The globular cluster NGC 6388. Blue stragglers may clearly be seen around the edges. More are hidden within the central core. Credit: ESO
A unique and enigmatic variety of stars known as blue stragglers appear to defy the normal stellar aging process. Discovered in globular clusters, they appear much younger than the rest of the stellar population. Since their discovery in 1953, astronomers have been asking the question: how do these stars regain their youth?
For years, two theories have persisted. The first theory suggests that two stars collide, forming a single more massive star. The second theory proposes that blue stragglers emerge from binary pairs. As the more massive star evolves and expands, it blows material onto the smaller star. In both theories, the star grows steadily more massive and bluer – it regains its youth.
But now, a surprising finding may lend credence to the second theory. Astronomers at the Nicolaus Copernicus Astronomical Center in Poland recently observed a blue straggler caught in the midst of forming!
The binary system that was studied, known as M55-V60, is located within the globular cluster M55. Dr. Michal Rozyczka, one of the research scientists on the project, told Universe Today, “The system is a showcase example of a blue straggler formed via the theoretically predicted peaceful mass exchange between its components.”
The team used both photometric (the overall light from the system) and spectroscopic (the light spread out into a range of wavelengths) observations. The photometric data revealed the light curve – the change in brightness due to one star passing in front of the other – of the system. This provided evidence that the astronomers were looking at a binary system.
From the spectroscopic data, shifts in wavelength reveal the velocity (along the line of sight) of a source. The research team noted that the system’s center of mass was moving with respect to the binary system. This will occur in a semi-detached binary system, where mass transfers from one star to the other. As it does this, the center of mass will follow the mass-transfer.
From both photometric and spectroscopic observations (which covered more than 10 years!) the team was able to verify that this object is not only a binary, but a semi-detached binary, residing at the edge of M55.
An artist’s conception of how a blue straggler may form from a binary system. Credit: NASA/ESA
“The system is semi-detached with the less massive (secondary) component filling its Roche lobe,” explained Dr. Rozyczka. “The secondary has a tearlike shape, with the tip of the tear directed toward the more massive primary. A stream of gas flows out of the tip along a curved path and hits the primary.”
How do we know that it is in fact a blue straggler? The simple answer is that the secondary star, with is gaining mass, appears bluer than normal. This blue straggler is clearly in the process of forming. It is the second observation of such a formation, with the first being V228 in the globular cluster: 47 Tuc.
This research verifies that semi-detached binaries are a viable formation mechanism for blue stragglers. The binary was discovered by happenstance, in a project aimed at determining accurate ages and distances of nearby clusters. It’s certainly a surprising result from the survey.
The results will be published in Acta Astronomica, a peer-reviewed scientific journal located in Poland (preprint available here).
Several types of downhill flow features have been observed on Mars. This image from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter is an example of a type called "linear gullies." Image credit: NASA/JPL-Caltech/Univ. of Arizona
Extreme sports taking on place on Mars? How about snowboarding – or actually sandboarding –down Martian dunes on a cushion of carbon dioxide? Sounds fun, and this might be happening already – sans the humanoid snowboarders, however.
Scientists have been wondering what caused unusual hillside grooves on Mars, called linear gullies. New research and test runs down sand dunes here on Earth has shown that these gullies may be formed by chunks of frozen carbon dioxide sliding down some Martian sand dunes on cushions of gas. They are plowing furrows as they slide, and creating open pits at the bottom of the run.
And these are not the Martian Sand Skimmers of Martian Chronicles fame. Just chunks of dry ice going for a joy ride.
“I have always dreamed of going to Mars,” said Serina Diniega, a planetary scientist at NASA’s Jet Propulsion Laboratory and lead author of a report published online by the journal Icarus. “Now I dream of snowboarding down a Martian sand dune on a block of dry ice.”
In images from the Mars Reconnaissance Orbiter’s HiRISE (High Resolution Imaging Science Experiment) camera the linear gullies seem to all have relatively constant width — up to a few yards, or meters, across — with raised banks or levees along the sides. Unlike gullies caused by water flows on Earth and possibly on Mars, they do not have aprons of debris at the downhill end of the gully. Instead, many have pits at the downhill end.
