Universe Today

February 20, 2014March 8, 2017 by Fraser Cain

Could Jupiter Become A Star?

NASA’s Galileo spacecraft arrived at Jupiter on December 7, 1995, and proceeded to study the giant planet for almost 8 years. It sent back a tremendous amount of scientific information that revolutionized our understanding of the Jovian system. By the end of its mission, Galileo was worn down. Instruments were failing and scientists were worried they wouldn’t be able to communicate with the spacecraft in the future. If they lost contact, Galileo would continue to orbit the Jupiter and potentially crash into one of its icy moons.

Galileo would certainly have Earth bacteria on board, which might contaminate the pristine environments of the Jovian moons, and so NASA decided it would be best to crash Galileo into Jupiter, removing the risk entirely. Although everyone in the scientific community were certain this was the safe and wise thing to do, there were a small group of people concerned that crashing Galileo into Jupiter, with its Plutonium thermal reactor, might cause a cascade reaction that would ignite Jupiter into a second star in the Solar System.

Hydrogen bombs are ignited by detonating plutonium, and Jupiter’s got a lot of hydrogen.Since we don’t have a second star, you’ll be glad to know this didn’t happen. Could it have happened? Could it ever happen? The answer, of course, is a series of nos. No, it couldn’t have happened. There’s no way it could ever happen… or is there?

Jupiter is mostly made of hydrogen, in order to turn it into a giant fireball you’d need oxygen to burn it. Water tells us what the recipe is. There are two atoms of hydrogen to one atom of oxygen. If you can get the two elements together in those quantities, you get water.

In other words, if you could surround Jupiter with half again more Jupiter’s worth of oxygen, you’d get a Jupiter plus a half sized fireball. It would turn into water and release energy. But that much oxygen isn’t handy, and even though it’s a giant ball of fire, that’s still not a star anyway. In fact, stars aren’t “burning” at all, at least, not in the combustion sense.

Jupiter as imaged by Michael Phillips on July 25th, 2009... note the impact scar discovered by Anthony Wesley to the lower left. — Jupiter as imaged by Michael Phillips on July 25th, 2009.

Our Sun produces its energy through fusion. The vast gravity compresses hydrogen down to the point that high pressure and temperatures cram hydrogen atoms into helium. This is a fusion reaction. It generates excess energy, and so the Sun is bright. And the only way you can get a reaction like this is when you bring together a massive amount of hydrogen. In fact… you’d need a star’s worth of hydrogen. Jupiter is a thousand times less massive than the Sun. One thousand times less massive. In other words, if you crashed 1000 Jupiters together, then we’d have a second actual Sun in our Solar System.

But the Sun isn’t the smallest possible star you can have. In fact, if you have about 7.5% the mass of the Sun’s worth of hydrogen collected together, you’ll get a red dwarf star. So the smallest red dwarf star is still about 80 times the mass of Jupiter. You know the drill, find 79 more Jupiters, crash them into Jupiter, and we’d have a second star in the Solar System.

There’s another object that’s less massive than a red dwarf, but it’s still sort of star like: a brown dwarf. This is an object which isn’t massive enough to ignite in true fusion, but it’s still massive enough that deuterium, a variant of hydrogen, will fuse. You can get a brown dwarf with only 13 times the mass of Jupiter. Now that’s not so hard, right? Find 13 more Jupiters, crash them into the planet?

As was demonstrated with Galileo, igniting Jupiter or its hydrogen is not a simple matter.
We won’t get a second star unless there’s a series of catastrophic collisions in the Solar System.
And if that happens… we’ll have other problems on our hands.

February 20, 2014April 26, 2016 by Elizabeth Howell

Asteroid Swarm ‘Pounded’ Pulsar Star, Causing Changes Visible From Earth

Artist's impression of an asteroid breaking up. Credit: NASA/JPL-Caltech

When you throw a bunch of rock and debris at a rapidly spinning star, what happens? A new study suggests that so-called pulsar stars change their dizzying spin rate as asteroids fall into the gaseous mass. This conclusion comes from observations of one pulsar (PSR J0738-4042) that is being “pounded” with debris from rocks, researchers said.

