QUEST Community Science Blog Author: Ben Burress

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Probing the Martian Pole

May 9th, 2008 by Ben Burress

Mockup of Phoenix (top) and ‘Robinson Crusoe on Mars’
(bottom)—both set in Death Valley National Park…
Credit: NASA (top), Paramount Pictures (bottom)It’s that time of the Martian year again: when a flying saucer from Earth appears in the skies of Mars. Imagine if there actually were Martians up there: what’s science fiction here on Earth would pass for reality on the Red Planet—and a routine occurrence at that!

This time the flavor of the day is the Phoenix Lander, courtesy of NASA, scheduled to land on May 25th at about 4:38 PM PDT. We’ll be watching live NASA coverage of the landing at Chabot Space & Science Center that afternoon, if you’d care to join us…

Following somewhat in the footsteps of the Viking landers of the 1970s, Phoenix’s primary mission is to look for evidence of life, or at least the chemical conditions that might be suitable for life to exist. The two Viking landers carried small chemical laboratories that analyzed soil samples scooped up from the surface, as does Phoenix.

While its mission parallels that of Viking, one big difference from Phoenix is its destination: the Northern Polar Ice Cap of Mars. The Vikings landed much farther south in the mid latitudes. Phoenix is targeting the ices of Mars’ arctic region.

Growing up, one of my favorite sci-fi films was Robinson Crusoe on Mars. Made in 1964, the same year that Mariner 4, the first space probe to Mars, was launched, RCOM made a descent stab at imagining what it was like. So what if the main character walked around in apparent t-shirt weather and with sufficient atmospheric pressure to keep his blood from boilin–he still wore a respirator that doled out oxygen from an ever-dwindling supply tank, a nod to Mars’ thin atmosphere.

A couple of other things our astronaut Robinson Crusoe found on that fictional Mars that we are now looking for on the real one: liquid water and life…Our hero found small caches of water (with the help of a monkey) in grottos between the rocks, and, lo and behold, living in that water was a vine-like life form with edible fruit or tubers. He even took a foot-trek, along with his guy Friday, to the polar ice cap…

(I also loved the film because some of its “Martian terrain” scenes were shot in my favorite spot on Earth, Death Valley…)

Though evidence of past liquid water action seems to be all about the planet, Phoenix certainly won’t find any brooks or pools or grottos of spring water, owing at least in part to the frigid arctic region it will set feet on–an arctic zone on a world where the warmest temperatures in the tropics might reach levels of the coldest climates on Earth. What’s important about landing on Mars’ ice cap is that Phoenix is almost certain to dig up some water–albeit frozen.

And it is the chemical compounds either locked up in that ice or preserved by its proximity that Phoenix is interested in. (Similarly, climatologists on Earth study ice cores from Antarctica to analyze the trapped and preserved gases of Earth’s atmosphere of past millennia.)

We wish Phoenix a happy landing, and look forward to the first images and discoveries from the Martian North Pole. And I’m fairly confident the epic polar adventure ahead won’t resemble in the least another “great” film of 1964: Santa Claus Conquers the Martians….

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.





Tags: death valley, KQED, Mariner 4, mars, Mars Northern Polar Ice Cap, Phoenix, Robinson Crusoe, Science, Viking landers



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Cassini Martini: Add Water, Ammonia, Methane; Mix Well

April 25th, 2008 by Ben Burress

Artist concept of a geyser erupting on Enceladus.
Credit: David Seal.Back when I was young…okay, a previous generation might have ended that sentence with, “…I’d walk forty miles through the snow to get to school…” But I’m not exaggerating when I say, when I was young we knew next to nothing about faraway places in the Solar System…such as the moons of Saturn.

A layer of the veil around Saturn’s moons was removed when Pioneer 11 and Voyagers 1 and 2 made flybys of Saturn in the ’70s and ’80s. The Saturnian moons, it appeared, were not the lumps of rock and dust that Earth’s own Moon is made of, but objects containing no small amount of water ice. Not terribly surprising, considering the low temperatures of the outer solar system where ice-rich comets roam.

