Smithsonian.com

Amazon rainforest deforestation, courtesy of Flickr user Threat_to_Democracy

Here’s a roundup of the best of what I’ve been reading in the past couple of weeks:

Are global warming and deforestation too scary for Sesame Street?: A couple of years ago Sesame Workshop named these as adult topics too scary for young children. Instead they focus on teaching kids to respect the Earth. Climate change and deforestation are scary, and I’m okay with keeping them away from five-year-olds. Am I wrong?

One Giant Leap seen again: Bad Astronomer Phil Plait has images from the Lunar Reconnaissance Orbiter of the Apollo 11 landing site. You can even see the lunar lander footpads.

Pigs Prove to Be Smart, if Not Vain: Pigs successfully pass the mirror self-recognition test, a sign of cognition. But if pigs are smarter than we think, will we still eat them? (No bacon would be a bad thing.)

An Epidemic of Fear: How Panicked Parents Skipping Shots Endangers Us All: This is the article that inspired my Vaccine Week last month. You may have also seen Does the Vaccine Matter? in The Atlantic. I left that one out because, despite the headline on the cover, it’s not about swine flu—it’s about whether or not vaccinating the elderly against the seasonal flu saves any lives. An interesting question, but that story misses the boat, as was pointed out on Respectful Insolence.

What Ever Happened to the Amazon Rain Forest?: Brenden Borrell (author of great Smithsonian stories on chilis and cassowaries) tackles the issue of whether or not the Amazon rain forest has been saved. Short answer—not yet.

Jack White: Carl Sagan’s biggest fan: That’s Jack White of the White Stripes. And newest member of the Planetary Society.

And though I had been looking forward to reading Superfreakonomics (having been a fan of Freakonomics), I’ve decided to skip it. I’ve now read several essays critical of their climate change chapter, but it’s the open letter on Real Climate from geophysicist Raymond T. Pierrehumbert that has convinced me that the Freakonomics team desperately needs a fact checker. I’d offer my services, but Smithsonian keeps me pretty busy.

You may recognize Felicia Day as Dr. Horrible’s red-haired obsession (or maybe from that appliance commercial). And if you’ve been reading this blog, you probably have heard of NASA’s Spitzer Space Telescope, which was responsible for last month’s discovery of a massive ring around Saturn. Add the two together and you get the latest video about colliding galaxies from IRrelevant astronomy. If you find this one funny, and if you are geeky enough to recognize names like Sean Astin and George Takei, you’ll probably spend the rest of the day giggling as you watch earlier episodes from the series. They can be found intermingled with more traditional educational videos on the telescope’s YouTube site. Enjoy!

The Abbé Nicolas-Louis de Lacaille was the first to find this cluster of stars, in 1751 while on an astronomical expedition to the Cape of Good Hope (South Africa). The Kappa Crucis Cluster (NGC 4755), which resides near the Southern Cross, received the nickname the “Jewel Box” during the next century, when astronomer John Herschel viewed it through his telescope and saw the stars were different colors—pale blue and orange. He wrote: “The stars which compose it, seen in a telescope of diameter large enough to enable the colours to be distinguished, have the effect of a casket of variously coloured precious stones.”

We now know that the cluster is about 6,400 light-years away from Earth and around 16 million years old. The stars in the Jewel Box all formed from the same cloud of dust and gas, are about the same age and have similar chemical compositions. The image above was taken recently with MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile. Scientists use clusters like this one to study the evolution of stars. (Image credit: ESO. Click here to find additional images of the cluster, including one from the Hubble Space Telescope.)

Check out the entire collection of Pictures of the Week on our Facebook fan page.

Look to Orion tomorrow morning to see the meteor shower (illustration courtesy stardate.org)

Right now, the Earth is traveling through a trail left behind by Halley’s comet, which last passed through our neighborhood in 1986 (it will return in 2061). These little bits of debris produce a yearly meteor shower, the Orionids, named so because they appear to originate in the constellation Orion.

The best time to see this little light show—around 15 to 20 green and yellow meteors each hour during peak in the Northern Hemisphere—is tomorrow morning before dawn when the crescent moon is below the horizon and its light cannot overpower the streaky meteors. Observers in the Southern Hemisphere will get an even better show, according to meteorshowersonline.com.

The discovery of the Orionid meteor shower should be credited to E. C. Herrick (Connecticut, USA). In 1839, he made the ambiguous statement that activity seemed to be present during October 8 to 15. A similar statement was made in 1840, when he commented that the “precise date of the greatest meteoric frequency in October is still less definitely known, but it will in all probability be found to occur between the 8th and 25th of the month.”

The first precise observation of this shower was made by A. S. Herschel on 1864 October 18, when fourteen meteors were found to radiate from the constellation of Orion. Herschel confirmed that a shower originated from Orion on 1865 October 20. Thereafter, interest in this stream increased very rapidly—with the Orionids becoming one of best observed annual showers.

