May 28, 2013
Gaze at the stars this evening and you will see a rare phenomenon: three planets, all glowing so close to each other that it looks like they might bump. The trio—Venus, Jupiter and Mercury—actually are millions of miles apart, but on this special occasion their orbits are aligned with ours such that they appear side by side.
The Milky Way is home to an estimated 200 billion to 400 billion stars, and as many as 17 billion planets. Amazing things are happening around the cosmos every minute, but it is a treat when we can catch an unusual celestial event just by looking up, without even a telescope.
Tonight and in the coming months, a few of these events will be visible to the naked eye from any backyard in the United States so long as the sky is free of clouds. Be sure to mark your calendars—the events are fleeting, and occur at most once a year.
To make sense of these celestial happenings, we enlisted the help of Kimberly Arcand and Megan Watzke, authors of Your Ticket to the Universe: A Guide to Exploring the Cosmos, recently published by Smithsonian Books. Arcand and Watzke both work as communications officers for NASA’s Chandra X-ray Observatory, which means they have extensive experience dealing with the cosmos and capturing arresting astronomical images. The two have collaborated before on From Earth to the Universe and From Earth to the Solar System, two projects that bring the universe’s wonders down to earth in breathtaking photographs. Their new book features 240 full-color images from telescopes, observatories and in-space cameras, including the Hubble and Spitzer Space Telescopes and NASA’s Curiosity rover.
“You don’t need a medical degree to know when you’re sick or a doctorate in literature to appreciate a novel,” Arcand and Watzke write. “In the same spirit, even those of us who do not have advanced degrees in astronomy, astrophysics or space science can gain access to all the wonder and experience that the Universe has to offer.”
If this list whets your appetite for more exciting cosmological happenings, check out the book to learn far more amazing facts about the Universe, and peruse some of these lists of even more celestial events taking place this year.
Tuesday, May 28: Conjunction of Venus, Jupiter and Mercury
In celestial terms, “conjunctions” are when two or more objects appear really close together in the sky. On this rare night, Venus and Jupiter will come within 1 degree of each other, and Mercury, which has been close to the pair since Friday, will be within 5 degrees of them. According to NASA, the last time triple conjunction occurred in 2011, and another. won’t be seen until October 2015.
The three planets will be most visible 45 minutes to an hour after sunset. In the twilight, look west-northwest and low in the sky. Venus is the brightest of the three planets, and Jupiter will be close above it to the right.
Arcand and Watzke say:
Planets are always fun objects to try to find in the night sky. Because they are closer to us than the stars (other than the Sun, of course), they appear as tiny solid disks rather the just pinpricks of light. This means that the planets appear to be less affected by the blurring effects of our atmosphere, which is what causes the stars to “twinkle.” (But stars don’t actually twinkle. The movements of air and moisture in the Earth’s atmosphere makes the distant light look like it’s changing in ways that it is not.)
Venus and Jupiter are not actually any nearer each other than normal–they just appear to align from our vantage point on Earth. Venus is still closer to the Sun than the Earth, and Jupiter remains in its orbit as the fifth planet out at an average of about 500 million miles from the center of the Solar System.
Fun fact: Venus is often a great night sky viewing target and was long referred to as “the evening star” because of it’s clear and early appearance in the evening. So we’re often wishing on a planet and not a star if we wish up on the first bright light of the evening.
The biggest full moon of 2013! On Sunday at 7 a.m. GMT (that’s 3 a.m. in New York, midnight in Los Angeles), the moon will reach it’s closest point to earth of the year, a mere 221,824 miles away. That’s not quite close enough to touch, but it may look like it is.
Arcand and Watzke say:
As the Moon travels in its orbit around Earth, more or less of the Moon’s disk is illuminated by the Sun. When the Moon is behind the Earth with respect to the Sun, we can see its full face lit up by sunlight. This is what we know as the “full Moon,” and it occurs once every 27 days or so. Use the opportunity of a fully illuminated Moon—especially this big one—to get a really good look at our nearest neighbor in space. The pockmarks are the result of meteors that have struck the lunar surface. Because the Moon has essentially no atmosphere or weather like we do on Earth, these craters have been preserved in pristine condition instead of being erased like those on Earth largely have.
Fun fact: On the occasional times a full moon happens 13 times in a year, instead of 12, the last full moon is called a “Blue Moon”, which is where the phrase comes from.
Two major annual meteor showers, the Delta Aquarid and the Perseid, will be shooting across the night sky throughout most of July and August.
The Delta Aquarid Meteor Shower runs from July 12 to August 23, and peaks from July 27 to 28 with up to 20 meteors per hour. It comes from the debris of comets Marsden and Kracht. It is not highly visible in America, and best seen from the Southern Hemisphere and at low altitudes just north of the equator. Light from the moon, in its second quarter, will block most of the faint meteors from sight, too, but you should still be able to see at least some of the big ones if you’re on the lookout for them.
