Space and astronomy news
Host: Fraser Cain (@fcain)
Special Guest: Astrophysicist Katie Mack (@AstroKatie)
Guests:
Ramin Skibba (@raminskibba)
Charles Black (@charlesblack / sen.com/charles-black)
Brian Koberlein (@briankoberlein)
Continue reading “Weekly Space Hangout -March 13, 2015: Astrophysicist Katie Mack”
In March 2012, amateur astronomers began observing unusual clouds or plumes along the western limb of the red planet Mars. The plumes, in the southern hemisphere rose to over 200 kilometers altitude persisting for several days and then reappeared weeks later.
So a group of astronomers from Spain, the Netherlands, France, UK and USA have now reported their analysis of the phenomena. Their conclusions are inconclusive but they present two possible explanations.
Mars and mystery are synonymous. Among Martian mysteries, this one has persisted for three years. Our own planet, much more dynamic than Mars, continues to raise new questions and mysteries but Mars is a frozen desert. Frozen in time are features unchanged for billions of years.
In March 2012, the news of the observations caught the attention of Universe Today contributing writer Bob King. Reported on his March 22nd 2012 AstroBob blog page, the plumes or clouds were clear to see. The amateur observer, Wayne Jaeschke used his 14 inch telescope to capture still images which he stitched together into an animation to show the dynamics of the phenomena.
Now on February 16 of this year, a team of researchers led by Agustín Sánchez-Lavega of the University of the Basque Country in Bilbao, Spain, published their analysis in the journal Nature of the numerous observations, presenting two possible explanations. Their work is entitled: “An Extremely high-altitude plume seen at Mars morning terminator.”
The phenomena occurred over the Terra Cimmeria region centered at 45 degree south latitude. This area includes the tiger stripe array of magnetic fields emanating from concentrations of ferrous (iron) ore deposits on Mars; discovered by the Mars Global Surveyor magnetometer during low altitude aerobraking maneuvers at the beginning of the mission in 1998. Auroral events have been observed over this area from the interaction of the Martian magnetic field with streams of energetic particles streaming from the Sun. Sánchez-Lavega states that if these plumes are auroras, they would have to be over 1000 times brighter than those observed over the Earth.
The researchers also state that another problem with this scenario is the altitude. Auroras over Mars in this region have been observed up to 130 km, only half the height of the features. In the Earth’s field, aurora are confined to ionospheric altitudes – 100 km (60 miles). The Martian atmosphere at 200 km is exceedingly tenuous and the production of persistent and very bright aurora at such an altitude seems highly improbable.
The duration of the plumes – March 12th to 23rd, eleven days (after which observations of the area ended) and April 6th to 16th – is also a problem for this explanation. Auroral arcs on Earth are capable of persisting for hours. The Earth’s magnetic field functions like a capacitor storing charged particles from the Sun and some of these particles are discharged and produced the auroral oval and arcs. Over Mars, there is no equivalent capacitive storage of particles. Auroras over Mars are “WYSIWYG” – what you see is what you get – directly from the Sun. Concentrated solar high energy streams persisting for this long are unheard of.
The second explanation assessed by the astronomers is dust or ice crystals lofted to this high altitude. Again the altitude is the big issue. Martian dust storms will routinely lift dust to 60 km, still only one-third the height of the plumes. Martian dust devils will lift particles to 20 km. However, it is this second explanation involving ice crystals – Carbon Dioxide and Water – that the researchers give the most credence. In either instance, the particles must be concentrated and their reflectivity must account for the total brightness of the plumes. Ice crystals would be more easily transported to these heights, and also would be most highly reflective.
The paper also considered the shape of the plumes. The remarkable quality of modern amateur astrophotography cannot be overemphasized. Also the duration of the plumes was considered. By local noon and thereafter they were not observed. Again, the capabilities tendered by ground-based observations were unique and could not be duplicated by the present set of instruments orbiting Mars.
Still too many questions remain and the researchers state that “both explanations defy our present understanding of the Mars’ upper atmosphere.” By March 20th and 21st, the researchers summarized that at least 18 amateur astronomers observed the plume using from 20 to 40 cm telescopes (8 to 16 inch diameter) at wavelengths from blue to red. At Mars, the Mars Color Imager on MRO (MARCI) could not detect the event due to the 2 hour periodic scans that are compiled to make global images.