StarDate Online recommends going to a city or state park, away from the lights, and lying down to get the best view of the sky. “If you can see all of the stars in the Little Dipper, you have good dark-adapted vision.” And if it’s cloudy where you live, you can’t get to a dark enough spot or you oversleep, don’t worry–you’ve got a few more chances to view a meteor shower in the coming months:

Leonids
Parent comet: 55P/Tempel-Tuttle
Dates: November 17 (night) and 18 (morning)

Geminids
Parent: 3200 Phaeton
Dates: December 13 and 14

Quatrantids
Parent comet: 2003 EH1
Dates: January 3 and 4

NASA’s Spitzer Space Telescope has discovered a new ring around Saturn.  This ring is very different from those previously known. In some ways, this ring resembles the “accretionary disk” found around some stars more than it resembles the thin, orderly rings that Saturn is famous for.

The new ring is much larger than any of the planet’s other rings and is tilted about 27 degrees off the main plane of rings. It starts about six million kilometers out from the planet, and is about 12 million kilometers wide. The moon Phoebe orbits just within this ring and is tentatively thought to be responsible for the ring’s existence. It would appear that as Phoebe circles around Saturn, it occasionally collides with comets, which are obliterated, with the debris from the collision contributing to the ring.

This ring is different from the other rings not only in its angle, but also in its thickness. The better known Saturnian rings are very thin (about 10 meters thick), but this mega-ring measures about 2.5 million kilometers thick. That is roughly 20 times the diameter of Saturn. As Anne Verbiscer, one of the authors of the study reporting this feature, puts it, “This is one supersized ring. If you could see the ring [from Earth], it would span the width of two full moons’ worth of sky, one on either side of Saturn.”

An artist’s conception of the ring as it would appear if you had infrared detecting eyes. Saturn is the tiny dot in the middle as indicated. (Image credit: NASA/JPL-Caltech/Keck)

The ring appears to be made out of very dispersed particles of ice and dust, which were visible to the Spitzer telescope using its infrared detectors. The particles are spread out so thinly that if you were in the thickest part in a spacecraft, you would not easily detect the ring’s existence. The Spitzer instruments were able to “see” the ring only because they were very sensitive to even tiny amounts of infrared radiation emanating from the particles making up the ring.

The discovery helps solve a mystery regarding the Saturnian moon Iapetus. Iapetus has an odd appearance whereby one side is bright and the other is really dark, in a pattern resembling a yin-yang symbol. The dark area is called the Cassini Regio, after Giovanni Cassini who discovered Iapetus in 1671 and later described its dark side.

Photograph of Iapetus taken by the Cassini spacecraft. (Image credit: NASA/JPL/Space Science Institute)

Iapetus, the previously known rings of Saturn and most of Saturn’s moons circle in one direction, while the newly discovered mega ring circles the other way. It appears that the material from this ring splatters Iapetus—think of bugs hitting a windshield—as the moon and the ring move in opposite directions.

For more information, see NASA’s Spitzer Space Telescope web site.

The lunar south pole as it will appear on the night of impact. Photo Credit - NMSU / MSFC Tortugas Observatory.

On Friday, October 9, two space ships will crash into the moon, and you will be able to see it happen.

All you need to do is find the crater Cabeus, which is near the Moon’s south pole. Be watching at 11:30 UT (That’s 4:30 a.m. Pacific Time, 6:30 a.m. Central.) Bring your telescope. It should be a pretty good telescope. According to NASA:

“We expect the debris plumes to be visible through mid-sized backyard telescopes 10 inches and larger,” says Brian Day of NASA/Ames. Day is an amateur astronomer and the Education and Public Outreach Lead for LCROSS. “The initial explosions will probably be hidden behind crater walls, but the plumes will rise high enough above the crater’s rim to be seen from Earth.”

If you live in the eastern part of the United States or anywhere towards daylight (east) from there, it may be too bright. Hawaii is ideal within the US, but anywhere west of the Mississippi is a potential viewing spot. I live four blocks east of the Mississippi, so I guess I’ll have to drag my telescope down to the shore and canoe across for better viewing!

There is another way to see the impacts: Tune in NASA TV. Coverage starts at 3:15 a.m. PDT. In some areas, you may get that station on your local cable system.

But why are the spaceships crashing into the Moon? Has something gone terribly wrong? Are we being invaded by aliens?

Well, this is an experiment cooked up by NASA to see if there is water on the Moon. First, a rocket called The Centaur will hit the moon. This rocket weighs about 2,200 kg and it is going fast, so there will be a great deal of energy released. A huge plume of debris will be blown up as much as 10 kilometers. This plume will be observed from earth, the Hubble space telescope, and the Lunar Reconnaissance Orbiter (LRO), and analyzed for presence of water.

However, close behind The Centaur will be the LCROSS space ship. This craft has instrumentation on it that will allow a much more detailed analysis of the plume. LCROSS will fly into the plume sent up by The Centaur, analyze the material really fast, and send its data back to earth. And then … it will also crash into the moon.

“If there’s water there, or anything else interesting, we’ll find it,” says Tony Colaprete of NASA Ames, the mission’s principal investigator.