“In debris flows, you have water carrying sediment downhill, and the material eroded from the top is carried to the bottom and deposited as a fan-shaped apron,” said Diniega. “In the linear gullies, you’re not transporting material. You’re carving out a groove, pushing material to the sides.”
HiRISE images show the sand dunes with linear gullies covered by carbon-dioxide frost during the Martian winter. The location of the linear gullies is on dunes that spend the Martian winter covered by carbon-dioxide frost. By comparing before-and-after images from different seasons, researchers determined that the grooves are formed during early spring. Some images have even caught bright objects in the gullies.
Diniega and her team theorize the bright objects are pieces of dry ice that have broken away from points higher on the slope. According to the new hypothesis, the pits could result from the blocks of dry ice completely sublimating away into carbon-dioxide gas after they have stopped traveling.
“Linear gullies don’t look like gullies on Earth or other gullies on Mars, and this process wouldn’t happen on Earth,” said Diniega. “You don’t get blocks of dry ice on Earth unless you go buy them.”
Co-author on the paper Candice Hansen, of the Planetary Science Institute suspected that dry ice might be involved in forming these linear gullies, so like any good planetary scientist she bought some slabs of dry ice at a supermarket and slid them down sand dunes.
And voilà, similar looking linear gullies with the gaseous carbon dioxide from the thawing ice maintaining a lubricating layer under the slab. As the chunk slide down the dune, it also pushed sand aside into small levees. Handsen said the slabs glided down even low-angle slopes, not much pushing required.
Of course, the team said, the outdoor tests did not simulate Martian temperature and pressure, but calculations indicate the dry ice would act similarly in early Martian spring where the linear gullies form. Although water ice, too, can sublimate directly to gas under some Martian conditions, it would stay frozen at the temperatures at which these gullies form, the researchers calculate.
“MRO is showing that Mars is a very active planet,” Hansen said. “Some of the processes we see on Mars are like processes on Earth, but this one is in the category of uniquely Martian.”
Hansen also noted the process could be unique to the linear gullies etched on Martian sand dunes.
“There are a variety of different types of features on Mars that sometimes get lumped together as ‘gullies,’ but they are formed by different processes,” she said. “Just because this dry-ice hypothesis looks like a good explanation for one type doesn’t mean it applies to others.”
Harrumph. Dry ice having fun on Mars fun without us.
The Sculptor galaxy is seen in a new light, in this composite image from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Southern Observatory in Chile. Image credit: NASA/JPL-Caltech/JHU
The Chandra X-ray Observatory has been keeping an eye on a black hole actively munching away on gas at the middle of the nearby Sculptor galaxy. Now, with the added eyes of the Nuclear Spectroscopic Telescope Array (NuSTAR), which sees higher-energy X-ray light, the observatories have found the black hole has fallen asleep, even amid rampant star-formation going on around it.
“Our results imply that the black hole went dormant in the past 10 years,” said Bret Lehmer of the Johns Hopkins University, Baltimore, and NASA’s Goddard Space Flight Center. “Periodic observations with both Chandra and NuSTAR should tell us unambiguously if the black hole wakes up again. If this happens in the next few years, we hope to be watching.”
Lehmer is lead author of a new study detailing the findings in the Astrophysical Journal.
The now-latent black hole is about 5 million times the mass of our Sun. The Sculptor galaxy (NGC 253) is a so-called starburst galaxy, which is actively giving birth to new stars. At just 13 million light-years away, it is one of the closest starbursts galaxies to us.
Why did the black hole go dormant?
“Black holes feed off surrounding accretion disks of material. When they run out of this fuel, they go dormant,” said co-author Ann Hornschemeier of Goddard. “NGC 253 is somewhat unusual because the giant black hole is asleep in the midst of tremendous star-forming activity all around it.”
