellite to Jupiter and is one of Jupiter’s four largest moons.  Due to the close proximity to Jupiter and the slightly elliptical orbit of Io, the gravitational pull on Io ebbs and flows, creating contraction and expansion on Io’s crust.  The next two moons closest to Io, Europa and Ganymede, also interact gravitationally with Io and increase the forces on Io as they routinely pass by.  The speed of the moon’s orbits are not the same; during the same period of time Ganymede orbits once, Europa orbits twice and Io orbits four times around Jupiter.  The differences in the orbits cause the moons to line up often.  This increases the gravitational pull on Io from both Europa and Ganymede as well as from Jupiter.  This continual pull creates tidal heating causing temperatures that melt the rock within Io and fuels the intense volcanic activity.  The process of squeezing and flexing is similar to how a ball of clay will soften and warm as a person kneads it.  However, the heating of Io is unlike what we have ever experienced on Earth.  The tidal heating on Io adds as much energy as 24 tons of TNT exploding every second.  Io’s surface receives 2.5 watts of power to each square meter, compared to 0.06 watts per square meter on the Earth’s crust from global heating.  The only areas on Earth that are comparable to Io’s average are in Earth’s volcanic areas.

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April Podcast: The Moon’s Mysterious Exosphere April 23, 2011

Posted by jcconwell in moon, Podcast.
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http://365daysofastronomy.org/2011/04/20/april-20th-the-moons-mysterious-exosphere/

Description: It is commonly thought that the moon has no atmosphere – we hear how the Apollo astronaut’s footprints are undisturbed because there is no atmosphere or weather on the Moon to precipitate any changes, but we now know that the Moon actually does have an extremely thin exosphere. With us today is Brian Day, the Education and Public Outreach Lead for NASA’s upcoming LADEE mission, and with the NASA Lunar Science Institute.

Bio: The NLSI brings together leading lunar scientists from around the world to further NASA lunar science and exploration.

Brian Day is the Education and Public Outreach Lead for NASA’s upcoming LADEE mission, and works with the NASA Lunar Science Institute.

Nancy Atkinson is a science journalist and is the Senior Editor for Universe Today

SOLSTICE LUNAR ECLIPSE December 19, 2010

Posted by jcconwell in Astronomy, moon.
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On Dec. 21st, the first day of northern winter,  the full Moon passes almost dead-center through Earth’s shadow. For 72 minutes of eerie totality, an amber light will play across the snows of North America, throwing landscapes into an unusual state of ruddy shadow.

The eclipse begins on Tuesday morning, Dec. 21st, at 12:33 am CST (Monday, Dec. 20th, at 10:33 pm PST). At that time, the moon passes through the Earth’s shadow, will appear as a  bite at the edge of the lunar disk. It takes about an hour for the shadow  to expand and encompass the entire Moon. Totality commences at 01:41 am CST (11:41 pm PST) and lasts for 72 minutes.

For the best time for a quick look on a cold night –  it is December, after all –  choose this moment: 01:17 am CST (17 minutes past midnight PST). That’s when the Moon will be in deepest shadow, with a deep red color.

Why the deep red color? If you were on the moon you’d see the Earth cover the Sun, but instead of seeing black, you’d see the remaining sunlight pass through the Earth’s atmosphere around the Earth’s rim. A world wide sunrise or sunset. The light passing through so much atmosphere causes Raleigh scattering. The blue light is scattered out, causing the blue skies we see on Earth. What is left over is the red. Red sunsets, and red light hitting the moon, causing it’s deep scarlet glow.

Astronomy Club Movie and Pizza Tonight! December 1, 2010

Posted by jcconwell in General, moon.
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Hello all!  We will be having our annual Astronomy Club movie and pizza night this Wednesday 12/01/10 in room 2153 of the physical science building at 8:00pm.  We will be watching the movie “Moon” and eating pizza and having good times.  Bring friends if you like!  Hope to see you all there!

Lcross, the next Day…Not everything you can see is visible. October 10, 2009

Posted by jcconwell in Astronomy, moon.
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Visible light that is. For humans that’s from 380nm to 740nm in wavelength. If you’ve been watching the news, you know that the Lcross lunar impacts did not give off a spectacular plume that would be visible to the many amateurs. Heck, not even the Hubble space telescope or Mt. Palomar saw anything in the visible. I take a small consolation, since the EIU observatory was clouded over and I was home drinking a cup of coffee and watching NASA TV.