Visions of frozen alien landscapes, replete with icicles and ice cliffs and ice fields and ice ice ice! were conjured in my imagination, and in artist depictions of majestic ringed Saturn seen from moons like Rhea or Dione or Enceladus.

Four years ago, Saturn’s first permanent visitor from Earth–the Cassini spacecraft–arrived there, and since has been making extreme closeup examinations of Saturn, its rings, and its increasingly wondrous and beautiful moons. Cassini is almost literally ripping apart veil after veil of our ignorance of these little worlds.

Far from a contingent of enormous but simple snow cone balls, Cassini has shown us that some of Saturn’s moons are apparently alive with liquid motion. First, there were the surface “lakes” and “seas” on Titan, probably made of extremely cold liquid hydrocarbons like methane and ethane–the stuff that spouts out of the gas range in your kitchen. Lakes and seas and rolling waves of liquid natural gas are fine and dandy for an imagined shoreline scene–but take a dip in those “waters” and an actual water-based creature like you would freeze solid in seconds. Scenic, but not inviting for a swim…

But recent observations by Cassini have shown that Titan’s frigid unearthly lakes and Enceladus’ snowball exterior may just be additional veils that are now being lifted.

In March, Cassini flew within 30 miles of the surface of Enceladus and right through a plume of material venting into space from the moon’s interior—an enormous “geyser.” Earlier observations had sensed the presence of water in the plume, giving rise to speculation that liquid water in some form might exist beneath Enceladus’ surface—perhaps chambers of liquid heated by tidal stressing of the interior.

When Cassini flew through the plume, its chemical sensors “sniffed” more than just water in the stream, but a good deal of organic molecules as well…not unlike material found in comets, stuff left over from the formation of the Solar System that may have been the building blocks of life on Earth.

The other “water find” was that of a possible liquid ocean under the crust of Titan–similar perhaps to the deep liquid water ocean believed to exist under the surface of Jupiter’s moon Europa. Unexpected “drift” in the locations of landmarks on Titan’s surface is what suggests a liquid ocean–water with perhaps some ammonia–that the frozen crust may be floating on.

With all the liquid water and organic chemistry being revealed in the Saturn system (and elsewhere in the outer solar system), our imaginations can shift from the older standards of envisioning otherworldly landscapes of sculpted ice or even seascapes of liquid hydrocarbon lapping on shores of water ice sand, to something a little more, shall we say, “lively…”?

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.





Tags: Cassini, Chabot Space Center, Enceladus, KQED, Saturn, Saturn's moons, Science, Titan



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The Last Hoorah for Solar Cycle 23?

April 11th, 2008 by Ben Burress

Magnetic activity on March 27th; white indicates N
magnetic poles, black S. Credit: ESA/SOHO/NASA.

A few blogs back I wrote about the 11-year cycle of ups and downs in solar activity–the Solar Cycle –and how over the last year or so the baton was supposedly passed from Cycle 23 to Cycle 24. But there has been an occurrence on the Sun that suggests we may be in somewhat of a gray zone….

For the past two or three years, the Sun has been downright boring. We set up our Sunspotter telescopes for visitors and try very hard to make what we see seem interesting–”See that perfectly blank circle of light? That’s the Sun! Really it is!”

About a week ago, the tedium was suddenly broken by a train of sunspots that rotated into view on Sun’s disk. Five–count’em– five sunspots! Finally, something to actually look at! And in the eyepiece of our Coronado Hydrogen-Alpha filter telescope there were filaments and plage! What are filaments and plage? Exactly! People wanted to know….

Then came the weird part: these were not Cycle 24 sunspots (I am not the Dread Pirate Roberts…); they were refugees from the supposedly defunct Cycle 23. While the distinction may be a fine point that doesn’t worry most of our visitors, it can still be a good talking point.