“Black hole growth and star formation often go hand-in-hand in distant galaxies,” added Daniel Stern, a co-author and NuSTAR project scientist at the Jet Propulsion Laborator. “It’s a bit surprising as to what’s going on here, but we’ve got two powerful complementary X-ray telescopes on the case.”
Chandra first observed signs of what appeared to be a feeding supermassive black hole at the heart of the Sculptor galaxy in 2003. Then, in September and November of 2012, Chandra and NuSTAR observed the same region simultaneously. NuSTAR, which launched in June of 2012, detected focused, high-energy X-ray light from the region, allowing the researchers to say conclusively that the black hole is not accreting material.
There are two possibilities: either the black hole has in fact gone dormant, or another possibility is that the black hole was not actually awake 10 years ago, and Chandra observed a different source of X-rays. Future observations with both telescopes may solve the puzzle.
The combination of coordinated Chandra and NuSTAR observations is extremely powerful for answering questions like this,” said Lou Kaluzienski, NuSTAR Program Scientist at NASA Headquarters in Washington. “Now, we can get all sides of the story.”
NuSTAR launched into space in June of 2012.
If and when the Sculptor’s slumbering giant does wake up in the next few years amidst all the commotion, NuSTAR and Chandra will monitor the situation. The team plans to check back on the system periodically.
Falcon 9-R 112-second test fire. Via SpaceX/YouTube.
Last week, SpaceX fired up a new version of the Falcon 9 for a short 10-second test fire. Now, they’ve completed a long-duration fire, lasting 112 seconds. The test was of the first stage of the F9-R, an advanced prototype for the world’s first reusable rocket. The test took place at SpaceX’s rocket development facility in McGregor, Texas. SpaceX noted that unlike airplanes, a rocket’s thrust increases with altitude, and the F9-R generates just over a million pounds of thrust at sea level (“enough to lift skyscraper,” SpaceX CEO Elon Musk said via Twitter) but gets up to 1.5 million pounds of thrust in the vacuum of space.
The rocket engines used on the test is the same as what’s used on the Grasshopper, which is the 10-story Vertical Takeoff Vertical Landing (VTVL) vehicle that SpaceX has designed to test the technologies needed to return a rocket back to Earth intact. While the Grasshopper uses just one Merlin 1D engine, the Falcon 9-R uses nine.
SpaceX hasn’t posted any details about the 9-R on their website, but they have said the Merlin 1-D’s 150:1 thrust-to-weight ratio would be the highest ever achieved for a rocket engine.
Shenzhou 10, atop the Long March 2F/Y10 rocket, en route to the launch pad in early June. Credit: CMSE.gov.cn
Riding atop a fiery Long March rocket, three taikonauts blasted off from Earth today (June 11) to kick off an expected 15-day mission in space that will include the first Chinese “space class” from orbit.
Shenzhou 10 departed the Jiuquan Satellite Launch Center at 5:38 a.m. EDT (9:38 a.m. UTC), or 5:38 p.m. local time at the complex’s location in the Gobi desert. Aboard the spacecraft were one woman (Wang Yaping) and two men (Nie Haisheng and Zhang Xiaoguang). Their next destination is the Chinese Tiangong-1 station.
China has a young manned space program. The first spaceflight with people was just a decade ago, in October 2003, and this is the fifth crewed mission since that time.
While China’s government keeps its long-term ambitions fairly private, observers in the United States and China point to its robotic moon missions as evidence that China is considering a manned lunar mission in the coming decades.
Shenzhou 10’s ultimate destination, however, is the Earth-orbiting, nine-ton Tiangong-1. Like the early U.S. and Soviet space stations, the Chinese one is fairly small (a single module) and serves as an experimental testbed for space station work. Taikonauts also visited the space station during Shenzhou 9 in 2012.
– Launch crew and cargo aboard Shenzhou 10 and verify rendezvous and docking technology for the meeting with Tiangong-1;
– Further test Tiangong-1’s capabilities to support humans;
The Shenzhou 10 spacecraft and Long March 2F/Y10 carrier rocket at the launchpad in early June 2013. Credit: China Manned Space Engineering
– Conduct several experiments (focusing on space adaptability, space operation ergonomics and unspecified space science work), perform maintenance and do a “space class” with students;
– To see how well the CMSE is performing on a systems basis.
