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Smithsonian’s annual Garden Fest will be held in the Enid A. Haupt Garden on Tuesday. Come learn about composting and worm farming! Photo by Kevin H., courtesy of Flickr Creative Commons

Friday, May 10: Garden Fest

How do you relate to the earth? In the garden outside of Smithsonian’s Castle, three African artists each recently completed a land art installation to explore issues of land use, environmental sustainability, hunger and humanity’s role on the planet. The installations are part of Earth Matters: Land as Material and Metaphor in the Arts of Africa, a new exhibition at the African Art Museum. Today, in celebration of the exhibition, Smithsonian’s annual Garden Fest will encourage families to consider their place on Earth, too, with art, composting, plant potting, worm farming and more. Role up your sleeves and get your hands dirty! Free. 11 a.m. to 7 p.m. Enid A. Haupt Garden.

Saturday, May 11: Super Science Saturday: Astronomy

Think you’re a space expert? Seen everything the Air and Space Museum has to offer? Then take a trip out to the Air and Space Museum’s Steven F. Udvar-Hazy Center near Dulles Airport, where thousands of aviation and space artifacts that take up too much room to be exhibited on the Mall are on display. On the second Saturday of each month (that’s today!), the museum holds demonstrations and hands-on activities that teach visitors about aviation and space exploration. Today’s theme should whet the space enthusiast’s appetite: Astronomy. Free. 10 a.m. to 3 p.m. Air and Space Museum Udvar-Hazy Center.

Sunday, May 12: Mendelssohn Piano Trio: Mother’s Day Tribute

Treat mom to some fantastic classical tunes this afternoon, courtesy of the Mendelssohn Piano Trio. The group—violinist Peter Sirotin, pianist Ya-Ting Chang and cellist Fiona Thompson—has played for audiences around the world for more than 15 years, and today will perform music by some of the best female composers. A question-and-answer session will follow the performance. Free tickets available in the G Street lobby beginning 30 minutes before the performance. 3 p.m. to 4:30 pm. American Art Museum.

Also, check out our Visitors Guide App. Get the most out of your trip to Washington, D.C. and the National Mall with this selection of custom-built tours, based on your available time and passions. From the editors of Smithsonian magazine, the app is packed with handy navigational tools, maps, museum floor plans and museum information including ‘Greatest Hits’ for each Smithsonian museum.

For a complete listing of Smithsonian events and exhibitions visit the goSmithsonian Visitors Guide. Additional reporting by Michelle Strange.

A habitable planet orbits a white dwarf. Here the ghostly blue ring is a planetary nebula—hydrogen gas the star ejected as it evolved from a red giant to a white dwarf. Illustration by David A. Aguilar (CfA)

According to a new proposal from astronomers and professors Avi Loeb and Dan Maoz, signs of life may be awaiting detection in the shadows of death. Looking to the abundance of dying stars known as white dwarfs, Loeb and Maoz devised a simple way to search for oxygen in the atmosphere of exoplanets which orbit around white dwarfs much the way Earth orbits the sun. Loeb says the theory could yield results within the decade with the launch of NASA’s James Webb Telescope in 2018.

The pair published a paper in February, ”Detecting bio-markers in habitable-zone earths transiting white dwarfs,” outlining their theoretical research. In it, Loeb, chair of Harvard University’s department of Astronomy and director of the Institute for Theory and Computation (ITC) within the Harvard-Smithsonian Center for Astrophysics, explains that though a white dwarf is simply the cooling core of a dead star, its radiant heat and light can host life on orbiting planets for billions of years.

“We know of a few thousand of those planets by now and there must be many more out there. And a key question is, if a planet is quite similar to Earth in terms of its rocky material; and if it’s the right distance from the furnace, the central star that keeps it warm so that adequate water can exist on its surface; would the chemistry of life naturally arise, and would life exist the same way it does on Earth?” Loeb says it’s a difficult question to address with theory alone. “The best way to approach it,” he says, “would be to try and observe other planets, and search for indications of life.” And that rather than visiting those places, Loeb recommends searching “for signatures of molecules that are naturally produced by life and the most generic one is oxygen.”