So, why were these five sunspots fingered as old solar trekkers rather than members of the next generation? It all comes back to what a solar cycle is–and sunspots, flares, prominences, and plage are merely details: manifestations of the Sun’s magnetic convulsions. The Sun, like the Earth, generates an enveloping magnetic field–a big donut with a north and a south magnetic pole. On smaller scales there are plenty of twists and swirls and knots in the field caused by local “hot spots” of magnetic activity–which are what produce features like sunspots in the first place.

At solar maximum–the peak of activity of a solar cycle–the Sun’s magnetic poles flip over, or reverse. In fact, it’s this reversal that really lets us know when a solar maximum has arrived. (Earth’s magnetic field also reverses polarity periodically–although this only happens every 200,000 years, on average.)

At the beginning of a solar cycle, new sunspot activity can be found at high solar latitudes, and as the cycle progresses, activity migrates toward the equator. On a finer nuance, the magnetic polarity of sunspots–which can be N or S, and are usually paired up, like the two ends of a bar magnet –are typically oriented east-to-west on the Sun’s surface, one leading to the other as the Sun rotates. Which type of pole (N or S) leads and which trails depends on the overall magnetic “flip” state of the Sun’s magnetic field.

To round out this report, the five surprise sunspots of yesterweek were lined up close to the Sun’s equator, and the orientation of their magnetic poles bespoke their affiliation with the outgoing magnetic administration (Cycle 23). So far, only a single, high-latitude, reverse-polarity sunspot observed last January has signaled Cycle 24 .

Who knows? Maybe the magnetic candidates of Cycle 24 are still holding primaries, caucuses, and debates and have yet to begin some serious campaigning…

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.





Tags: KQED, magnetic pole, Science, solar activity, Solar Cycle, sun, sunspot



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Living in the Sun's Atmosphere

March 28th, 2008 by Ben Burress

Illustration of a blast of solar wind impacting
Earth’s protective magnetic field. Credit: NASABreathe in, exhale. Feel the air in your mouth, windpipe, and lungs. That’s a sample of Earth’s atmosphere: the thin layer of gases enveloping our planet.

Did you know that the Sun also has an atmosphere, and that the Earth is inside it? In fact, the Sun’s envelope of gases extends well beyond the orbit of Pluto, out to the regions of the solar system where the 3-decade-old Voyager spacecraft are only now reaching.

“Space weather” refers to the conditions in space caused by the outflow of electrically charged gases (plasma) coming from the Sun—what we call the “solar wind.” The term “space weather” may conjure images of cosmic tornadoes, astral lightning bursts, and some Star Trek version of a galactic hurricane– but actual space weather is nothing so Earthly and familiar.

First of all, the “air” in space is nothing like the atmosphere we draw our breath from. Earth air, at the surface, is made of nitrogen, oxygen, argon, carbon dioxide, water vapor, and other trace elements, and is relatively dense. “Space air” is mostly hydrogen– ionized hydrogen at that (meaning stripped of its electrons and so electrically charged; the separated electrons are also blowing along in the solar wind).

Second, the gases of the solar wind are extremely rarified. Despite the talk of a solar atmosphere, solar wind, and space weather, space within the solar system is still almost a complete vacuum. At Earth’s distance from the Sun, the average density of the solar wind is somewhere between 6 and 9 atoms (mostly hydrogen) per cubic centimeter. If you spread out the gas contained in an ordinary party balloon to this same thinness, it would fill a volume of space over 10 miles across!

Third, the solar wind, for all its sparseness, blows fast! Depending on conditions of space weather, the flow of solar wind past the Earth can speed along anywhere from 200 to 900 kilometers per second! Earth’s fastest winds slug along at only a few hundred kilometers per HOUR.

So how does space weather—the changing conditions of the solar wind—affect us on Earth? How might you, personally, have experienced, directly or indirectly, the effects of the Sun’s gentle breeze?