Of the many ground observations, the researchers utilized two sets from the venerable astrophotographers Don Parker and Daiman Peach. While observations and measurements were limited, the researchers analysis was exhaustive and included modeling assuming CO2, Water and dust particles. The researchers did find a Hubble observation from 1997 that compared favorably with the 2012 events and likewise modeled that event for comparison. However, Hubble results provided a single observation and the height estimate could not be narrowly constrained.
Explanation of these events in 2012 are left open-ended by the research paper. Additional observations are clearly necessary. With increased interest from amateurs and continued quality improvements plus the addition of the Maven spacecraft suite of instruments plus India’s Mars Orbiter mission, observations will eventually be gained and a Martian mystery solved to make way for yet another.
References:
An Extremely High-Altitude Plume seen at Mars’ Morning Terminator, Journal Nature, February 16, 2015
Amateur astronomer photographs curious cloud on Mars, AstroBob, March 22, 2012
This is the second animation from Dawn this year showing Ceres rotating, and at 43 pixels across the images are officially the best ever obtained!
NASA’s Dawn spacecraft is now on final approach to the 950 km (590 mile) dwarf planet Ceres, the largest world in the main asteroid belt and the biggest object in the inner Solar System that has yet to be explored closely. And, based on what one Dawn mission scientist has said, Ceres could very well be called the Solar System’s “hipster planet.”
“Ceres is a ‘planet’ that you’ve probably never heard of,” said Robert Mase, Dawn project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re excited to learn all about it with Dawn and share our discoveries with the world.”
Originally classified as a planet, Ceres was later categorized as an asteroid and then reclassified as a dwarf planet in 2006 (controversially along with far-flung Pluto.) Ceres was first observed in 1801 by astronomer Giuseppe Piazzi who named the object after the Roman goddess of agriculture, grain crops, fertility and motherly relationships. (Its orbit would later be calculated by German mathematician Carl Gauss.)
“You may not realize that the word ‘cereal’ comes from the name Ceres,” said Marc Rayman, mission director and chief engineer of the Dawn mission at JPL. “Perhaps you already connected with the dwarf planet at breakfast today.”
Ceres: part of this nutritionally-balanced Solar System!
The animation above was made from images taken by Dawn framing camera on January 25, 2015 from a distance of about 237,000 km (147,000 miles). These are now the highest-resolution views to date of the dwarf planet, 30% more detailed than those obtained by Hubble in January 2004.
And there’s that northern white spot again too… seen in observations from earlier this month and in the 2003-04 HST images, scientists still aren’t quite sure what it is. A crater wall? An exposed ice deposit? Something else entirely? We will soon find out.
“We are already seeing areas and details on Ceres popping out that had not been seen before. For instance, there are several dark features in the southern hemisphere that might be craters within a region that is darker overall,” said Carol Raymond, Dawn deputy principal investigator at JPL.
From now on, every observation of Ceres by Dawn will be the best we’ve ever seen! This new chapter of the spacecraft’s adventure has only just begun.
Dawn is scheduled to arrive at Ceres on March 6. Follow the progress of the Dawn mission here.
Source: NASA/JPL
*(Does this mean that Ceres has now gone “mainstream?” Hmm… oh well, it’s still cool.)
Host: Fraser Cain (@fcain)
Special Guest: Andy Weir , author of “The Martian”
Andy was first hired as a programmer for a national laboratory at age fifteen and has been working as a software engineer ever since. He is also a lifelong space nerd and a devoted hobbyist of subjects like relativistic physics, orbital mechanics, and the history of manned spaceflight. “The Martian” is his first novel.
Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Ramin Skibba (@raminskibba)
Brian Koberlein (@briankoberlein)
Dave Dickinson (@astroguyz / www.astroguyz.com)
Nicole Gugliucci (cosmoquest.org / @noisyastronomer)
Continue reading “Weekly Space Hangout – Jan 9, 2015: Andy Weir of “The Martian””
If NASA is so advanced, why are their pictures in black and white?
It’s a question that I’ve heard, in one form or another, for almost as long as I’ve been talking with the public about space. And, to be fair, it’s not a terrible inquiry. After all, the smartphone in my pocket can shoot something like ten high-resolution color images every second. It can automatically stitch them into a panorama, correct their color, and adjust their sharpness. All that for just a few hundred bucks, so why can’t our billion-dollar robots do the same?