Recent research suggests not only that there are plenty of exoplanets out there like our own, but that they are often paired with and orbiting white dwarfs. According to Loeb, “Somewhere between 15 to 30 percent of [white dwarfs] show evidence of rocky material on their surface, and such material would not be there unless there was rocky stuff around them,” meaning that these are the exoplanets that could potentially sustain life.

Signs of extraterrestrial life could be hiding in the shadow of dying white dwarf stars. Image courtesy of NASA and H. Richer (University of British Columbia)

With this in mind, Loeb and Maoz postulated that researchers could find oxygen by measuring the atmospheric transmission spectrum of these planets as it passes in front of a white dwarf. Unfortunately, the pair will have to wait until 2018, when the launch of the James Webb Telescope is scheduled. The measurements have to be taken outside the Earth’s atmosphere, where oxygen concentrations can alter the incoming light.

In the meantime, Loeb plans to use the results of an upcoming survey of stars to identify prime candidates for the space telescope to measure. “One can follow up on the sample of white dwarfs that is found by this survey and search for examples of where we see evidence of a planet transiting a white dwarf and, if it’s the right distance, that would be a very good candidate for JWST to look at.”

The researchers estimate that a sample size of some 500 white dwarfs will be needed, to account for a variety of alignments between planets and their stars, but he’s optimistic about the potential to find something.

“I think if we have the technology, we should do it,” he says. “There are several examples in the history of astronomy where people hesitated.” Most recently, he says, researchers were not given observation time to search for exoplanets. “Even though it was feasible technologically, they said no we won’t give the time for that because it’s speculative and the chance is very small that there would be a Jupiter close to a star.” Of course, “only a decade later these Jupiters were found by chance, and it opened completely this field of exoplanets.”

Loeb, who sprinkles his lectures with talk of religion and philosophy, says the lesson is to remain open-minded. “The way to make discoveries is not to have a prejudice and just to explore the universe because our imagination is quite limited.”

In the end, Loeb says his proposal is actually simple, a hallmark of his approach to physics that has earned him a Chambliss Astronomical Writing Award from the American Astronomical Society for his book, “How Did the First Stars and Galaxies Form?“

Today, at around 9:20 a.m. local time in Chelyabinsk, Russia, a massive 11-ton meteor burned up in the sky, triggering a sonic boom that damaged buildings and shattered windows in six cities and reportedly injured hundreds. Eyewitnesses say the meteor’s shockingly bright flash as it burned up (10 seconds into the Russia Today video above) was briefly brighter than the morning sun.

That this event happened today—the same day a 147-foot wide asteroid will whiz extremely close to the Earth at 2:26 p.m. EST—seems to be a coincidence of astronomical proportions, as experts say the two events are entirely unrelated. But unlike the asteroid, which will cause no physical damage, the meteor’s sonic boom as it entered the atmosphere, fractured roughly 18 to 32 miles above the ground and subsequently rained fragments over the region, led to as many as 900 injuries, 31 hospitalizations and widespread damage including the collapse of a rooftop at a zinc factory .

So, what caused this massive explosion? “For one, meteors move extremely fast—faster than the speed of sound—so there’s a ton of friction being generated as it comes through the atmosphere,” says Cari Corrigan, a geologist with the Natural History Museum who specializes in meteors. “If there are any weaknesses in it already, or if there is ice that melts and leaves empty fractures—like freezing and thawing in a pothole—it could easily explode.”

To get a knotty bit of nomenclature out of the way, meteor refers to a variety of pieces of debris—made up of either rock, metal, or a mix of the two—that enter the atmosphere from outer space. Before doing so, they’re called meteoroids. Most burn up entirely during their descent, but if any intact fragments do make it to the ground, they’re called meteorites. Meteors are also called “shooting stars” because of the heat and light produced when they slam into the still atmosphere at supersonic speeds—today’s meteor was estimated to be traveling faster than 33,000 m.p.h.