“To further improve the safety, reliability and to be suitable for the specific requirements of this mission,” stated spokesperson Wu Ping, “partial technical alterations have been made in [the] Shenzhou 10 spaceship and Long March 2F Y10 rocket.
“During this mission,” she added, “taikonauts will change and repair some of the equipment and facilities in Tiangong-1 through on-orbit operations.”
In the first few hours after launch, the CMSE stated that all systems are performing normally.
“The Shenzhou 10 spaceship has accurately entered its orbit and the crew members [are] in good condition,” stated Zhang Youxia, chief commander of China’s manned space program.
The mission drew praise from China’s president, Xi Jinping, who sent the crew good wishes just before they left Earth.
An artist’s rendering of the Tiangong-1 module, China’s space station, which was launched to space in September, 2011. To the right is a Shenzhou spacecraft, preparing to dock with the module. Image Credit: CNSA
“You have made Chinese people feel proud of ourselves,” Xi told the crew, according to a BBC report.
“You have trained and prepared yourselves carefully and thoroughly, so I am confident in your completing the mission successfully. I wish you success and look forward to your triumphant return.”
China ultimately plans to launch a larger space station sometime around 2020, which would include several modules.
The European Space Agency is considering working more closely with China around that time, the BBC added, and some astronauts have already starting Chinese language training.
Waxing Crescent Moon with Mercury and Venus forming a beautiful celestial triangle. Shot at the Municipal Airport in Castroville, Texas, USA. Credit and copyright: Adrian New.
Last night (June 10, 2013) the two innermost worlds of our Solar System visible were joined by a very slender waxing crescent Moon, just over two days after New phase (see our preview of the event here). Several of our readers managed to capture this beautiful twilight triple conjunction. Our lead image is from Adrian New, who went to the Municipal Airport in Castroville, Texas to view the conjunction. “There was a rotating beacon light that would illuminate the planes wing tips at intervals, so I would wait to trip the shutter to capture the effect,” New said via email. This image was taken with a Nikon D800 and a 24-70mm F/2.8 lens set at 70mm @ ISO 2000 and a 1/2 second exposure.
Venus (low) and Mercury (high) were joined by a beautiful 4% dark-orange colored slice of Moon, with clouds adding a bit of drama in the skies over the Sulmona, Abruzzo region of Italy. Credit and copyright: Giuseppe Petricca.
Giuseppe Petricca from the Tuscany region of Italy said he felt lucky to manage to photograph the conjunction, “because the clouds were ‘a bit’ in the way, but also contributed positively to give a nice frame to the whole conjunction.” Giuseppe used a Nikon P90 Bridge digital camera, ISO 100, f5.6, 1/3″. Processed later with Photoshop to increase contrast to enhance the two planets in the sky.
4% Crescent Moon, Mercury, and Venus seen from Lost Mountain, Georgia, USA. Credit and copyright: Stephen Rahn.The Moon joined Venus and Mercury in the clear sky near Salem, Missouri, USA. Credit and copyright: Joe Schuster, Lake County Astronomical Society.The crescent Moon forms a triangle with Venus and Mercury. Taken near Las Vegas on June 10, 2013. Credit and copyright: John Lybrand.The view of Venus, Mercury and the Moon from Ankara, Turkey on June 11, 2013, 21:10 UTC. Credit and copyright: Yuksel Kenaroglu (Canon A40.0, ISO: 50)
Just a reminder to keep looking at sunset for the elusive planet Mercury. As UT writer David Dickinson said in his preview article, if you’ve never seen Mercury, this week is a great time to try.