The most familiar phenomenon caused by space weather is Earth’s beautiful auroras —the northern and southern lights. Interactions between the solar wind and Earth’s magnetic field and electrically charged particles trapped in it excite atoms in the upper atmosphere to emit light. And it’s not just a softly glowing night light: the most powerful auroras can generate up to a trillion Watts of power!

Solar wind “storms” can not only produce more active auroras, but can cause fluctuations in Earth’s magnetic field whose effects can be felt on the ground. These “geomagnetic storms” usually pass unnoticed, perhaps causing a tiny change in the direction that compass needles point– but have also been known to overload electrical power grids and cause blackouts.

In the space around Earth, solar storms have been known to damage or disable satellites, and can put unprotected astronauts at risk. Space walks on the International Space Station are scheduled for times when space weather is - so to speak -”sunny and calm.”

Thinking about space weather on Earth might seem like worrying over Atlantic hurricanes here in the Bay Area—but with more and more human activity taking place beyond the confines of our atmosphere, this is a very real and vital concern, and is taken very seriously.

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.




Tags: Astronomy, atmosphere, chabot, KQED, Science, solar energy, solar wind, sun, sunspot



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Equinox Season

March 14th, 2008 by Ben Burress

It’s approaching that time of year again: Spring Equinox. The blaze in my home’s interior hallway has been signaling this for the last week.

The shadow of Chabot’s “solar clock” at noon
on the equinox produces a pattern of solid green
straddling the gnomonI noticed late in the afternoon a couple days ago that the windowless hallway where we hang all of our family photos was afire in a shaft of bright sunlight, entering a window in the adjacent bedroom. Only around Equinox (Spring or Fall), when the Sun sets about directly west, does this happen in my house. The rest of the year the Sun sets too far north or south for this window-and-hallway alignment to take place. It’s a striking event because for only a few days of the year my normally dark hallway explodes with radiance.

Ancient cultures all around the world made use of the changing rise and set position of the Sun to track the seasons, and either observed special alignments of sunlight and shadow with geographical features, or built structures that made the special alignments. Stonehenge is one famous example, but there are plenty of other seasonal observatories in just about every part of the world.

Unlike the more distant stars in the sky, which always rise and set at the same points on the horizon, the Sun (a star too, of course) wanders northward and southward in the sky throughout the year, and so its rise and set points migrate. On the Equinoxes the Sun rises directly at the east point on the horizon and sets directly at the west point-but at Summer Solstice in the Bay Area it rises a full 30 degrees to the north, and at Winter Solstice 30 degrees to the south.

The reason for the Sun’s annual wandering comes from the tilt of Earth’s rotational axis with its orbit around the Sun. At our (Northern Hemisphere) Summer Solstice, our hemisphere is tipped toward the Sun and the Sun appears at its most northerly point in the sky; we receive more hours of sunlight and more direct rays from the Sun-so it’s warmer. Winter Solstice is opposite, with our hemisphere tipped away and the Sun and the Sun farthest to the south, making for shorter hours of daylight and less direct solar rays–and so it’s colder.

Equinox is a middle point between solstices: the Sun is poised between the northern and southern extreme points of the solstices-positioned directly over Earth’s equator-and the hours of daylight and night are about equal.

Does your home or place of work function as a solar seasonal calendar, as mine does? Is there a special time of year when you notice a striking pattern of light and shadow, a special alignment of walls, windows, doors, or other features? From the location of Chabot Space & Science Center, at equinox the Sun sets directly on the Golden Gate Bridge… .

If you have noticed something like this, then you’ve experienced what many ancient peoples noticed about the seasonal changing of the Sun. Their observations led them to understanding, or at least making use of, the cycle of the Earth revolving about the Sun to establish the earliest calendar systems.

Take a look and see what you notice, especially around Equinox (March 19, Pacific Time-March 20 GMT).

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.