The distinction between this meteor and the asteroid that will fly past us later today, according to Corrigan, is a matter of size and origin. “Asteroids are generally bigger, and they typically come from the asteroid belt, between Mars and Jupiter,” she says. The size difference also explains why we were able to predict the arrival of the asteroid nearly a year ago, but this meteor caught us by surprise: It’s impossible to spot the smaller meteoroids up in space with our telescopes.

Meteors like the one that fell today aren’t exceedingly rare, but for one to cause this much damage is almost unheard of. “There are events like this in recorded history, but this is likely the first time it’s happened over such a populated area and this level of destruction has been documented,” Corrigan says. Notable meteors in recorded history include the Tunguska event (a 1908 explosion over a remote area in Russia that knocked down more than 80 million trees covering an area of some 830-square miles), the Benld meteorite (a small object that landed in Illinois in 1938 that punctured the roof of a car) and the Carancas impact (a 2007 meteorite that crashed in a Peruvian village and may have caused groundwater contamination).

In 1938, a meteorite fell over Benld, Illinois, puncturing the roof of a car, become embedded in the backseat. Image via Wikimedia Commons/Shsilver

Much larger meteorites have fallen in prehistory and been discovered much later, including the Willamette Meteorite, a 32,000-pound hunk of iron that fell millennia ago and was transported to Oregon during the last ice age. The largest meteorite ever discovered in North America, it is now part of the collections of the Natural History Museum.

The Willamette Meteorite is on view at the Natural History Museum. Image via Wikimedia Commons/Dante Alighieri

Early reports suggest that remnants of the meteor have fallen into a reservoir near the town of Chebarkul; testing on these meteorite fragments could provide more information on the object’s composition and origin. “It might be an ordinary chondrite—which is  what 90 percent of the meteorites that we have are made of—or it could be something more rare,” Corrigan says.

While chondrites are made mostly of stone and result from the relatively recent breakup of asteroids, iron meteorites originate from the cores of more ancient asteroids, and even rarer types come from debris broken off from the moon or Mars. ”Every meteorite that we get is another piece of the puzzle,” says Corrigan. “They’re clues towards how the solar system and Earth were formed.”

Hi-C captured the most detailed images of the sun’s corona in July 2012. Courtesy of NASA

When the band They Might Be Giants re-recorded the 1959 song “Why Does the Sun Shine?” for its 1993 EP, they played to a much-repeated piece of science fiction. The track, subtitled “The Sun is a Mass of Incandescent Gas,” gets some basic sun science wrong.  “A gas is a state of matter in which the material is not ionized, so all of the atoms still have all of their electrons and really the sun’s gas is in a state called plasma,” says Smithsonian astrophysicist Mark Weber.

Though scientists had known this for quite some time, once it was pointed out to the band, it promptly issued an updated track in 2009, “Why Does the Sun Really Shine? The Sun is a Miasma of Incandescent Plasma.”

But Weber, who will present Saturday, November 17 at the Air and Space Museum, says, that’s not all that’s new in the world of sun science.

“The sun is a very interesting object of study,” he says. “People shouldn’t assume that we’ve moved on from the sun.”

The sun does all kinds of things, Weber says, “it has all sorts of different features and all sorts of different events and phenomenologies.”

One of the phenomena currently on the minds of solar researchers is why the corona, the plasma atmosphere surrounding the surface of the sun, is so incredibly hot. “All of the energy from the sun comes from the interior of the sun and so sort of a simple, thermodynamic interpretation would expect the temperature of the sun to decrease as you go further and further away from the core,” says Weber. And that’s mostly true, he says, with one notable exception: “There’s a point we call the transition region, where the temperature rockets from a few thousand degrees at the surface of the sun up to millions of degrees in the corona.”