The answer, it turns out, brings us to the intersection of science and the laws of nature. Let’s take a peek into what it takes to make a great space image…
Perhaps the one thing that people most underestimate about space exploration is the time it takes to execute a mission. Take Cassini, for example. It arrived at Saturn back in 2004 for a planned four-year mission. The journey to Saturn, however, is about seven years, meaning that the spacecraft launched way back in 1997. And planning for it? Instrument designs were being developed in the mid-1980s! So, when you next see an astonishing image of Titan or the rings here at Universe Today, remember that the camera taking those shots is using technology that’s almost 30 years old. That’s pretty amazing, if you ask me.
But even back in the 1980s, the technology to create color cameras had been developed. Mission designers simply choose not to use it, and they had a couple of great reasons for making that decision.
Perhaps the most practical reason is that color cameras simply don’t collect as much light. Each “pixel” on your smartphone sensor is really made up of four individual detectors: one red, one blue, two green (human eyes are more sensitive to green!). The camera’s software combines the values of those detectors into the final color value for a given pixel. But, what happens when a green photon hits a red detector? Nothing, and therein lies the problem. Color sensors only collect a fraction of the incoming light; the rest is simply lost information. That’s fine here on Earth, where light is more or less spewing everywhere at all times. But, the intensity of light follows one of those pesky inverse-square laws in physics, meaning that doubling your distance from a light source results in it looking only a quarter as bright.
That means that spacecraft orbiting Jupiter, which is about five times farther from the Sun than is the Earth, see only four percent as much light as we do. And Cassini at Saturn sees the Sun as one hundred times fainter than you or I. To make a good, clear image, space cameras need to make use of all the little light available to them, which means making do without those fancy color pixels.
The darkness of the solar system isn’t the only reason to avoid using a color camera. To the astronomer, light is everything. It’s essentially our only tool for understanding vast tracts of the Universe and so we must treat it carefully and glean from it every possible scrap of information. A red-blue-green color scheme like the one used in most cameras today is a blunt tool, splitting light up into just those three categories. What astronomers want is a scalpel, capable of discerning just how red, green, or blue the light is. But we can’t build a camera that has red, orange, yellow, green, blue, and violet pixels – that would do even worse in low light!
Instead, we use filters to test for light of very particular colors that are of interest scientifically. Some colors are so important that astronomers have given them particular names; H-alpha, for example, is a brilliant hue of red that marks the location of hydrogen throughout the galaxy. By placing an H-alpha filter in front of the camera, we can see exactly where hydrogen is located in the image – useful! With filters, we can really pack in the colors. The Hubble Space Telescope’s Advanced Camera for Surveys, for example, carries with it 38 different filters for a vast array of tasks. But each image taken still looks grayscale, since we only have one bit of color information.
At this point, you’re probably saying to yourself “but, but, I KNOW I have seen color images from Hubble before!” In fact, you’ve probably never seen a grayscale Hubble image, so what’s up? It all comes from what’s called post-processing. Just like a color camera can combine color information from three detectors to make the image look true-to-life, astronomers can take three (or more!) images through different filters and combine them later to make a color picture. There are two main approaches to doing this, known colloquially as “true color” and “false color.”
True color images strive to work just like your smartphone camera. The spacecraft captures images through filters which span the visible spectrum, so that, when combined, the result is similar to what you’d see with your own eyes. The recently released Galileo image of Europa is a gorgeous example of this.
False color images aren’t limited by what our human eyes can see. They assign different colors to different features within an image. Take this famous image of the Crab Nebula, for instance. The red in the image traces oxygen atoms that have had electrons stripped away. Blue traces normal oxygen and green indicates sulfur. The result is a gorgeous image, but not one that we could ever hope to see for ourselves.
So, if we can make color images, why don’t we always? Again, the laws of physics step in to spoil the fun. For one, things in space are constantly moving, usually really, really quickly. Perhaps you saw the first color image of comet 67P/Churyumov-Gerasimenko released recently. It’s kind of blurry, isn’t it? That’s because both the Rosetta spacecraft and the comet moved in the time it took to capture the three separate images. When combined, they don’t line up perfectly and the image blurs. Not great!