Lying 37,000 light-years from our planet in the southern constellation Puppis, this supernova remnant’s environment is swarming with rocks, radiation and “winds of particles”. One of those rocks likely was more than a billion metric tonnes in mass, which is nowhere near the mass of Earth (5.9 sextillion tonnes), but is still substantial.

“If a large rocky object can form here, planets could form around any star. That’s exciting,” stated Ryan Shannon, a researcher with the Commonwealth Scientific and Industrial Research Organisation who participated in the study.

Pulsars are sometimes called the clocks of the universe because their spins, fast as they are, precisely emit radio beams with each revolution — a beam that can be seen from Earth if our planet and the star are aligned in the right way. A 2008 study by Shannon and others predicted the spin could be altered by debris falling into the pulsar, which this new research appears to confirm.

Artist's conception of stellar rubble around pulsar 4U 0142+61. Credit: NASA/JPL-Caltech — Artist’s conception of stellar rubble around pulsar 4U 0142+61. Credit: NASA/JPL-Caltech

“We think the pulsar’s radio beam zaps the asteroid, vaporizing it. But the vaporized particles are electrically charged and they slightly alter the process that creates the pulsar’s beam,” Shannon said.

As stars explode, the researchers further suggest that not only do they leave behind a pulsar star remnant, but they also throw out debris that could then fall back towards the pulsar and create a debris disc. Another pulsar, J0146+61, appears to display this kind of disc. As with other protoplanetary systems, it’s possible the small bits of matter could gradually clump together to form bigger rocks.

You can read the study in Astrophysical Journal Letters or in preprint version on Arxiv. The study was led by Paul Brook, a Ph.D. student co-supervised by the University of Oxford and CSIRO. Observations were performed with the Hartebeesthoek Radio Astronomy Observatory in South Africa, and CSIRO’s Parkes radio telescope.

Source: Commonwealth Scientific and Industrial Research Organisation

February 20, 2014December 23, 2015 by Elizabeth Howell

New Planet-Hunting Telescope To Join Search For Alien Earths In 2024

Artist's conception of exoplanet systems that could be observed by PLAnetary Transits and Oscillations of stars (PLATO), a European Space Agency telescope. Credit: ESA - C. Carreau

How could life arise in young solar systems? We’re still not sure of the answer on Earth, even for something as basic as if water arose natively on our planet or was carried in from other locations. Seeking answers to life’s beginnings will require eyes in the sky and on the ground looking for alien worlds like our own. And just yesterday, the European Space Agency announced it is going to add to that search.

The newly selected mission is called PLATO, for Planetary Transits and Oscillations. Like NASA’s Kepler space telescope, PLATO will scan the sky in search of stars that have small, periodic dips in their brightness that happen when planets go across their parent star’s face.

“The mission will address two key themes of Cosmic Vision: what are the conditions for planet formation and the emergence of life, and how does the solar system work,” stated ESA, referring to its plan for space science missions that extends from 2015 to 2025.

An exoplanet seen from its moon (artist's impression). Via the IAU. — An exoplanet seen from its moon (artist’s impression). Via the IAU.

PLATO will operate far from Earth in a spot known as L2, a relatively stable Lagrange point about 1.5 million kilometers (930,000 miles) away from Earth in the opposite direction from the sun. Sitting there for at least six years, the observatory (which is actually made up of 34 small telescopes and cameras) will examine up to a million stars across half of the sky.

A 2010 science proposal of the mission suggests that the satellite gather enough planetary transits to achieve three things:

Find “statistically significant” Earth-mass planets in the habitable regions of several kinds of main-sequence stars;
Figure out the radius and mass of the star and any planets with 1% accuracy, and estimate the age of exoplanet systems with 10% accuracy;
Better determine the parameters of different kinds of planets, ranging from brown dwarfs (failed stars) to gas giants to rocky planets, all the way down to those that are smaller than Earth.

Artist’s impression of the deep blue planet HD 189733b, based on observations from the Hubble Space Telescope. Credit: NASA/ESA.

Adding PLATO’s observations to those telescopes on the ground that look at the radial velocity of planets, researchers will also be able to figure out each planet’s mass and radius (which then leads to density calculations, showing if it is made of rock, gas, or something else).