Weber’s particular focus is determining precisely how hot the corona is. Scientists are also trying to understand what processes might be heating the plasma to such extremes. Weber says, “There’s a lots of great ideas, it’s not that we don’t have any idea what’s going on,” adding, “What might be heating one part of the corona, like say a single standing loop of plasma, might be very different from what’s going on, say, in an active region, which are these areas over sun spots that are really hot and have all kinds of eruptions happening all the time.”

Between the transition region and the erupting sun spots, Weber seeks to show people that the sun is anything but static. “A lot of people have this idea that the sun is a yellow ball in the sky and that we understand everything about it.” But he says the sun is incredibly dynamic and has been dazzling scientists for hundreds of years. In fact, in the 19th century, scientists believed they had discovered completely new elements while studying the spectral emissions from the sun.  “They were seeing spectral lines that they couldn’t identify,” says Weber. “That’s because these lines are coming from very highly ionized ions, which implies a very high temperature.” But at the time, says Weber, “No one expected that the temperature of the atmosphere of the sun was so much hotter, that just didn’t occur to people.” And so they named the new element–which was actually highly ionized iron–coronium.

Comparing older, less detailed images of the corona with Hi-C’s newer, more detailed images, researchers were able to see more than ever before. Courtesy of NASA

Now of course, scientists are capable of collecting far more sophisticated analysis, including from a recent rocket mission called the High Resolution Coronal Imager, or Hi-C. “We got to see a small section of the solar atmosphere at a higher resolution than anyone had ever observed before,” says Weber, who was involved in the project. One of the things they were finally able to see was that what had once been thought to be single loops of plasma were in fact multiple intricately braided strands. Weber says, “We could even see the braiding sort of twisting around and shifting, as we were watching the sun with this rocket flight.”

With all the new imaging available, Weber says people are amazed to discover how beautiful the sun truly is. He says, “You’re just sort of overwhelmed by how much is going on.” And, he adds, “It’s a fascinating area to do physics in!”

As part of the Smithsonian’s Stars Lecture Series, Mark Weber will present his lecture, The Dynamic Sun at the Air and Space Museum, Saturday, November 17 at starting at 5:15 p.m.

In association with the new exhibition, “African Cosmos: Stellar Arts," the African Art Museum hosts a talk by astronomist-artist Karel Nel this week. Image courtesy of the African Art Museum.

Tuesday, June 19 The Art of Political Advertising

From 30-second spots to 30-minute infomercials, presidential campaigns have long relied on television as the best way to communicate with the American public. Trace the genre’s evolution from early ads to the state of today’s industry with Robert Mann, author of Daisy Petals and Mushroom Clouds: LBJ, Barry Goldwater, and the Ad That Changed American Politics, and political consultant Mark Putnam, who wrote and produced Barack Obama’s 2008 30-minute TV special American Stories, American Solutions. Stick around afterwards for a moderated discussion led by Alicia Kolar Prevost of American University’s Campaign Management. $35 for general admission, $30 for members. 6:30 p.m. to 8:30 p.m. S. Dillon Ripley Center.

Wednesday, June 20 Luce Design with Jackie Flanagan

DC fashion designer Jackie Flanagan kicks off the American Art Museum’s new summer series showcasing local designers. Flanagan, who owns the DC boutique Nana, will talk about her design process, her desire to create ethically-made clothing, her support of other local designers, and how she is inspired by color and vintage and modern designs. Free. 5:30 p.m. to 7:00 p.m. Luce Foundation Center, American Art Museum.

Thursday, June 21 Karel Nel

Star-gazing will never be the same after this talk by South African artist Karel Nel, who explores the intersection of arts, spirituality and astronomy. In 2004, Nel became an artist in residence for COSMOS, an astronomy project that is mapping a two-degree square area of the sky. Joining the conversation is Nick Scoville, the principal investigator of the Hubble Space Telescope imaging of COSMOS. Free. 6:00 p.m. to 7:30 p.m. African Art Museum.

For a complete listing of Smithsonian events and exhibitions visit the goSmithsonian Visitors Guide. Additional reporting by Michelle Strange.