But it’s the inverse-square law that is the ultimate challenge here. Radio waves, as a form of light, also rapidly become weaker with distance. When it takes 90 minutes to send back a single HiRISE image from the Mars Reconnaissance Orbiter, every shot counts and spending three on the same target doesn’t always make sense.
Finally, images, even color ones, are only one piece of the space exploration puzzle. Other observations, from measuring the velocity of dust grains to the composition of gases, are no less important to understanding the mysteries of nature. So, next time you see an eye-opening image, don’t mind that it’s in shades of gray. Just imagine everything else that lack of color is letting us learn.
Crazy things can happen when galaxies collide, as they sometimes do. Although individual stars rarely impact each other, the gravitational interactions between galaxies can pull enormous amounts of gas and dust into long streamers, spark the formation of new stars, and even kick objects out into intergalactic space altogether. This is what very well may have happened to SDSS1133, a suspected supermassive black hole found thousands of light-years away from its original home.
Seen above in a near-infrared image acquired with the Keck II telescope in Hawaii, SDSS1133 is the 40-light-year-wide bright source observed 2,300 light-years out from the dwarf galaxy Markarian 177, located 90 million light-years away in the constellation Ursa Major (or, to use the more familiar asterism, inside the bowl of the Big Dipper.)
The two bright spots at the disturbed core of Markarian 177 are thought to indicate recent star formation, which could have occurred in the wake of a previous collision.
“We suspect we’re seeing the aftermath of a merger of two small galaxies and their central black holes,” said Laura Blecha, an Einstein Fellow in the University of Maryland’s Department of Astronomy and a co-author of an international study of SDSS1133. “Astronomers searching for recoiling black holes have been unable to confirm a detection, so finding even one of these sources would be a major discovery.”
Interactions between supermassive black holes during a galactic collision would also result in gravitational waves, elusive phenomena predicted by Einstein that are high on astronomers’ most-wanted list of confirmed detections.
Read more: “Spotter’s Guide” to Detecting Black Hole Collisions
Watch an animation of how the suspected collision and subsequent eviction may have happened:
But besides how it got to where it is, the true nature of SDSS1133 is a mystery as well.
The persistently bright near-infrared source has been detected in observations going back at least 60 years. Whether or not SDSS1133 is indeed a supermassive black hole has yet to be determined, but if it isn’t then it’s a very unusual type of extremely massive star known as an LBV, or Luminous Blue Variable. If that is the case though, it’s peculiar even for an LBV; SDSS1133 would have had to have been continuously pouring out energy in a for over half a century until it exploded as a supernova in 2001.
To help determine exactly what SDSS1133 is, continued observations with Hubble’s Cosmic Origins Spectrograph instrument are planned for Oct. 2015.
“We found in the Pan-STARRS1 imaging that SDSS1133 has been getting significantly brighter at visible wavelengths over the last six months and that bolstered the black hole interpretation and our case to study SDSS1133 now with HST,” said Yanxia Li, a UH Manoa graduate student involved in the research.
And, based on data from NASA’s Swift mission the UV emission of SDSS1133 hasn’t changed in ten years, “not something typically seen in a young supernova remnant” according to Michael Koss, who led the study and is now an astronomer at ETH Zurich.
Regardless of what SDSS1133 turns out to be, the idea of such a massive and energetic object soaring through intergalactic space is intriguing, to say the least.
The study will be published in the Nov. 21 edition of Monthly Notices of the Royal Astronomical Society.
Source: Keck Observatory
We’ve all heard that the Universe is expanding, but why is it expanding? What’s the force pushing everything outwards?
If still you don’t know that we live in an expanding Universe, then I’m clearly not doing my job.
And so once more, with feeling… the Universe is expanding. But that certainly doesn’t answer all the questions that go along with the it.
Like what’s the Universe expanding into? Which we did in another video, which I’ll list at the end of this episode. You might also want to know why is the Universe expanding? What’s making this happen? Did it give up its gym membership? Did it sign up for the gallon of ice cream of the month club? Has it completely embraced the blerch?
Edwin Hubble, the astronomer made famous by being named after a space telescope, provided the definitive evidence that the Universe was expanding. Observing distant galaxies, he observed they were fleeing outwards, in fact he was able to come up with calculations to show just how fast they were moving away from us.
Or to be more precise, he was able to show how fast all the galaxies are moving away from each other. Which was your question! Just like a minute ago! See you’re just as smart as Hubble!