The Perseid Meteor Shower runs from July 17 to August 24, and peaks from August 11 to 12 with up to 60 meteors per hour. It is produced by comet Swift-Tuttle. Unlike the Delta Aquarid, it is highly visible in the Northern Hemisphere, and peaks during a first quarter moon, which means hardly any light will obstruct the show.
Arcand and Watzke say:
Meteor showers are great to plan summer evenings around. These showers happen when the Earth passes through a cloud of rocks from a comet that has been ripped apart by gravity. While many people want to use binoculars or telescopes in order to get the best views of events in the night sky, meteor showers are actually best viewed with just your eyes. That’s because binoculars or a telescope will limit your field of view. The game in watching meteor showers is to get the widest and darkest view of the night sky.
Fun fact: Despite their nickname of “shooting stars” in popular culture, these are not stars at all. Impress your friends and family by pointing out that these streaks of light are, in fact, pieces of rock and other debris whizzing through the Earth’s atmosphere.
November 16, 2012
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.
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.
October 4, 2012
Friday, October 5 Mrs. Judo
At 99 years old, judo master Keiko Fukuda still keeps a busy schedule, teaching three times a week at her San Francisco dojo. Fukuda holds the highest ranking possible in judo and is the last living student of the sport’s founder, Kanō Jigorō. The new documentary Mrs. Judo: Be Strong, Be Gentle, Be Beautiful tells Fukuda’s unique story. The film explores the roots of judo while also chronicling the life of this living legend. The screening is preceded by Two Seconds after Laughter. Free. 7 p.m. Freer Gallery.
No one ever told Peter Cheimets not to stare at the sun. Or if someone did, he definitely didn’t listen. The senior project engineer at the Smithsonian Astrophysical Observatory spends his days working at the cutting edge of solar observation. This year, after 30 years of development, special telescopes capable of observing the sun were finally perfected. Ushering in a new era of observation, Cheimets will discuss what made this moment possible and some of the early results from his research. Free, but tickets are required. Tickets available 10 a.m. to 5:30 p.m. at the IMAX Theater Box Offices. 5:15 p.m. to 6:45 p.m. Air and Space Museum. For more information, call 202-633-2398 or e-mail email@example.com.
Sunday, October 7 Masterworks of Three Centuries 2012-2013 Concert Series
The Smithsonian Associates celebrates the Smithsonian Chamber Music Society’s 36th season. Though the event promises to be an eclectic mix of classics and lesser-known works, don’t be intimidated. The Chamber Music Society’s artistic director, Kenneth Slowik, will give a pre-concert talk that digs into the music on tap and explores the biographies behind the featured composers, including Beethoven, Faure and Chausson. It’s the perfect start to a new season. $28 general admission, $22 members. Purchase tickets here. 6:30 p.m. to 9:30 p.m. American History Museum, Hall of Musical Instruments.
March 30, 2012
In 2005, Warren Brown of the Smithsonian Astrophysical Observatory noticed something rather unusual in the sky: a star traveling out of the Milky Way galaxy at roughly 1.5 million miles per hour. The strange discovery could only be explained by an even stranger prediction, made nearly two decades earlier by an astronomer named J.G. Hills.
“He predicted that if you have two stars orbiting each other—a so-called binary system—and they get too close to the central black hole in the Milky Way, they will get ripped apart,” says SAO astrophysicist Avi Loeb. “One of the stars will go into a tighter orbit around the black hole, and the second one will be flung out of the galaxy.”
Since Brown’s 2005 discovery, at least 21 hypervelocity stars (as they’ve come to be called) have been observed speeding out of our galaxy. But only recently did anyone look to see if there might be hypervelocity planets, as well. “My collaborator Idan Ginsburg and I did some work on hypervelocity stars, and at some point, I was talking with him about perhaps looking into planets,” Loeb says. “One day, at lunch, it clicked: we could actually write a paper on them, because there is a method of finding them.”
Loeb had realized that a planet orbiting one of these hypervelocity stars could be observed by what’s called the transit method: when a distant planet crosses between its star and our telescope, the light of the star dims slightly, indicating the presence of the planet. First, though, he and Ginsburg had to determine whether these planets could theoretically exist in the first place. Their calculations, published last week in the Monthly Notices of the Royal Astronomical Society, went beyond even what he had suspected.
Hypervelocity planets can indeed exist—and according to the research team’s simulations, they may approach speeds as high as 30 million miles per hour, making them some of the fastest-moving objects in the known universe.
“We asked what would happen if there were planets around hypervelocity stars,” Loeb says. “So we started with a simulation of a binary system, and then sprinkled planets around each of the stars.” Their calculations showed that, if the binary star system was ripped apart by gravitational forces near the galaxy’s central black hole, a small percentage of the planets would stay bound to one of the stars, either following them on their journey out of the galaxy, or diving more closely into the depths of the black hole. The majority of planets, however, would be flung away from their parent stars, traveling even faster to the edges of the Milky Way.
“Their speed can reach up to ten thousands kilometers per second—a few percent of the speed of light,” says Loeb. “If you imagine a civilization living on such a planet, they would have a tremendous journey.” The voyage from the center of the galaxy to the edge of the observable universe, he says, would take 10 billion years.