“The mission will identify and study thousands of exoplanetary systems, with an emphasis on discovering and characterising Earth-sized planets and super-Earths in the habitable zone of their parent star – the distance from the star where liquid surface water could exist,” ESA stated this week.

The telescope was selected from four competing proposals, which were EChO (the Exoplanet CHaracterisation Observatory), LOFT (the Large Observatory For x-ray Timing), MarcoPolo-R (to collect and return a sample from a near-Earth asteroid) and STE-Quest (Space-Time Explorer and QUantum Equivalence principle Space Test).

You can read more about PLATO at this website. It’s expected to launch from Kourou, French Guiana on a Soyuz rocket in 2024, with a budget of 600 million Euros ($822 million). And here’s more information on the Cosmic Vision and the two other M-class missions launching in future years, Euclid and Solar Orbiter.

Source: European Space Agency

February 20, 2014December 23, 2015 by Elizabeth Howell

Dense Gas Clouds Blot The View Of Supermassive Black Holes

A supermassive black hole has been found in an unusual spot: an isolated region of space where only small, dim galaxies reside. Image credit: NASA/JPL-Caltech — A team of astronomers from South Africa have noticed a series of supermassive black holes in distant galaxies that are all spinning in the same direction. Credit: NASA/JPL-Caltech

Gas around supermassive black holes tends to clump into immense clouds, periodically blocking the view of these huge X-ray sources from Earth, new research reveals.

Observations of 55 of these “galactic nuclei” revealed at least a dozen times when an X-ray source dimmed for a time as short as a few hours or as long as years, which likely happened when a gas cloud blotted out the signal seen from Earth. This is different than some previous models suggesting the gas was more uniform.

“Evidence for the clouds comes from records collected over 16 years by NASA’s Rossi X-ray Timing Explorer, a satellite in low-earth orbit equipped with instruments that measured variations in X-ray sources,” stated the Royal Astronomical Society.

“Those sources include active galactic nuclei, brilliantly luminous objects powered by supermassive black holes as they gather and condense huge quantities of dust and gas.”

You can read more in the Monthly Notices of the Royal Astronomical Society or in preprint version on Arxiv. Below are some different versions of the YouTube video on top, one with weather symbols and another showing a diagram with varying X-ray emission.

The research was led by Alex Markowitz, an astrophysicist at the University of California, San Diego and the Karl Remeis Observatory in Bamberg, Germany.

There have been a few neat studies lately looking at the environment around these huge objects. One examined how the black hole fuels itself, while another suggested that perhaps these singularities formed as twins before evolving.

Source: Royal Astronomical Society

February 19, 2014December 23, 2015 by Ken Kremer

Opportunity rover Spied atop Martian Mountain Ridge from Orbit – Views from Above and Below

Opportunity Rover on ‘Murray Ridge’ Seen From Orbit on Valentine’s Day 2014
The telescopic High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter caught this view of NASA’s Mars Exploration Rover Opportunity on Feb. 14, 2014 by the summit of Solander Point. The red arrow points to Opportunity at the center of the image. Blue arrows point to tracks left by the rover since it entered the area seen here, in October 2013. The scene covers a patch of ground about one-quarter mile (about 400 meters) wide. North is toward the top. The location is the “Murray Ridge” section of the western rim of Endeavour Crater. Credit: NASA/JPL-Caltech/Univ. of Arizona
See below corresponding surface view snapped by Opportunity from this location[/caption]

NASA’s renowned Mars rover Opportunity has been spied anew in a fabulous new photo captured just days ago by NASA’s ‘Spy in the Sky’ orbiter circling overhead the Red Planet. See Opportunity from above and below – from today’s location. See orbital view above – just released today.

The highly detailed image was freshly taken on Feb. 14 (Valentine’s Day 2014) by the telescopic High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter (MRO) as the decade old Opportunity was investigating the tasty alien terrain on ‘Murray Ridge’ – nearby the celebrated ‘jelly doughnut’ rock by the summit of Solander Point. See surface views below.

The fabulous orbital image shows not only rover Opportunity at her location today, but also the breathtaking landscape around the robots current location as well as some of the wheel tracks created by the Martian mountaineer as she climbed from the plains below up to near the peak of Solander Point.