Long-exposure Cassini NAC image of Saturn's D ring system (NASA/JPL-Caltech/SSI)
The closest to the planet itself, the hazy arcs of Saturn’s D ring may lack the reflective brilliance and sharply-defined edges of the other main rings, but they nevertheless possess their own ethereal beauty and mysteries. Here, the Cassini spacecraft has managed to capture the soft bands of the D ring in a long-exposure image acquired on April 2, 2013 — so long an exposure, in fact, that background stars seen through the rings appear as long vertical streaks, a testament to the ring’s dimness as well as the spacecraft’s continuing movement.
Beginning 8,768 km (5,448 miles) above the tops of Saturn’s clouds, the D ring is the innermost and thinnest segment of Saturn’s main ring system. Nearly transparent, the D ring extends about 7,500 km (4,660 miles) before transitioning to the considerably brighter C ring, which is over twice as wide.
The innermost portion of the C ring can be seen above along the left side. Saturn’s shadow blankets the lower right corner.
The cause of the alternating light-and-dark bands observed within the D ring isn’t yet known, but they may be the result of an impact by a comet or large meteor that set up recurring waves of material.
The view was acquired at a distance of approximately 510,000 kilometers (317,000 miles) from Saturn and at a phase angle of 147 degrees. Image scale is 2 miles (3 kilometers) per pixel.
Opportunity captures a panoramic view of the road ahead to the raised rim of Solander Point (at left) which is some 0.8 mile (1.3 km) away. Arrival is targeted for August. It features a thick strata of ancient rocks which may harbor clay minerals indicative of a habitable zone and northerly tilted slopes to maximize power generation from the solar panels during upcoming 6th winter season at Endeavour crater rim. This navcam photo mosaic was taken on Sol 3330, June 6, 2013. Credit: NASA/JPL/Cornell//Marco Di Lorenzo/Ken Kremer (kenkremer.com)
On the cusp of the 10th anniversary since launching to the Red Planet, NASA’s long lived Opportunity rover has discovered a habitable zone on Mars that once coursed with ‘drinkable water’ and possesses the chemical ingredients necessary to support a path to potential Martian microbes.
At a rock called “Esperance”, Opportunity found a cache of phyllosilicate clay minerals that typically form in neutral, drinkable water that is not extremely acidic or basic.
The finding ranks as “One of my personal Top 5 discoveries of the mission,” said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for NASA’s rover mission at a media briefing.
And despite her advancing age Opportunity remains healthy after surviving in excess of an incredible 3333 Sols, or days, trekking across the alien and ever harsh Martian crater plains.
Furthermore the intrepid robot just sat sail on a southerly course for a new destination called “Solander Point” where researches hope to find more even evidence of habitable environments since they already spotted deeper stakes of ancient rocks transformed by water eons ago. See our current photo mosaics showing Solander Point as Opportunity roves across the crater floor – above and below by Marco Di Lorenzo and Ken Kremer.
After weeks of trying, the rover deployed the robotic arm to drill at a sweet spot inside “Esperance” and collected convincing X-Ray spectroscopic data in the area she just investigated in May 2013 around the eroded rim of giant Endeavour Crater.
“Esperance is rich in clay minerals and shows powerful evidence of water alteration,” Squyres elaborated.
“This is the most powerful evidence we found for neutral pH water.”
“Clay minerals only tend to form at a more neutral pH. This is water you could drink,” Squyres gushed.
These finding represent the most favorable conditions for biology that Opportunity has yet seen in the rock histories it has encountered after nearly a decade roving the Red Planet.
“This is water that was much more favorable for things like pre-biotic chemistry – the kind of chemistry that could lead to the origin of life,” Squyres stated.
Opportunity snapped this color view of ‘Solander Point’ on June 1, 2013 (Sol 3325) looking south to her next destination which she should reach in August. The solar powered robot will spend the upcoming 6th winter season on northerly tilted slopes exploring the thick strata of ancient rocks. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
Esperance is unlike any rock previously investigated by Opportunity; rich in aluminum, which is strongly indicative of clay minerals, perhaps like montmorillonite.
Most rocks inspected to date by Opportunity were formed in an environment of highly acidic water that is extremely harsh to most life forms.