Tags: Astronomy, chabot, equinox, gnomon, KQED, kqedquest, oakland, observatory, pbs, QUEST, Science, solar clock, stonehenge



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Oakland’s Observatory

February 29th, 2008 by Ben Burress

The original Oakland Observatory in the 1880’s,
at Lafayette Square in Oakland. Credit: Chabot Space
& Science Center archives.This year marks an anniversary for the astronomical heritage of Oakland and the San Francisco Bay Area: Chabot Observatory turns 125!

Originally established as the Oakland Observatory in 1883, the facility was a unique creature from the very beginning. Conceived by then Oakland Public Schools Superintendent Jewett Gilson, who was inspired by a school observatory he saw in Philadelphia, the observatory was created for use by Oakland schools and the general public at large.

Gilson looked for, and eventually found, a donor to fund the observatory project: Anthony Chabot, a wealthy entrepreneur and philanthropist who made his fortune building municipal water systems in the Bay Area– including Lake Temescal and Lake Chabot. Anthony Chabot stipulated as part of his original $3,000 gift that the telescope shall forever be available for public observation at not cost– a tradition that continues today.

Chabot didn’t want the observatory to be named for him, so in its earliest years it was called the Oakland Observatory. The public, as the story goes, insisted on calling it Chabot Observatory in gratitude for the gift– and eventually the name was made official.

The original location for the observatory and its 8-inch Alvan Clarke and Sons telescope (”Leah”) was close to downtown Oakland in Lafayette Square– which today remains a square block of parkland, at 10th and 11th Streets and Martin Luther King Junior Way and Jefferson Street. In those days, 10 or so visitors on any given night would climb the tower-like structure to the telescope dome and peer at the heavens through the high quality instrument. Reservations had to be made in advance– sometimes as long as a month or two.

As Oakland grew, and particularly as it converted its street lighting from gas-powered lamps to electric lights, the necessity of moving the observatory to a darker spot grew. The observatory’s first director, Charles Burckhalter (who is said to have been the first person in Oakland with an astronomical telescope, set up in a backyard observatory at his home on Chester Street), arranged for the relocation. A number of different sites were considered– including a spot near Redwood Peak, the current location of the observatory– but a small hill next to the Mills College campus was finally adopted.

In 1915, Chabot Observatory opened at its new site, along with a new 20-inch Warner and Swasey telescope (”Rachel”), and continued to wow the public with the astronomical vistas it conveyed. In 1923 the directorship passed to Earle Linsley, a Mills College professor, who expanded the reach of the observatory to the public through outreach to schools and the establishment of an amateur astronomy group (today the Eastbay Astronomical Society).

Having visited this Chabot Observatory as a child in the 1960s, I now appreciate how long and distinguished a career those two telescopes spanned. At the time, I had no idea that Leah, even in 1968, was 85 years old-older than my grandparents! Then the observatory was run by the beloved Kingsley Wightman — “Mr. Science” to a generation or two.

It took the moving Earth to relocate the observatory a second time– literally. Because of Chabot Observatory’s location almost directly on top of the Hayward Fault, and the fact that the aging buildings were not quake– safe in the first place, another site had to be found: the present location of Chabot Space & Science Center, adjacent to Redwood Peak.

Happy 125th to Oakland’s special connection with the stars!

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.


Tags: Astronomy, chabot, KQED, oakland, observatory, Science, space, telescope



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Nap time for the Sun: solar cycles

February 15th, 2008 by Ben Burress

Extreme close-up of the Sun’s visible surface,
showing ‘bubbling’ cells of convecting gas–each the size of
Northern California. credit: Hinode JAXA/NASA/PPARCBy all accounts, a new cycle-Cycle 24-in solar activity has begun… something you probably didn’t notice since the beginning of a solar cycle is quite subtle….

First things first: what is a solar cycle, and why is this one number 24? You’ve probably heard of sunspots and solar flares and disturbances in radio communications caused by solar activity, but had you noticed NOT hearing much about these things in the last two or three years?