The scene is narrowly focused on a spot barely one-quarter mile (400 meters) wide.

Murray Ridge and Solander Point lie at the western rim of a vast crater named Endeavour that spans some 22 kilometers (14 miles) in diameter.

Here is the corresponding Martian surface view snapped by Opportunity on Feb. 16, 2014 (looking back and down to Endeavour crater), while she’s being imaged from Mars orbit on Feb. 14, 2014:

NASA’s Opportunity rover was imaged here from Mars orbit by MRO HiRISE camera on Feb. 14, 2014. This mosaic shows Opportunity’s view today while looking back to vast Endeavour crater from atop Murray Ridge by summit of Solander Point. Opportunity captured this photomosaic view on Feb. 16, 2014 (Sol 3579) from the western rim of Endeavour Crater where she is investigating outcrops of potential clay minerals formed in liquid water. Assembled from Sol 3579 colorized navcam raw images. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer-kenkremer.com

Endeavour is an impact scar created billions of years ago. See our 10 Year Opportunity traverse map below.

And believe it or not, that infamous ‘jelly doughnut’ rock was actually the impetus for this new imaging campaign by NASA’s MRO Martian ‘Spysat.’

To help solve the mystery of the origin of the shiny 1.5 inches wide (4 centimeters) ‘jelly doughnut’ rock, dubbed ‘Pinnacle Island’, the science team decided to enlist the unparalleled capabilities of the HiRISE camera and imaging team in pursuit of answers.

Opportunity by Solander Point peak – 2nd Mars Decade Starts here! NASA’s Opportunity rover captured this panoramic mosaic on Dec. 10, 2013 (Sol 3512) near the summit of “Solander Point” on the western rim of Endeavour Crater where she starts Decade 2 on the Red Planet. She is currently investigating outcrops of potential clay minerals formed in liquid water on her 1st mountain climbing adventure. Assembled from Sol 3512 navcam raw images. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer-kenkremer.com — Opportunity by Solander Point peak – 2nd Mars Decade Starts here!
NASA’s Opportunity rover captured this panoramic mosaic on Dec. 10, 2013 (Sol 3512) near the summit of “Solander Point” on the western rim of Endeavour Crater where she starts Decade 2 on the Red Planet. She is currently investigating outcrops of potential clay minerals formed in liquid water on her 1st mountain climbing adventure. Assembled from Sol 3512 navcam raw images. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer-kenkremer.com

‘Pinnacle Island’ had suddenly appeared out of nowhere in a set of before/after pictures taken by Opportunity’s cameras on Jan, 8, 2014 (Sol 3540), whereas that exact same spot had been vacant of debris in photos taken barely 4 days earlier. And the rover hadn’t budged a single millimeter.

So the HiRISE research team was called in to plan a new high resolution observation of the ‘Murray Ridge’ area and gather clues about the rocky riddle.

The purpose was to “check the remote possibility that a fresh impact by an object from space might have excavated a crater near Opportunity and thrown this rock to its new location”- now known as Pinnacle Island, said NASA in a statement.

Well, no fresh crater impacting site was found in the new image.

“We see no obvious signs of a very recent crater in our image, but a careful comparison to prior images might reveal subtle changes,” wrote HiRISE principal investigator Alfred McEwen in a description today.

Back on sol 3365 we took this image of Solander Point as we approached it. Here I have plotted the subsequent route that Opportunity has taken in climbing up the ridge. The outcrop shown I the images below are near the end of the yellow traverse line. Caption and mosaic by Larry Crumpler/NASA/JPL/

In the meantime, as I reported here a few days ago the mystery was solved at last by the rover team after Opportunity drove a short distance away from the ‘jelly doughnut’ rock and snapped some ‘look back’ photographs to document the ‘mysterious scene’ for further scrutiny.

It turns out that the six wheeled Opportunity unknowingly ‘created’ the mystery herself when she drove over a larger rock, crushing and breaking it apart with the force from the wheels and her hefty 400 pound (185 kg) mass.