The potential existence of hypervelocity planets is far more than a mere curiosity, since it would provide us information about conditions near the center of the galaxy, and if planets can even form there. “It’s a very unusual environment, because the density of stars there is more than a million times than the density near the sun,” Loeb says. “There is a very high temperature, and every now and then the black hole at the center gets fed with gas, so it shines very brightly, which could in principle disrupt a system that tries to make planets.” His team’s calculations showed that, if planets can indeed form in this area, they should be observable when bound to hypervelocity stars.
None of these planets has been spotted, but Loeb hopes that some will be found in coming years. Just as astronomers have recently discovered hundreds of extrasolar planets using the transit method as part of NASA’s Kepler Mission, they can scrutinize hypervelocity stars in much the same way to spot these runaway planets. And if things progress along the same time frame as J.G. Hills’ 1988 prediction of hypervelocity stars, Loeb can expect to have his predictions confirmed within his lifetime—sometime around the year 2029.
February 25, 2012
You may remember learning the types of planets growing up: rocky planets, like Earth and Mars; gas giants, like Jupiter and Saturn; and ice giants, like Neptune and Uranus.
Now scientists at the Smithsonian Astrophysical Observatory (SAO) have discovered a new kind: a waterworld. The planet, named GJ1214b, is not merely covered with water like our oceans; most of it is water. “GJ1214b is like no planet we know of,” Zachory Berta, a graduate student at the SAO and lead author on the paper announcing the discovery, published online Tuesday in The Astrophysical Journal. “A huge fraction of its mass is made up of water.”
Contrary to what you might imagine, the “water” on GJ1214b is quite different from anything you’ve ever seen.”The water there is in really weird forms that we’re not used to on Earth,” Berta says. “There are substances that are like ice, but at a very high temperature, because the pressure is so high that the molecules are squeezed together. There is also this superfluid state of water that is more gaseous than the water we’re used to.”
If you have trouble picturing such an exotic alien waterworld, you’re not alone. “Frankly, I too have a lot of difficulty imagining what this would actually be like in person,” Berta says.
Located in the direction of the Ophiuchus, the planet is just 40 light years from Earth, making it a close neighbor compared to most of the stars in our galaxy. GJ1214b is 2.7 times Earth’s diameter and weighs nearly 7 times as much. The planet closely orbits a red-dwarf star every 38 hours, and has an estimated average temperature of 450° Fahrenheit.
Planets that orbit a star so closely do not typically contain any water, says Berta, so scientists believe that GJ1214b must have had an unusual history. “It couldn’t have formed that close, because all of the water would have evaporated off due to the heat,” he says. “So this planet probably had to have formed farther out, and somehow came inward.” Gravitational interactions with other planets may have pulled the waterworld closer in.
Berta and his thesis advisor, David Charbonneau, found the planet back in 2009 as part of the MEarth Project, which uses ground-based telescopes at the Fred Lawrence Whipple Observatory on Mount Hopkins in Arizona to discover habitable planets orbiting nearby red dwarf stars. “At the time, we had an inkling that this could be a waterworld,” Berta says. “We could measure the mass and the radius of the planet, so we knew its density, and the density was very low—too low to be explained by a big ball of rock.” The planet’s average density was calculated to be roughly 2 grams per cubic centimeter, far closer to water’s density of 1 g/cm3 than Earth’s average density of 5.5 g/cm3.
Still, with only limited information on the planet, the team couldn’t rule out other possibilities, such as a planet with a thick atmosphere of hydrogen and helium, which would similarly account for the low average density. But when the researchers were able to use the Hubble Telescope’s newly installed Wide Field Camera 3—specifically looking at light from the red dwarf star that traveled through the GJ1214b’s atmosphere before traveling towards us—they were able to rule out that possibility.
“If the big, puffy hydrogen envelope on the outside of the planet were there, we would see it, but we don’t,” says Berta. “So it looks like we’re dealing with the alternative—a planet with a whole bunch of water in it, and an atmosphere which is mostly water as well, which is consistent with what we see from the Hubble observations.” The research team describes the atmosphere hot and steamy.
Berta is less excited about finding the first of a new type of planet than the possibility of finding many more. “NASA’s Kepler telescope has found a number of planets that are the same size as this one, but they’re much more distant, so it’s hard to observe those planets in more detail,” he says. “This is interesting not because it’s something that we’ve never seen before and will never see again, but because it’s sort of a type specimen for all of these.”
He believes investments in telescopes and other observational equipment will continue to pay great dividends as we continue to search the galaxy for planets. “The James Webb Space Telescope [due to be launched in 2018] is NASA’s successor to Hubble. It will be great, because instead of just having a very rough picture of planets like these, we’ll be able to probe them more closely,” he says.
Berta is confident that within decades, astronomers will detect a smaller, cooler version of GJ1214b, which could theoretically harbor extraterrestrial life. “That’s the cool thing about astronomy,” he says. “As we continue to build better telescopes, we can find more and more.”