The Sun exhibits a cyclic rise and fall in its level of magnetic activity. Being an enormous ball of roiling, circulating plasma (electrically charged gas), the Sun generates powerful magnetic fields in a way similar to how the circulating electricity in an electromagnet creates one.

Over the course of a solar cycle, the intensity and amount of magnetism generated by the Sun increases, like soup warming up on the stove, reaching a violent climax in which twisting, tangling magnetic fields break loose and release their energy in the form of solar flare explosions, coronal mass ejections, and tremendous heating of the solar atmosphere.

Sunspots are surface features formed by the presence of strong magnetic fields, and in general the number of sunspots that can be seen and counted indicate the level of magnetic activity on the Sun. For 400 years, since Galileo first started counting sunspots through his telescope, observers have kept track of sunspot counts, and over time a pattern in their number emerged. On average, the number of sunspot activity peaks every 11 years at a time called solar maximum.

I remember when I first started working at Chabot Space & Science Center, back in 1999/2000, during the last solar maximum. Using our Sunspotter telescopes on public observing days, in teacher workshops, and in my solar summer camp, we could easily count many sunspots-sometimes as many as 20 or more! Those were the days!

In the past two or three summers, however, it’s a lucky week to spot just a single sunspot! Most of the time, the Sun’s face has been a bland disk with few discernible surface features.

That status quo should start to change, now that we have allegedly reached solar minimum and are stepping onto the uphill slope toward the next maximum, which should happen sometime around 2011 or 2012. If you want to keep tabs on the rising solar activity, and you like lots of graphs and numbers and stuff like that, check out the Solar Cycle 24 website.

Oh, why is this Cycle 24? A 19^th Century astronomer who studied the then newly discovered sunspot cycle, Rudolf Wolf, established the cycle that spanned 1755 to 1766 as Cycle 1…and they’ve been counting up ever since.

But even in this “nap time” of the Sun, today’s modern solar observatories and spacecraft, with their arrays of high-tech cameras and sensors, see plenty on the Sun to keep them busy.

Japan’s Hinode spacecraft, launched in 2006, has returned libraries of amazing pictures and movies of solar flares, activity around sunspots, circulating hot gases, fine details of the life and times of magnetic fields…and all of this during solar minimum! I can’t wait until the Sun really gets going and Hinode becomes like a camera-happy tourist in Tahiti….

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.


Tags: Astronomy, chabot, cme, cycle 24, electromagnetic, galileo, hinode, KQED, kqedquest, magnetism, nasa, pbs, rudolf wolf, Science, solar flar, sun, sunspot, telescope



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Astronomy on the Wing

February 1st, 2008 by Ben Burress

More than meets the eye: The constellation Orion
in visible light (left) and infrared (right)
Visible light image: Akira Fujii;
Infrared image: Infrared Astronomical SatelliteSome months ago my blog, “SOFIA: Fly By Night,” talked about the up-and-coming astronomy ace of the night skies, SOFIA: the Stratospheric Observatory for Infrared Astronomy–a 2.5 meter infrared telescope built into a Boeing 747 airplane.

SOFIA’s been flying, and is gearing up to begin its first science flights in the not so distant future. SOFIA even put in an appearance in Bay Area skies a couple of weeks ago with a quick visit to NASA/Ames Research Center in Mountain View–then it was off again to its base of operations in the Mojave Desert.

Having worked on SOFIA’s predecessor, the Gerard P. Kuiper Airborne Observatory (KAO), in the last seven years of its operation, I thought I’d focus a bit on the science of airborne infrared astronomy, touching a bit on science done on the KAO over its 21-year career at NASA/Ames.

Why put a telescope on an airplane? Earth’s atmosphere, while transparent to the visible light the human eye can detect, is less so to many other wavelengths of light, including most infrared light. In fact, the water vapor in our atmosphere is pretty much opaque to a wide range of infrared wavelengths.