“If you look at all of the water-related discoveries that have been made by Opportunity, the vast majority of them point to water that was a very low pH – it was acid,” Squyres explained.
Esperance was found on ‘Cape York’, a hilly segment of the western rim of Endeavour crater which spans 14 miles (22 km) across. The robot arrived at the edge of Endeavour crater in mid-2011 and will spend her remaining life driving around the scientifically rich crater rim segments.
The pale rock in the upper center of this image, about the size of a human forearm, includes a target called “Esperance,” which was inspected by NASA’s Mars Exploration Rover Opportunity. Data from the rover’s alpha particle X-ray spectrometer (APXS) indicate that Esperance’s composition is higher in aluminum and silica, and lower in calcium and iron, than other rocks Opportunity has examined in more than nine years on Mars. Preliminary interpretation points to clay mineral content due to intensive alteration by water. Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ
NASA’s new Curiosity rover also recently discovered clay minerals and a habitable environment at Gale Crater – on the other side of Mars – stemming from a time when Mars was warmer and wetter billions of years ago.
Over time Mars became the cold and dry place it is today. Scientists hope the rovers provide clues to Mars dramatic transformation.
The solar powered rover is now driving as quick as possible to reach the northerly tilled slopes of ‘Solander Point’ in August, before the onset of the next Martian winter.
‘Solander Point’ offers a much taller stack of geological layering than ‘Cape York.’ Both areas are raised segments of the western rim of Endeavour Crater.
“There’s a lot to explore there. In effect, it’s a whole new mission,” said Ray Arvidson, the mission’s deputy principal scientific investigator from Washington University in St. Louis, Mo.
‘Esperance’ Target Examined by Opportunity in May 2013. The pale rock called “Esperance,” has a high concentration of clay minerals formed in near neutral water indcating a spot favorable for life. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
Opportunity and her twin “Spirit” were launched to Mars on planned 90 day missions.
Both rovers have far exceeded everyone’s wildest expectations. Spirit endured more than 6 years inside Gusev Crater until succumbing to the bone chilling Martian winter in 2011.
NASA’s Opportunity Mars rover discovered clay minerals at Cape York ridge along the rim of Endeavour crater – seen in this photo mosaic – which stands as the most favorable location for Martian biology discovered during her entire nearly 10 year long mission to Mars. Opportunity also established a new American driving record for a vehicle on another world on May 15, 2013 (Sol 3309) and made history by driving ahead from this point at Cape York. This navcam photo mosaic shows the view forward to her next destinations of Solander Point and Cape Tribulation along the lengthy rim of huge Endeavour crater spanning 14 miles (22 km) in diameter.
Credit: NASA/JPL/Cornell/Ken Kremer (kenkremer.com)/Marco Di Lorenzo
Opportunity has lasted more than 37 times beyond the three month “warranty”.
“This is like your car not lasting 200,000 miles, or even a million miles. You’re talking about a car that lasts 2 million miles without an oil change,” Callas said. “At this point, how long Opportunity lasts is anyone’s guess.”
“Remember, the rover continues to operate in a very hostile environment, where we have extreme temperature changes every day, and the rover could have a catastrophic failure at anytime,” said John Callas, of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., project manager for the Mars Exploration Rover Project.
“So every day is a gift.”
And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013
June 23: “Send your Name to Mars on MAVEN” and “CIBER Astro Sat, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM
Opportunity captures the eerie Martian scenery looking south across Botany Bay from the southern tip of Cape York to her next destination – Solander Point, about 1 mile (1.6 km) away. This navcam photo mosaic was taken on Sol 3317, May 23, 2013. Credit: NASA/JPL/Cornell//Marco Di Lorenzo/Ken Kremer (kenkremer.com)Traverse Map for NASA’s Opportunity rover from 2004 to 2013.
This map shows the entire path the rover has driven during more than 9 years and over 3330 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location heading south to Solander Point from Cape York ridge at the western rim of Endeavour Crater.
Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer
This article comes from our archive, but we updated it with this video.