“Once we moved Opportunity a short distance, after inspecting Pinnacle Island, we could see directly uphill an overturned rock that has the same unusual appearance,” said Opportunity Deputy Principal Investigator Ray Arvidson of Washington University in St. Louis, in a NASA statement.

“Murray Ridge” and the Solander Point mountaintop are of great scientific interest because the region is riven with outcrops of minerals, including clay minerals, that likely formed in flowing liquid neutral water conducive to life – potentially a scientific goldmine.

Today, Feb 19, marks Opportunity’s 3582nd Sol or Martian Day roving Mars. She is healthy with plenty of power.

So far she has snapped over 188,800 amazing images on the first overland expedition across the Red Planet.

Her total odometry stands at over 24.07 miles (38.73 kilometers) since touchdown on Jan. 24, 2004 at Meridiani Planum.

Read more about sister Spirit – here and here.

Meanwhile on the opposite side of Mars, Opportunity’s younger sister rover Curiosity is trekking towards gigantic Mount Sharp and just crested over the Dingo Gap sand dune. She celebrated 500 Sols on Mars on New Years Day 2014.

And a pair of new orbiters are streaking to the Red Planet to fortify Earth’s invasion fleet- NASA’s MAVEN and India’s MOM.

Finally, China’s Yutu rover has awoken for her 3rd workday on the Moon.

Stay tuned here for Ken’s continuing Opportunity, Curiosity, Chang’e-3, LADEE, MAVEN, Mars rover, MOM and continuing planetary and human spaceflight news.

Ken Kremer

This image from the panoramic camera (Pancam) on NASA’s rover Opportunity shows the location of a rock called "Pinnacle Island" before it appeared in front of the rover in early January 2014. Arrow at lower left. This image was taken during Sol 3567 of Opportunity's work on Mars (Feb. 4, 2014). Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ. — This image from the panoramic camera (Pancam) on NASA’s rover Opportunity shows the location of a rock called “Pinnacle Island” before it appeared in front of the rover in early January 2014. Arrow at lower left. This image was taken during Sol 3567 of Opportunity’s work on Mars (Feb. 4, 2014). Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

Traverse Map for NASA’s Opportunity rover from 2004 to 2014 This map shows the entire path the rover has driven during a decade on Mars and over 3560 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location by Solander Point summit at the western rim of Endeavour Crater. Rover will spend 6th winter here atop Solander. Opportunity discovered clay minerals at Esperance – indicative of a habitable zone. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer – kenkremer.com — Traverse Map for NASA’s Opportunity rover from 2004 to 2014
This map shows the entire path the rover has driven during a decade on Mars and over 3560 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location by Solander Point summit at the western rim of Endeavour Crater. Rover will spend 6th winter here atop Solander. Opportunity discovered clay minerals at Esperance – indicative of a habitable zone. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer – kenkremer.com

February 19, 2014December 23, 2015 by Jason Major

Stars Boil Before They Blow Up, Says NuSTAR

NASA's NuSTAR is revealing the mechanics behind Cassiopeia A's supernova explosion (Image credit: NASA/JPL-Caltech/CXC/SAO)

Supernovas are some of the most energetic and powerful events in the observable Universe. Briefly outshining entire galaxies, they are the final, dying outbursts of stars several times more massive than our Sun. And while we know supernovas are responsible for creating the heavy elements necessary for everything from planets to people to power tools, scientists have long struggled to determine the mechanics behind the sudden collapse and subsequent explosion of massive stars.

Now, thanks to NASA’s NuSTAR mission, we have our first solid clues to what happens before a star goes “boom.”

The image above shows the supernova remnant Cassiopeia A (or Cas A for short) with NuSTAR data in blue and observations from the Chandra X-ray Observatory in red, green, and yellow. It’s the shockwave left over from the explosion of a star about 15 to 25 times more massive than our Sun over 330 years ago*, and it glows in various wavelengths of light depending on the temperatures and types of elements present.

Artist's concept of NuSTAR in orbit. (NASA/JPL-Caltech) — Artist’s concept of NuSTAR in orbit. (NASA/JPL-Caltech)

Previous observations with Chandra revealed x-ray emissions from expanding shells and filaments of hot iron-rich gas in Cas A, but they couldn’t peer deep enough to get a better idea of what’s inside the structure. It wasn’t until NASA’s Nuclear Spectroscopic Telescope Array — that’s NuSTAR to those in the know — turned its x-ray vision on Cas A that the missing puzzle pieces could be found.

