Astronauts aboard the @Space_Station captured this amazing image of the Moon’s shadow over the U.S. during #SolarEclipse2017.
TODAY IN HISTORY: Belka and Strelka, pride of the Soviet Union, became the first dogs to fly in space and return safely to Earth, August 19, 1960.
This striking Jovian vista was created by citizen scientists Gerald Eichstädt and Seán Doran using data from the JunoCam imager on NASA’s Juno spacecraft.
The tumultuous Great Red Spot is fading from Juno’s view while the dynamic bands of the southern region of Jupiter come into focus. North is to the left of the image, and south is on the right.
The image was taken on July 10, 2017 at 7:12 p.m. PDT (10:12 p.m. EDT), as the Juno spacecraft performed its seventh close flyby of Jupiter. At the time the image was taken, the spacecraft was 10,274 miles (16,535 kilometers) from the tops of the clouds of the planet at a latitude of -36.9 degrees.
At the time TFN started taking observations (blue points), the flux was way down(!!); and it continued to change quite significantly over the course of a couple hours. At the end of the TFN visibility window, it had returned to the same level of brightness from the previous day, and this continued for the time it was observed at OGG. This short term variability was also independently detected by colleagues observing at the TJO telescope in Spain, so the chances are very good that it is real (not a problem with the data). Unfortunately what we saw didn’t last long, only a couple of hours. But we don’t have any coverage just before it, from 94.1-94.3 on this x-axis, so we could only guess to what happened during that time: did we catch it on the way up from a quick, big drop, or was the event more shallow and gradual?
I have been reminded that its probably a good idea to note that the data shown here are normalized to unity. Normalizing to unity shows the depths of the dips plus any long term dimming trends that may be occurring, which is what we care about anyway (the total amount of stuff is between us and the star). We will need a lot more data (when the star is not dipping) to address this long term dimming properly, and at this point its best to avoid such speculation.
A new analysis of data from ESO’s Very Large Telescope and other telescopes suggests that the orbits of stars around the supermassive black hole at the centre of the Milky Way may show the subtle effects predicted by Einstein’s general theory of relativity. There are hints that the orbit of the star S2 is deviating slightly from the path calculated using classical physics. This tantalising result is a prelude to much more precise measurements and tests of relativity that will be made using the GRAVITY instrument as star S2 passes very close to the black hole in 2018.
The GhanaSat-1―Ghana’s first satellite―began its orbit recently, with a little help from some friends.
The cubesat, built by a Ghanaian engineering team at All Nations University, was delivered to NASA’s International Space Station in June on a SpaceX rocket that took off from pad 39a at Kennedy Space Center, a NASA spokesperson confirmed.
The GhanaSat-1 deployed into orbit from the Center in July, and is now operational, according to project manager Richard Damoah, a Ghanaian professor and assistant research scientist at NASA.
“This particular satellite has two missions,” Damoah told TechCrunch. “It has cameras on board for detailed monitoring of the coastlines of Ghana. Then there’s an educational piece―we want to use it to integrate satellite technology into high school curriculum,” he said.
GhanaSat-1 will send a signal to a ground station at All Nations University’s Space Systems and Technology Laboratory. That’s where it was developed by a team of engineers that included Benjamin Bonsu, Ernest Teye Matey, and Joseph Quansah.
We go over the current normalized flux graph of Tabby’s star for August 4th, 2017 by showing a light curve update from Bruce Gary showing some new dimming of Tabby’s Star. We also show a potential sinusoidal variation in the flux data with a 34 day periodicity.
Comets that move regularly into the inner system are found to be, on average, as much as four times smaller than long-period comets, those moving only rarely near the Sun. Moreover, there are seven times more long-period comets in the size range of one kilometer in diameter and above than had previously been thought. In the eight months of the study period, three to five times more long-period comets were observed moving in the vicinity of the Sun than had been predicted.
