Rocket Reentry, Cosmic Babushka, and More

Rocket Reentry Puts on a Show

Did you see that?

Wednesday night at about 9:54 pm, a fireball lasting about 30 seconds streaked across the night sky, putting on a brilliant show for viewers in California, Nevada, Utah and Arizona.

Though many documenting the event via social media initially suspected a large meteor or even an early showing of the Perseid meteor shower, the relatively slow moving object broke apart in a way that suggested something different. Instead, the source of the spectacle was confirmed by NASA and other organizations to be “space junk”—human-made debris orbiting our world. This particular debris was the second stage of a Chinese Chang Zheng, or Long March, 7 (CZ-7) rocket that was launched June 25. The launch did not have a payload and was the first test of the mid-sized rocket that will probably play a significant role in the construction of China’s space station. According to Satview.org, the rocket stage was predicted to re-enter Earth’s atmosphere that day.

Currently, there are about 1,000 operational satellites in orbit around Earth. However that does not include the 500,000 pieces of tracked debris the size of a marble and larger and countless smaller fragments all orbiting our world at about 17,500 miles per hour. This includes everything from expended rockets, pieces of metal, a glove, and even paint chips that will, eventually, de-orbit and (mostly) burn up in Earth’s atmosphere, though traveling at that speed even these small bits do pose some risks to satellites and space travel.

For a chance to catch a glimpse of meteors soon, keep an eye to the sky next month when the Perseid meteor shower reaches its peak August 12th and is expected to put on quite a show this year, with up to 150 to 200 meteors visible an hour in dark conditions. –Elise Ricard

ESA’s Comet-Orbiter Nears the End of Its Mission

At the end of September, funding for the European Space Agency’s historic mission of the Rosetta spacecraft to Comet 67P/Churyumov-Gerasimenko will end—as will the mission itself. Ground controllers will gradually lower the vehicle’s orbit and guide the solar-winged spacecraft to a slow, “gentle” impact in the Ma’at region on the smaller lobe (the “head”) of the rubber duck-shaped comet. Several active pits have been discovered in the area, spewing jets of gas into space, so it’ll be interesting to obtain progressively closer views as Rosetta descends toward its final resting place. In preparation, controllers have turned off communication with the lost Philae lander, which was deployed from Rosetta to the surface in November 2014.

Not that there was all that much communicating going on, anyway. Ever since its rocky (or bouncy) touchdown, contact with the washing machine-sized probe was intermittent and fleeting at best, and after numerous attempts by mission teams to re-establish reliable communication, Philae fell silent after July 2015. The comet passed perihelion (its closest approach to the Sun) in August 2015, when it was 186 million kilometers (115 million miles) from our star. It is now moving away from the Sun and at this writing is 520 million kilometers (323 million miles) from it—roughly halfway between the orbits of Mars and Jupiter.

On Tuesday, a final message from Philae appeared on Twitter, and Philae’s fans are encouraged to send their farewells via social media. –Bing Quock

The Great Red... Heater?

A study in Nature this week implicates the Great Red Spot in the unusually high temperatures found in Jupiter’s upper atmosphere. In fact, temperatures in the upper atmospheres of all the Solar System’s giant planets are much hotter than would be expected if the Sun were the only heat source. But until now, scientists haven’t been able to identify an alternative heat source. The new paper surmises that this energy comes from below.

James O’Donoghue and colleagues designed observations to tease out that heat source, seeking temperature anomalies over the entire planet. Using NASA’s Infrared Telescope Facility, the researchers found high altitude temperatures much larger than anticipated whenever they looked at certain latitudes and longitudes in the planet’s southern hemisphere. “We could see almost immediately that our maximum temperatures at high altitudes were above the Great Red Spot far below—a weird coincidence or a major clue?” O’Donoghue says. A major clue, the teams says. They conclude that the storm in the Great Red Spot produces acoustic waves of energy that heat the upper atmosphere—an effect that has also been observed over the Andes Mountains.

Jupiter’s Great Red Spot is one of the marvels of our solar system. Discovered within years of Galileo’s introduction of telescopic astronomy in the 17th Century, its swirling pattern of colorful gases is often called a “perpetual hurricane.” The Great Red Spot has varied its size and color over the centuries, spans a distance equal to three earth-diameters, and has winds that take six days to complete one spin. Jupiter itself spins very quickly, completing one revolution in only ten hours.

“The extremely high temperatures observed above the storm appear to be the ‘smoking gun’ of this energy transfer, indicating that planet-wide heating is a plausible explanation for the ‘energy crisis,'” O’Donoghue says. A clue not just for Jupiter and the other gas giants in our solar system, but in exoplanets beyond, too. –Molly Michelson

The Cosmic Babushka

In a report published online in May, astronomers from the Institute of Astrophysics of the Canary Islands announced the discovery of the first known “triple bubble”—three concentric supernova remnants, located in M-33, a spiral galaxy nearly three million light years away in the constellation Triangulum.

The structures were detected from the Roque de Los Muchachos Observatory on La Palma, using a high-resolution spectrograph on the 4.2 meter (165-inch) William Herschel Telescope. That being the case, no optical image of the bubbles was taken, so they probably aren't quite as perfect and symmetrical-looking as in the artist’s representation (above).

Supernova remnants are gaseous clouds that have been left behind after the catastrophic explosion of a massive star, or supernova. The most famous example of a supernova remnant is the Crab Nebula, which was recently the subject of its own article in Science Today. At the center of the triple bubble is a star cluster where three separate supernova explosions are thought to have occurred, very roughly ten thousand years apart, creating the bubbles. Because of their curious, concentric nature, they have been compared to the Russian nested dolls known as matryoshkas (sometimes referred to as babushkas).

The researchers point out that each bubble contains more material than would be ejected by a supernova, so they must be formed largely from the interstellar material surrounding the stars. The shockwave from a supernova would sweep the material up, forming a bubble, but the fact that three bubbles have formed indicates that the first supernova—and even the second—still left enough behind to form the third bubble. A possible explanation, they suggest, is that nonuniformities, or clumps, in the interstellar medium are the source, and that each supernova may peel away some of each outer layers of the larger clumps, leaving enough behind to form the next bubble.

The discovery was made as part of a program called BUBBLY, designed to study “superbubbles”—giant bubbles of gas formed by supernova explosions and sculpted into vast, complex shapes by stellar winds emanating from neighboring stars. Studying superbubbles helps astronomers understand the interactions between stars and the interstellar medium, and this fascinating triple-bubble gives them a new puzzle to figure out. –Bing Quock

Looking for more Corvid Week content? Enjoy Bing Quock’s post from last year about the constellation Corvus the Crow.

Image: Gabriel Pérez/SMM (IAC)