Saturn is my absolute favorite object in the night sky. When I was a child, I had a dog-eared book on the Solar System, which I read over and over, stopping and staring with wonder at the section on Saturn. How could a planet have rings of ice? What would it be like to fly out and visit the planet, to see the rings with your own eyes. How did it get all those strange moons?
When I was 14, I purchased my first telescope, a 4-inch Newtonian from a local company in Vancouver. It was summer, and one of the first planets, appearing just after sunset was Saturn. And my telescope had just enough power and magnification to resolve the planet and its famous rings. In fact, when I first looked at Saturn through the eyepiece, I couldn’t believe that I was now seeing the planet with my own eyes. It didn’t look quite like the photographs, but my imagination could fill in the gaps.
From those first observations, my fascination with astronomy and Saturn only grew, leading me to a career in science journalism. It’s funny to think how far I’ve come, and how I can trace everything back to those warm summer nights, looking at Saturn.
Think you know everything about Saturn? Think again. Here are 10 facts about Saturn, some you may know, and some you probably didn’t know.
1. Saturn is the least dense planet in the Solar System
Saturn has a density of 0.687 grams/cubic centimeter. Just for comparison, water is 1 g/cm3 and the Earth is 5.52. Since Saturn is less dense than water, it would actually float like an apple if you could find a pool large enough. Of course, why you’d want to ruin a pool with all that hydrogen, helium and ices…
2. Saturn is a flattened ball
Saturn spins so quickly on its axis that the planet flattens itself out into an oblate spheroid. Seriously, you see this by eye when you look at a picture of Saturn; it looks like someone squished the planet a little. Of course, it’s the rapid spinning that’s squishing it, causing the equator to bulge out.
While the distance from the center to the poles is 54,000 km, the distance from the center to the equator is 60,300 km. In other words, locations on the equator are approximately 6,300 km more distant from the center than the poles.
We have a similar phenomenon here on Earth, where points on the equator are more distant from the center of the Earth, but on Saturn, it’s much more extreme.
Cassini’s drawings of Saturn
3. The first astronomers thought the rings were moons.
When Galileo first turned his rudimentary telescope on Saturn in 1610, he could see Saturn and its rings, but he didn’t know what he was looking at. He though that the rings might actually be two large moons stuck to either side of Saturn – ears maybe?
It wasn’t until 1655 that the Dutch astronomer Christian Huygens used a better telescope to observe Saturn. He had the resolution to realize that the moons on either side of Saturn were actually rings: “a thin, flat ring, nowhere touching, and inclined to the ecliptic.” Huygens was also the first person to discover Saturn’s largest moon, Titan.
Voyager 2. Credit: NASA
4. Saturn has only been visited 4 times by spacecraft
Only 4 spacecraft sent from Earth have ever visited Saturn, and three of these were just brief flybys. The first was Pioneer 11, in 1979, which flew within 20,000 km of Saturn. Next came Voyager 1 in 1980, and then Voyager 2 in 1981. It wasn’t until Cassini’s arrival in 2004 that a spacecraft actually went into orbit around Saturn and captured photographs of the planet and its rings and moons.
Unfortunately, there are no future plans to send any more spacecraft to Saturn. A few missions have been proposed, including such radical concepts as a sailboat that could traverse the liquid methane lakes on Titan.
5. Saturn has 62 moons
Jupiter has 67 discovered moons, but Saturn is a close second with 62. Some of these are large, like Titan, the second largest moon in the Solar System. But most are tiny – just a few km across, and they have no official names. In fact, the last few were discovered by NASA’s Cassini orbiter just a few years ago. More will probably be discovered in the coming years.
6. The length of a day on Saturn was a mystery until recently
Determining the rotation speed of Saturn was actually very difficult to do, because the planet doesn’t have a solid surface. Unlike Mercury, you can’t just watch to see how long it takes for a specific crater to rotate back into view; astronomers needed to come up with a clever solution: the magnetic field.