KAO flew at and altitude of 41,000 feet to get above as much as 99% of Earth’s atmospheric water vapor, giving astronomers a view of the infrared emissions from objects in space almost as if the telescope was out in space.

What’s so interesting about looking at infrared light? Aren’t visible light images taken from ground-based observatories enough?

Apparently not. Visible light is only a tiny fraction of the overall spectrum of electromagnetic radiation (the general term for “light” of all types–including gamma rays, X-rays, ultraviolet light, infrared light, microwaves and radio waves). There is a wealth of information contained in the entire electromagnetic spectrum that is only hinted at in the visible portion.

Visible light in our universe comes mostly from the photospheres of stars, either directly or by being reflected by objects such as dust, planets, comets, and the like; all of the light you see in the sky is starlight, either first hand or second hand.

Infrared light, however, is a lower energy form of electromagnetic radiation, and is emitted by any object or substance that is even slightly warm. So, interstellar clouds of molecules, rings of dust surrounding stars, atmospheres of planets–just about anything, in fact–emits its own infrared light, and observing the infrared emissions from these objects reveals a great deal about them: their chemical composition, their temperatures and densities, their velocities and structure–and a lot more.

One KAO astronomer observed the atmosphere of Venus to measure the relative abundance of hydrogen and deuterium (heavy hydrogen), looking for evidence of past oceans. Another observed Mars, looking for telltales of limestone (a mineral left behind by marine organisms) as evidence of past life on Mars. Others created detailed maps of clouds of complex molecules, probing the composition of the cooler material in our galaxy, as well as other galaxies.

The list goes on, as there’s plenty more cold matter in the universe than hot matter. Cooler matter can be more interesting, too, since complex molecules, like organic compounds and even life, don’t form in the sterile heat of stars.

So where KAO blazed an infrared contrail in the night skies, SOFIA may now follow and carry on the torch of astronomy, on the wing….
Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.



latitude: 37.8768, longitude: -122.251


Tags: chabot, KAO, KQED, kqedquest, nasa, photosphere, QUEST, Science, SOFIA, telescope



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Near Mars Object

January 16th, 2008 by Ben Burress

Victoria Crater on Mars, similar in size to the crater the
near-Mars asteroid 2007 WD 5 would have produced.
Credit: NASA/Mars Reconnaissance Orbiter

The possibility that a sizable asteroid would strike the planet Mars on January 30th temporarily raised the excitement level in the astronomical community to a pretty high level in the last couple of months. We were even toying with the idea of having a 3:00 AM Mars Bashing Party at Chabot that morning.

At one point astronomers had given odds of 1 in 25 that asteroid 2007 WD 5, newly discovered in November, would collide with Mars–which are astronomically great odds for this sort of thing. Alas, further observations refined our knowledge of the big rock’s trajectory, and the probability declined, hitting rock bottom (0.0%) by January 9th.

Why blog about a non-event? I see it as an opportunity to talk about big rocks bashing planets in general–specifically, the Earth.

While we haven’t witnessed an event like this one (a big impact on a solid, Earth-like planet), we have examined the remains of past events, on Earth as well as other planets and moons—such as the hole in the Arizona desert called “Meteor Crater,” an impact basin roughly the size of what might have been gouged out on Mars by 2007 WD 5. And compared to the asteroid that is believed to have caused the extinction of the dinosaurs, the Meteor Crater impact was a pipsqueak!

Smaller objects hit the Earth, or its atmosphere, all the time: meteors and meteorites. Fortunately we haven’t experienced a larger impact for a very long time. There was a significant impact of some kind in 1908, over Siberia–but luckily that wasn’t a major catastrophe.

Nevertheless, the possibility of a big impact on Earth is something to take seriously. NASA certainly does. They even have a program for it: the Near Earth Object Program, whose goal is to detect and track Near Earth Objects (NEOs) in order to warn of those that might eventually collide with the Earth. A NEO is defined as an asteroid or comet whose orbit carries it close to Earth. The program searches for NEOs that are 1 kilometer in size or larger–objects that would cause catastrophic local devastation and “severe global consequences.”