And they’re made of radioactive titanium.

Many models have been made (using millions of hours of supercomputer time) to try to explain core-collapse supernovas. One of the leading ones has the star ripped apart by powerful jets firing from its poles — something that’s associated with even more powerful (but focused) gamma-ray bursts. But it didn’t appear that jets were the cause with Cas A, which doesn’t exhibit elemental remains within its jet structures… and besides, the models relying on jets alone didn’t always result in a full-blown supernova.

As it turns out, the presence of asymmetric clumps of radioactive titanium deep within the shells of Cas A, revealed in high-energy x-rays by NuSTAR, point to a surprisingly different process at play: a “sloshing” of material within the progenitor star that kickstarts a shockwave, ultimately tearing it apart.

Watch an animation of how this process occurs:

The sloshing, which occurs over a time span of a mere couple hundred milliseconds — literally in the blink of an eye — is likened to boiling water on a stove. When the bubbles break through the surface, the steam erupts.

Only in this case the eruption leads to the insanely powerful detonation of an entire star, blasting a shockwave of high-energy particles into the interstellar medium and scattering a periodic tableful of heavy elements into the galaxy.

In the case of Cas A, titanium-44 was ejected, in clumps that echo the shape of the original sloshing asymmetry. NuSTAR was able to image and map the titanium, which glows in x-ray because of its radioactivity (and not because it’s heated by expanding shockwaves, like other lighter elements visible to Chandra.)

“Until we had NuSTAR we couldn’t really see down into the core of the explosion,” said Caltech astronomer Brian Grefenstette during a NASA teleconference on Feb. 19.

Illustration of the pre-supernova star in Cassiopeia A. It's thought that its layers were "turned inside out" just before it detonated. (NASA/CXC/M.Weiss) — Illustration of the pre-supernova star in Cassiopeia A. It’s thought that its layers were “turned inside out” just before it detonated. (NASA/CXC/M.Weiss)

“Previously, it was hard to interpret what was going on in Cas A because the material that we could see only glows in X-rays when it’s heated up. Now that we can see the radioactive material, which glows in X-rays no matter what, we are getting a more complete picture of what was going on at the core of the explosion.”

– Brian Grefenstette, lead author, Caltech

Okay, so great, you say. NASA’s NuSTAR has found the glow of titanium in the leftovers of a blown-up star, Chandra saw some iron, and we know it sloshed and ‘boiled’ a fraction of a second before it exploded. So what?

“Now you should care about this,” said astronomer Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics. “Supernovae make the chemical elements, so if you bought an American car, it wasn’t made in Detroit two years ago; the iron atoms in that steel were manufactured in an ancient supernova explosion that took place five billion years ago. And NuSTAR shows that the titanium that’s in your Uncle Jack’s replacement hip were made in that explosion too.

“We’re all stardust, and NuSTAR is showing us where we came from. Including our replacement parts. So you should care about this… and so should your Uncle Jack.”

And it’s not just core-collapse supernovas that NuSTAR will be able to investigate. Other types of supernovas will be scrutinized too — in the case of SN2014J, a Type Ia that was spotted in M82 in January, even right after they occur.

“We know that those are a type of white dwarf star that detonates,” NuSTAR principal investigator Fiona Harrison responded to Universe Today during the teleconference. “This is very exciting news… NuSTAR has been looking at [SN2014J] for weeks, and we hope to be able to say something about that explosion as well.”

Previous imaging with Chandra (left, middle) is combined with new data from NuSTAR (right) to make a complete image of a supernova remnant. (NASA/JPL-Caltech/CXC/SAO)

One of the most valuable achievements of the recent NuSTAR findings is having a new set of observed constraints to place on future models of core-collapse supernovas… which will help provide answers — and likely new questions — about how stars explode, even hundreds or thousands of years after they do.

“NuSTAR is pioneering science, and you have to expect that when you get new results, it’ll open up as many questions as you answer,” said Kirshner.