To determine the rotational speed of Saturn, astronomers had to measure the rotation of the planet’s magnetic field. By one measurement, Saturn takes 10 hours and 14 minutes to turn on its orbit, but when Cassini approached Saturn, it clocked the rotation at 10 hours and 45 minutes. Astronomers now agree on an average day of 10 hours, 32 minutes and 35 seconds.
Saturn. NASA/JPL/Caltech
7. Saturn’s rings could be old, or they could be young.
It’s possible that Saturn’s rings have been around since the beginning of the Solar System – around 4.54 billion years ago. Or maybe they’re relatively brand new compared to the age of Saturn. Astronomers still don’t fully understand the origin of Saturn’s rings.
They might have formed recently, when a 300-km ice moon was torn apart by Saturn’s gravity, forming a ring around the planet.
It’s also possible that they’re the left over material when Saturn formed in the solar nebula. The material in the rings might have gotten jostled by Saturn’s gravity, and never could pull together into a cohesive Moon.
But astronomers have also found that the ring material looks just too clean to have formed so long ago, and could be as young as 100 million years old. It’s all just a big mystery.
Credit: NASA/JPL-Caltech/Space Science Institute
8. Sometimes the rings disappear
Well, they don’t actually disappear, but they look like they’re going away. Saturn’s axis is tilted, just like Earth. From our point of view, we see Saturn’s changing position as it takes its 30 year journey around the Sun. Sometimes, the rings are fully open, and we see them in all their glory, but other times we see the rings edge on – it looks like they’ve disappeared. This happened in 2008-2009, and will happen again in 2024-2025.
9. You can see Saturn with your own eyes
Saturn appears as one of the 5 planets visible with the unaided eye. If Saturn is in the sky at night, you can head outside and see it. To see the rings and the ball of the planet itself, you’ll want to peer through a telescope. But you can amaze your friends and family by pointing out that bright star in the sky, and let them know they’re looking at Saturn.
10. There could be life near Saturn
Not life on Saturn; the planet is way too hostile to support life. But there could be life on one of Saturn’s moons: Enceladus.
Water vapour geysers on Enceladus. Credit: NASA/JPL
NASA’s Cassini spacecraft recently discovered ice geysers blasting out of Enceladus’ southern pole. This means that some process is keep the moon warm enough that water can remain a liquid underneath the surface. And wherever we find liquid water on Earth, we find life.
Canadian Space Agency employees welcomed astronaut Chris Hadfield as he walked in the building. Credit: Canadian Space Agency.
In a somewhat surprise announcement, Canadian astronaut — and social media icon — Chris Hadfield announced his retirement from the astronaut corps, just weeks after he returned home from his highly successful expedition to the International Space Station.
The wildly popular Hadfield made the announcement at the Canadian Space Agency headquarters near Montreal on Monday. He had called a press conference there to share highlights from his five-month mission, but also announced his retirement as well as his plans to return to live in Canada after spending much of his 21-year astronaut career at Johnson Space Center in Houston or Star City in Russia.
“I’m making good on a promise I made my wife nearly 30 years ago — that yes, eventually, we would be moving back to Canada,” Hadfield said during the press conference.
In posting the above image on Twitter, he said that saying “goodbye to these good people today was much harder than I expected.”
The 53-year-old Hadfield sent a nearly constant stream of magnificent images, informative videos and ebullient Tweets during his pre-flight training and his Expedition 34/35, as well as hosting numerous interviews and educational events with school groups via webcasts from the ISS. With over a million followers on Twitter, his words were read – and widely retweeted — by people around the world.
“I am extremely proud to have shared my experience,” Hadfield said in a statement from the CSA. “I will continue to reinforce the importance of space exploration through public speaking and will continue to visit Canadian schools through the CSA.”
“Chris Hadfield made space exploration history by becoming the first Canadian to command the International Space Station, a feat that instilled pride from coast-to-coast-to-coast,” said Candian Parliamentary Secretary Chris Alexander. “His efforts have affirmed our country’s world-renowned space expertise. I would like to personally thank Chris for his commitment to bringing the spirit of discovery not only to all Canadians, but to the world.”