Thus far, over 5,000 NEOs have been found, almost 800 of them 1 kilometer across or larger–and it is expected that there are plenty more out there that we haven’t found.

So, is this a good idea? Do we really want to know that the end of the world is going to occur on such and such a date in the near future–or would it be better not to know, living our daily lives in blissful ignorance right up to the last, Earth-shattering day?

Well, whatever your philosophical approach to that question might be, there is a practical side to the NEO Program. If we can predict a NEO collision with enough advance warning, there may be something we can do to avert disaster. For example, we could send Bruce Willis out to destroy it… .

Seriously, though, NASA is working on methods of diverting the course of a NEO, possibly with a spaceship that acts as a sort of tug boat, gently nudging the NEO off course far enough in advance of the impact to make it eventually miss the Earth.

This month, however, Mars 1, asteroid 0. The Martians are quite relieved…

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.




latitude: 37.8768, longitude: -122.251


Tags: asteroid, KQED, kqedquest, mars, meteor, nasa, QUEST, Science, victoria crater



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Death Valley Nights

January 4th, 2008 by Ben Burress

There’s nothing like a trip away from the city lights to remind you just how bad light pollution can be here in the Bay Area.

The Milky Way in the skies of Death Valley’s
Devil’s Racetrack. Credit: Dan Duriscoe, U.S. National
Park ServiceI just got back from my semi-yearly pilgrimage to my favorite spot on Earth: Death Valley National Park. My main reasons for returning to this place again and again have mostly to do with hiking in the stunning natural beauty of the place, reconnecting with good times in my childhood, and reflecting spiritually on life, the Universe, and everything.

But, I can’t go to a place like that and not feel more connected with outer space. Not only is the night sky a celestial spectacle–but it’s darned cold there too, this time of year! Cold, like space. Each turn of the Earth through its own shadow is like a quick dip in the icy pool of space….

After twilight had faded, after the campfire had burned to embers–and as the frigid cold of the desert winter night started seeping through my layers of clothing–I lay down on the picnic bench and raised my binoculars to my eyes…

…and that’s all I had to do. Arcing overhead was the section of the Milky Way around the constellations Cassiopeia, Perseus, Andromeda, Pegasus–a section of the sky rich in a variety of “deep sky” objects (objects typically only visible through binoculars or telescopes).

There was the Double Cluster in Perseus–a pair of “open” clusters of stars.

Open clusters are stars bound together gravitationally, still clinging to each other after their “group infancy” in the gaseous cloud that gave birth to them. Stars in these clusters are young–and because of their youth, open clusters often contain a number of large, bright, blue stars that shine brilliantly–but which have short life spans as stars go, being more prolific hydrogen-burners (gas guzzlers). (In a word, you can’t find an old blue giant star.)

You can’t avoid seeing open clusters in this region; the place is positively littered with them….

This is also where the famous Andromeda Galaxy can be found, in the constellation Andromeda (where else?). What’s special about the Andromeda Galaxy? For one, it’s the closest large galaxy to our own, as well as the most distant object in the Universe that can be seen with the unaided human eye (without telescopic help). Looking at the Andromeda is like looking through a peephole into the realm beyond our Milky Way…

I could go on and on yakking about what I got to see in the clear, dark Death Valley skies last week, so I’ll have to stop myself now. Suffice to say that with a dark sky, a pair of binoculars, and a segment of the Milky Way in view, encountering the celestial wonders of the Universe in a very personal way is like shooting ducks in a barrel.

But don’t let the light polluted skies of the Bay Area stop you from trying it from your own backyard; there’s a lot to behold despite the city lights…

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.


Tags: chabot, death valley, KQED, kqedquest, light pollution, oakland, QUEST, Science



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