LCROSS will hit the moon about four minutes after The Centaur. The most interesting statement in NASA’s press release regarding this experiment is probably this one:

“Remember, we’ve never done this before. We’re not 100% sure what will happen, and big surprises are possible.”

If you are interested in viewing this spectacular lunar experiment at a public event (and the public events are quite diverse as to what they offer, see if there is one in your area and refer to the LCROSS Viewer’s Guide.

Greg Laden is guest-blogging this week while Sarah is on vacation. You can find his regular blog at Scienceblogs.com and Quiche Moraine.

You may know that much of the climate change on earth over the last two million years–the coming and going of ice ages–is caused by the “orbital geometry” of the planet. The amount of planetary tilt and the time of year the tilt occurs change over time. When the Northern Hemisphere is less tilted towards the sun on June 21st, and at the same time the Earth is as far from the sun in its elliptical orbit as it ever gets, ice age conditions prevail. This makes ice ages on Earth pretty regular, cyclic, events.

You also may know that a big chunk of Earth’s water is frozen into the ice caps.

You also may know that the history of Earth climate is preserved, in part, in changes in the ice in those ice caps.

Well, same for Mars!

Images from the Shallow Radar instrument on NASA's Mars Reconnaissance Orbiter. Pane "a" is a "radargram" cross section, showing distinct layers.

Previously developed climate models suggested that the last 300,000 years of Martian history experienced low-level swings in climate, while the prior 600,000 years experienced more severe swings, owing to differences in the tilt of the planet. Most of the water we know about on Mars is in the Martian polar caps. And now, we can see, using radar, evidence of climate change reflected in that ice. From NASA:

New, three-dimensional imaging of Martian north-polar ice layers by a radar instrument on NASA’s Mars Reconnaissance Orbiter is consistent with theoretical models of Martian climate swings during the past few million years.

Alignment of the layering patterns with the modeled climate cycles provides insight about how the layers accumulated. These ice-rich, layered deposits cover an area one-third larger than Texas and form a stack up to 2 kilometers (1.2 miles) thick atop a basal deposit with additional ice.

“Contrast in electrical properties between layers is what provides the reflectivity we observe with the radar,” said Nathaniel Putzig…, a member of the science team for the Shallow Radar instrument on the orbiter. “The pattern of reflectivity tells us about the pattern of material variations within the layers.”

Essentially, the radar detects different amounts and/or kinds of dirt, and the ice is dirty in different ways. These vastly different climate periods (of more vs. less severe oscillation in climate change) probably leave behind different amounts of dirt in the ice. The radar can penetrate the ice and “see” these differences, with one period having more dirt than another.

There are two distinct models for how the dirt gets concentrated in the ice enough to be distinguished by the radar. One is that ice evaporates away more during some periods than others, leaving behind more dirt when the ice disappears, like the dirty snow during the late winter in northern cities. The other model simply has more dust in the atmosphere, and thus more dust falling on the ice, during certain periods. The present study supports the later model (more dust = dirtier ice). The radar reflectivity signal observed in this study is probably too coarse to link specific features of the signals with specific Martian “ice ages” so far.

“The radar has been giving us spectacular results,” said Jeffrey Plaut of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., a co-author of the paper. “We have mapped continuous underground layers in three dimensions across a vast area.”

Read more about this study.

The other images are different views of the polar cap using the radar images, and are explained in great detail on NASA’s site.

Comet Shoemaker-Levy 9 broke into pieces before hiting Jupiter in 1994. The dark spots mark the impact sites. (Credit: Hubble Space Telescope Comet Team and NASA)

How many moons does Jupiter have? The answer may not be as simple as it sounds. Jupiter, the largest planet in our solar system, is so big that it can deflect the paths of comets and other objects, some of which might otherwise hit the Earth. Some of those comets hit the surface of the gas giant. Others, though, may circle Jupiter for years as temporary moons before continuing on their way through the solar system or meeting their end on the planet’s surface.

The most famous object to impact Jupiter is probably Comet Shoemaker-Levy 9, which crashed down in 1994. However, the comet first circled the planet as a temporary moon, trapped by Jupiter’s gravitational pull. And it isn’t the only one.

Astronomers from Japan and Northern Ireland, presenting their findings today at the European Planetary Science Congress, used observations of Comet Kushida-Muramatsu—from when it was discovered in 1993 and when it returned in 2001—to calculate the comet’s path over the previous century. They determined that the comet became a temporary moon when it entered Jupiter’s neighborhood in 1949. It made two full, if irregular, orbits around the planet, and then continued its travels into the inner solar system in 1962.

The researchers also predict that Comet 111P/Helin-Roman-Crockett, which circled Jupiter between 1967 and 1985, will again become a temporary moon and complete six loops around the planet between 2068 and 2086.

“The results of our study suggests that impacts on Jupiter and temporary satellite capture events may happen more frequently than we previously expected,” David Asher of Northern Ireland’s Armagh Observatory told the AFP.

So how many moons does Jupiter have? Depends on when you ask.