So up until about 15 years ago, the only answer was momentum. The idea was that the Universe received all the energy it needed for its expansion in the first few moments after the Big Bang.
Imagine the beginning of the Universe, BOOM, like an explosion from a gun. And all the rest of the expansion is the Universe coasting outwards. For the longest time, astronomers were trying to figure out what this momentum would mean for the future of the Universe.
Would the mutual gravity of all the objects in the Universe cause it to slow to a halt at some point in the distant future, or maybe even collapse in on itself, leading to a Big Crunch? Or just clump up in piles and stay on the couch all summer because it’s maybe a little lazy and isn’t ready to start going back to the gym yet?
In 1999, astronomers discovered something completely unexpected… dark energy. As they were doing their observations to figure out exactly how the Universe would coast to a stop, they discovered that it’s actually speeding up. It’s as if that bullet is actually a rocket and it’s accelerating.
Now it appears that the Universe will not only expand forever, but the speed of its expansion will continue to accelerate faster and faster. So what’s causing this expansion? Currently, we believe it’s mostly momentum left over from the Big Bang, and the force of dark energy will be accelerating this expansion. Forever.
How do you feel about a rapidly accelerating expanding Universe? Tell us in the comments below.
And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
Host: Fraser Cain (@fcain)
Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Brian Koberlein (@briankoberlein)
Nicole Gugliucci (cosmoquest.org / @noisyastronomer)
Continue reading “Weekly Space Hangout – Nov. 7, 2014: Ship Updates & Solar System Formation”
Host: Fraser Cain (@fcain)
Guests:
Ramin Skibba (@raminskibba)
Continue reading “Weekly Space Hangout – Oct. 24, 2014”
On a summer night, high above our heads, where the Northern Crown and Herdsman meet, a titanic new galaxy is being born 4.5 billion light years away. You and I can’t see it, but astronomers using the Hubble Space Telescope released photographs today showing the merger of two enormous elliptical galaxies into a future heavyweight adorned with a dazzling string of super-sized star clusters.
The two giants, each about 330,000 light years across or more than three times the size of the Milky Way, are members of a large cluster of galaxies called SDSS J1531+3414. They’ve strayed into each other’s paths and are now helpless against the attractive force of gravity which pulls them ever closer.
Galactic mergers are violent events that strip gas, dust and stars away from the galaxies involved and can alter their appearances dramatically, forming large gaseous tails, glowing rings, and warped galactic disks. Stars on the other hand, like so many pinpoints in relatively empty space, pass by one another and rarely collide.
Elliptical galaxies get their name from their oval and spheroidal shapes. They lack the spiral arms, rich reserves of dust and gas and pizza-like flatness that give spiral galaxies like Andromeda and the Milky Way their multi-faceted character. Ellipticals, although incredibly rich in stars and globular clusters, generally appear featureless.
But these two monster ellipticals appear to be different. Unlike their gas-starved brothers and sisters, they’re rich enough in the stuff needed to induce star formation. Take a look at that string of blue blobs stretching across the center – astronomers call it a great example of ‘beads on a string’ star formation. The knotted rope of gaseous filaments with bright patches of new star clusters stems from the same physics which causes rain or water from a faucet to fall in droplets instead of streams. In the case of water, surface tension makes water ‘snap’ into individual droplets; with clouds of galactic gas, gravity is the great congealer.
Nineteen compact clumps of young stars make up the length of this ‘string’, woven together with narrow filaments of hydrogen gas. The star formation spans 100,000 light years, about the size of our galaxy, the Milky Way. Astronomers still aren’t sure if the gas comes directly from the galaxies or has condensed like rain from X-ray-hot halos of gas surrounding both giants.
The blue arcs framing the merger have to do with the galaxy cluster’s enormous gravity, which warps the fabric of space like a lens, bending and focusing the light of more distant background galaxies into curvy strands of blue light. Each represents a highly distorted image of a real object.
Simulation of the Milky Way-Andromeda collision 4 billion years from now
Four billion years from now, Milky Way residents will experience a merger of our own when the Andromeda Galaxy, which has been heading our direction at 300,000 mph for millions of years, arrives on our doorstep. After a few do-si-dos the two galaxies will swallow one another up to form a much larger whirling dervish that some have already dubbed ‘Milkomeda’. Come that day, perhaps our combined galaxies will don a string a blue pearls too.