Launched in June of 2012, NuSTAR is the first focusing hard X-ray telescope to orbit Earth and the first telescope capable of producing maps of radioactive elements in supernova remnants.

Read more on the JPL news release here, and listen to the full press conference here.

*As Cas A resides 11,000 light-years from Earth, the actual date of the supernova would be about 11,330 years ago. Give or take a few.

February 19, 2014January 13, 2016 by Nancy Atkinson

Kepler’s Universe: More Planets in Our Galaxy Than Stars

Kepler space telescope's field of view. Credit: NASA

Astronomers estimate that the Milky Way contains up to 400 billion stars and thanks to the Kepler mission, we can now estimate that every star in our galaxy has on average 1.6 planets in orbit around it.

This new video from our friends Tony Darnell and Scott Lewis focuses on the discoveries that the Kepler Space Telescope has made, which has opened up a whole new universe and a new way of looking at stars as potential homes for other planets. Only about 20 years ago, we didn’t know if there were any other planets around any other stars besides our own. But now we know we live in a galaxy that contains more planets than stars.

If you extrapolate that number to the rest of the Universe, it’s mind-blowing. According to astronomers, there are probably more than 170 billion galaxies in the observable Universe, stretching out into a region of space 13.8 billion light-years away from us in all directions.

And so, if you multiply the number of stars in our galaxy by the number of galaxies in the Universe, you get approximately 10²⁴ stars. That’s a 1 followed by twenty-four zeros, or a septillion stars.

However, it’s been calculated that the observable Universe is a bubble of space 47 billion years in all directions… or it could be much bigger, possibly infinite. It’s just that we can’t detect those stars because they’re outside the observable Universe.

So, there’s a lot of stars out there.

As the video says, space telescopes give us “a glimpse of our humble place in the cosmic ocean.”

February 19, 2014March 8, 2017 by Fraser Cain

Why Europa?

This artist's rendering shows NASA's Europa mission spacecraft, which is being developed for a launch sometime in the 2020s. This view shows the spacecraft configuration, which could change before launch, as of early 2016. The mission would place a spacecraft in orbit around Jupiter in order to perform a detailed investigation of the giant planet's moon Europa -- a world that shows strong evidence for an ocean of liquid water beneath its icy crust and which could host conditions favorable for life. The highly capable, radiation-tolerant spacecraft would enter into a long, looping orbit around Jupiter to perform repeated close flybys of Europa. Credit: NASA/JPL-Caltech

Forget Mars, the place we really want to go looking for life is Jupiter’s moon Europa. Dr. Mike Brown, a professor of planetary science at Caltech, explains what he finds so fascinating about this icy moon, and the potential we might find life swimming in its vast oceans.
Continue reading “Why Europa?”

February 19, 2014December 23, 2015 by Katrina Cain

Book Review and Giveaway: Women in Space by Karen Bush Gibson

On July 23rd, 2012, Sally Ride died. As the first American woman in space and a true icon of the modern scientific era, her loss was felt all over the world. President Barack Obama said, “Sally was a national hero and a powerful role model. She inspired generations of young girls to reach for the stars.” Ride’s, well, ride into space was wonderfully inspiring, but how many Americans ever read of Kathryn D. Sullivan, Anna Lee Fisher, or the dozens of other American women in space? Outside of space enthusiasts, few people know that the first woman in space was actually a Russian cosmonaut, Valentina Tereshkova, who visited the cosmos nearly 20 years before Ride! While Mae Jemison has reached international fame as a physician and the first African American women in space, few know of the African American women who came after her.

Thanks to our natural, but foolish, inclination to focus on “firsts” and benchmarks as if collecting trivia, it’s elusively easy to believe that these two or three women mentioned in our high-school science texts are the definitive ‘women of space’ and that’s that.

Hardly.

As accomplished author Karen Bush Gibson shows in her latest book, Women in Space: 23 Stories of First Flights, Scientific Missions, and Gravity-Breaking Adventures, space is certainly not an all boy’s club. Throughout the just over 200-page book, Gibson relates the successes and setbacks of nearly two dozen women from ten different countries who made history and forged a path for countless females to follow. Gibson’s book features photographs and nods to access additional learning resources, valuable for any interested reader in showing that this book is truly only just scratching the surface of women’s enormous impact on spaceflight.