But sometimes visable is not where the action is, Infrared and ultraviolet are, as you can see below.

The picture below is from The Planetary Society Blog By Emily Lakdawalla

Uncalibrated Diviner thermal maps of the LCROSS impact region Credit: NASA / GSFC / UCLA

Uncalibrated Diviner thermal maps of the LCROSS impact region Credit: NASA / GSFC / UCLA

Pictured above is the preliminary, uncalibrated Lunar Reconnaissance Orbiter Diviner thermal (infrared) maps. These four channels operate in a band from 12.5nm to 200nm in the infrared.  Look for the small dot just below the center. The impact site pictures were acquired two hours before the impact, and 90 seconds after the impact.The detection is consistent with the notion that the LCROSS impact resulted in significant local heating of the lunar surface.

View the Lcross Lunar Impact October 8, 2009

Posted by jcconwell in Astronomy, moon.
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Guide to Lcross Impact Site

Guide to Lcross Impact Site

When: Following the latest trajectory correction maneuvers, the time of impact on Friday, October 9, 2009 is 11:31:19 UTC for the Centaur and 11:35:45 for LCROSS spacecraft.

7:31:19 a.m. EDT and 7:35:45 a.m. EDT.

6:31:19 a.m. CDT and 6:35:45 a.m. CDT

5:31:19 a.m. MDT and 5:35:45 a.m. MDT

4:31:19 a.m. PDT and 4:35:45 a.m. PDT

But if your area is going to be cloudy you can see it live on NASA TV http://www.nasa.gov/multimedia/nasatv/index.html

For a more detailed guide to tomorrow morning event go to the article at Universe Today


New Podcast on Saturn’s Moon Enceladus August 28, 2009

Posted by jcconwell in Astronomy, IYA 2009, moon, planets, Podcast.
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The podcast  for today  at “365 days of astronomy” is sponsored by the Physics department at EIU. This podcast covers the history, current understanding, and upcoming plans for Enceladus, and is moderated by David Seal, Cassini Mission Planner at NASA’s Jet Propulsion Laboratory.

365_iyaThe permanent link is at

http://365daysofastronomy.org/2009/08/28/august-28th-saturn’s-moon-enceladus-–-past-present-and-future/

New Podcast is up at 365 days of Astronomy July 21, 2009

Posted by jcconwell in Astronomy, IYA 2009, moon, Podcast.
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365_iya

A change in the date of our sponserd podcast to TODAY. Link is at:

http://365daysofastronomy.org/2009/07/21/july-21st-astronomy-in-anglo-saxon-england/

Yes!! We really did land on the Moon 40 years ago,Today! July 20, 2009

Posted by jcconwell in Astronomy, IYA 2009, moon, Space Craft.
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Forty years ago today Apollo 11 landed on the moon. When I have an open house at the observatory, one of the things people want to know is, can we see the landers that are left on the moon from the Apollo missions. I have to tell them no, too much atmosphere, and not enough telescope.

The scary thing is the 6% of the public who believe the landing was all just one big hoax. Now to answer both questions on the 40th anniversary…we’ve got pictures!!!!

All images credit: NASA/Goddard Space Flight Center/Arizona State University

NASA’s Lunar Reconnaissance Orbiter, or LRO, has returned its first imagery of the Apollo moon landing sites. The pictures show the Apollo missions’ lunar module descent stages sitting on the moon’s surface, as long shadows from a low sun angle make the modules’ locations evident.

The satellite reached lunar orbit June 23 and captured the Apollo sites between July 11 and 15. Though it had been expected that LRO would be able to resolve the remnants of the Apollo mission, these first images came before the spacecraft reached its final mapping orbit. Future LROC images from these sites will have two to three times greater resolution.

Apollo 11 Site, Click for Larger picture

Apollo 11 Site, Click for Larger picture

The Apollo 14 site shows even more detail in the full picture below and the magnified Captions

Apollo 14 Landing Site

Apollo 14 Landing Site

Apollo 14 Site showing foot path and instruments

Apollo 14 Site showing foot path and instruments

These pictures are reminder of a past era of NASA exploration, but the LRO’s mission is paving the way for the future. By returning detailed lunar data, the mission will help NASA identify future landing sites robots and astronauts, locate potential resources,like water, and measure the moon’s radiation environment while testing new technologies.