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Co-author Amy Mainzer (JPL), principal investigator of the NEOWISE mission, points out that, traveling much faster than asteroids, long-period comets like these, many of them quite large, have to be factored into our analyses of impact risk. We’re developing an extensive catalog of near-Earth objects, but a long-period comet dislodged from the Oort Cloud, moving faster than any near-Earth asteroid, poses a risk that is badly in need of assessment.
yikes - damocloids in particular are the worst - very difficult to see in advance, probably relatively large, and moving at very high relative velocity to Earth
The analysis, posted on DES’s website today and based on observations of 26 million galaxies in a large swath of the southern sky, tweaks estimates only a little. It draws the pie chart of the universe as 74 percent dark energy and 21 percent dark matter, with galaxies and all other visible matter — everything currently known to physicists — filling the remaining 5 percent sliver.
These rotation curves showed something unexpected: rather than remaining steady, velocities quickly tailed off as measurements moved away from the center of the galaxies. In fact, the curves looked a lot like what you’d expect based on the description above, if there were no dark matter around. Comparisons with models of galaxy behavior confirmed and quantified this idea: the curves could be reproduced using models that had a minimal dark matter component.
The authors checked a number of alternative explanations, like the gravitational influence of nearby galaxies or orbiting dwarf galaxies, but neither of these appeared to be a major factor. The drop in rotational velocity was also symmetric around the galaxy, which would seem to rule out localized influences. When the authors added local (and thus more current) galaxies to the analysis, the analysis showed that the faction of dark matter in galaxies seems to go down as you go further back in time.
It might be tempting to view this all as a problem for the idea of dark matter. But it’s worth noting that the primary alternatives to dark matter, modified versions of gravity, wouldn’t explain the situation either, as they suggest gravity changes over distance but not time.
The authors of the new paper see a number of possible explanations. One is that the early galaxies are very gas-rich, and these clouds of gas can experience local instabilities or collisions. This could cause the regular matter in the inner galaxy to compact, resulting in a normal-matter-dominated portion of the galaxy. The other possibility is that rather than forming the seeds of galaxies, dark matter starts off rather diffuse and takes time to form a disk-like structure that mirrors that of the visible galaxy. Either of these would explain the apparent matter dominance.
The planet, described in a study published today in Nature, is called WASP-121b. It belongs to a class of exoplanets called hot Jupiters — worlds that are so big and hot that they are fairly easy to study, thus allowing astronomers to hone their skills and confirm their theories. Today’s discovery confirms what astronomers suspected: super hot gas giants outside our Solar System can have a stratosphere.
WASP-121b is massive — nearly twice the size of our Jupiter. And because it orbits much closer to its host star than Mercury orbits around the Sun, its atmosphere heats up to more than 4,500 degrees Fahrenheit. (At that temperature, you could boil iron.) Using NASA’s Hubble Space Telescope, the researchers were able to detect glowing water molecules in the planet’s atmosphere, a clear signal that WASP-121b has a stratosphere. What exactly is causing the stratosphere is more of a mystery, but it could be gases like vanadium oxide and titanium oxide, which are believed to act like the ozone on Earth, the study says.
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Worlds like WASP-121b are way too hot to possibly host any kind of life as we know it — whether or not they have a stratosphere. But studying them is still key: it allows researchers to test their theories and learn more about the underlying physics. “They are a first step towards honing our skills, developing our tools, getting ready for the things that are more Earth-like,” says Kevin Heng, the director of the Center for Space and Habitability at the University of Bern. “This is the first step in a long road.”
This morning David and I put out a paper on the arXiv that represents the culmination of years of work searching for the signature of exomoons in the population of stars examined by the Kepler Mission. After carefully analyzing an ensemble of the highest quality planetary transit signals, we have determined that exomoons appear to be quite rare in the inner regions of star systems (regions of space close to the host star). This finding was both remarkable and, frankly, a bit disappointing.
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In any case, there was another result in our paper that may make a considerably larger splash, which you may have even read about in the news, or soon will: We announced our identification of a single exomoon candidate, indeed the strongest candidate we’ve seen in the five year history of the Hunt for Exomoons with Kepler (HEK) collaboration. The system, Kepler-1625 b, has withstood a host of preliminary tests aimed at ruling out the presence of a moon, and our proposal to observe this system with the Hubble Space Telescope was recently accepted. We are thrilled to get the chance to observe with Hubble, and hope that the observation will confirm our suspicion unambiguously that this is a genuine exomoon detection, which would be the first of its kind.
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