Studies seem to pour in almost daily stating that the STEM (Science, Technology, Engineering, Math) fields are increasingly male-dominated, so it’s refreshing to read about the women who overcame the stereotypes and prejudices and dared to go where so few had gone before. Gibson’s book offers an informative, introductory overview of a group of unfortunately under-appreciated heroes – as well as an exhilarating perspective which emphasizes that there is so much more to come.

You can buy a copy of Women in Space from Amazon.com or visit the Chicago Review Press.

Universe Today and Chicago Review Press are pleased to be able to offer two free copies of Women in Space to our readers. In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Wednesday. February 26. If this is the first time you’re registering for a giveaway, you’ll receive a confirmation email immediately where you’ll need to click a link to be entered into the drawing. For those who have registered previously, you’ll receive an email later where you can enter this drawing.

February 19, 2014December 23, 2015 by Shannon Hall

Is Eta Carinae Heading Toward Another Eruption?

Massive stars can devastate their surroundings, unleashing hot winds and blasting radiation. With a mass over 100 times heavier than the Sun and a luminosity a million times brighter than the Sun, Eta Carinae clocks in as one of the biggest and brightest stars in our galaxy.

The enigmatic object walks a thin line between stellar stability and tumultuous explosions. But now a team of international astronomers is growing concerned that it’s leaning toward instability and eruption.

In the 19th Century the star mysteriously threw off unusually bright light for two decades in an event that became known as the “Great Eruption,” the causes of which are still up for debate. John Herschel and others watched as Eta Carinae’s brightness oscillated around that of Vega — rivaling a supernova explosion.

We now know the star ejected material in the form of two big globes. “During the eruption the star threw off more than 10 solar masses, which can now be observed as the surrounding bipolar nebula,” said lead author Dr. Andrea Mehner from the European Southern Observatory. Miraculously the star survived, but the nebula has been expanding into space ever since.

Eta Carinae has been observed at the South African Astronomical Observatory — a 0.75m telescope outside of Cape Town — for more than 40 years, providing a wealth of data. From the start of observations in 1976 until 1998, astronomers saw an increase across the J, H, K and L bands — filters, which allow certain wavelength ranges of infrared light to pass through.

“This data set is unique for its consistency over a timespan of more than 40 years,” Mehner told Universe Today. “It provides us with the opportunity to analyze long-term changes in the system as Eta Carinae still recovers from its Great Eruption.”

In order to understand the longterm overall increase in light we have to look at a more recent discovery noted in 2005 when scientists discovered that Eta Carinae is actually two stars: a massive blue star and a smaller companion. The temperature increased for 15 years until the companion came very close to the massive star, reaching periastron.

This increase in brightness is likely due to an overall increase in temperature of some component of the Eta Carinae system (which includes the massive blue star, its smaller companion, and the shells of gas and dust that now enshroud the system).

After 1998, however, the linear trend changed significantly and the star’s brightness increased much more rapidly in the J and H bands. It’s getting bluer, which in astronomy, typically means it’s getting hotter.

However, it’s unlikely the star itself is getting hotter. Instead we are seeing the effect of dust around the star being destroyed rapidly. Dust absorbs blue light. So if the dust is getting destroyed, more blue light will be able to pass through the nebulous globes surrounding the system. If this is the case, then we’re really seeing the star as it truly is, without dust absorbing certain wavelengths of its light.

While the nebula is slowly expanding and the dust is therefore dissipating, the authors do not think it’s enough to account for the recent brightening. Instead Eta Carinae is likely rotating at a different speed or losing mass at a different rate. “The changes observed may imply that the star is becoming more unstable and may head towards another eruptive phase,” Mehner told Universe Today.

Perhaps Eta Carinae is heading toward another “Great Eruption.” Only time will tell. But in a field where most events occur on a timescale of millions of years, it’s a great opportunity to watch the system evolve on a human time scale. And when Eta Carinae reaches periastron in the middle of this year, tens of telescopes will be collecting its light, hoping to see a sudden turn of events that may help us explain this exotic system.

The paper has been accepted for publication in Astronomy & Astrophysics and is available for download here.