Space Observatories Watch a Black Hole Go Dormant

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.

Source: JPL

SpaceX Fires Up Falcon 9-R in a Long Duration Test

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.

‘Space Class’ Among Aims of Chinese Taikonauts Who Left Earth Today

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.

The taikonauts have four main ambitions during the Shenzhou 10 mission, the China Manned Space Engineering government office stated:

– 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
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
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.

Astrophotos: Crescent Moon, Mercury and Venus Together in the Sky

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.
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.
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 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 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)
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.

Cassini Captures Saturn’s Darkest Rings

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.

Source: NASA/JPL Cassini mission site.

Opportunity Rover Discovers Martian Habitable Zone Favorable for Pre-biotic Chemistry

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.
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
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.
‘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.

Opportunity 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 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.  Opportunity discovered clay minerals at Cape York and stands as the most favorable location for Martian biology discovered during her entire nearly 10 year long mission to Mars.  Credit: NASA/JPL/Cornell/Kenneth Kremer/Marco Di Lorenzo
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

Ken Kremer

…………….
Learn more about Mars, Curiosity, Opportunity, MAVEN, LADEE, CIBER, Conjunctions and NASA missions at Ken’s upcoming lecture presentations

June 11: “Send your Name to Mars on MAVEN” and “LADEE Lunar & Antares Rocket Launches from Virginia”; NJ State Museum Planetarium and Amateur Astronomers Association of Princeton (AAAP), Trenton, NJ, 730 PM.

June 12: “Send your Name to Mars on MAVEN” and “LADEE Lunar & Antares Rocket Launches from Virginia”; Franklin Institute and Rittenhouse Astronomical Society, Philadelphia, PA, 8 PM.

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)
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
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

Ten Interesting Facts About Saturn

Interesting Facts About Saturn
Interesting Facts About Saturn

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
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
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
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
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
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.

Want to learn more about Saturn?

We’ve recorded two episodes of Astronomy Cast just about Saturn. The first is Episode 59: Saturn, and the second is Episode 61: Saturn’s Moons.

Chris Hadfield Hangs Up His Astronaut Suit

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.”

Sources: CSA press release, CBC

Stunning Astrophoto: The Milky Way Seen in ‘Daylight’

A rocky region of Portinho da Arrábida, Portugal, with the center of Milky Way behind it, visible at dawn. Credit and copyright: Miguel Claro

Ever seen the arc of the Milky Way in daylight? Astrophotographer Miguel Claro came as close as possible by capturing this view of ‘Via Lactea’ at dawn on May 11, 2013, with the stars of Saggitarius and Scorpius clearly visible, while the sky is slowly turning blue. The image was taken with a rocky region of the resort area of Portinho da Arrábida, in Portugal, visible in the foreground. Also visible is the Red Supergiant star Antares.

See Claro’s website for an annotated version of this image that identifies the various features.

Miguel used a Canon 60Da – ISO 1600; Exp.15 Sec; f/2.8; 24mm. The image was taken on May 11, 2013 at 5:14 AM local time.

What a great way to start the day!

Thanks to Miguel Claro for sharing his images.

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An Early Start for Noctilucent Clouds

Noctilucent clouds photographed over Killygordon, Ireland on the morning of June 10. (© Brendan Alexander/Donegal Skies. All rights reserved.)

The season for noctilucent “night-shining” clouds is arriving in the northern hemisphere, when wispy, glowing tendrils of high-altitude ice crystals may be seen around the upper latitudes, shining long after the Sun has set. Found about 83 km (51 miles) up, noctilucent clouds (also called polar mesospheric clouds) are the highest cloud formations in the atmosphere. They’ve been associated with rocket launches and space shuttle re-entries and are now thought to also be associated with meteor activity… and for some reason, this year they showed up a week early.


Noctilucent clouds (NLCs) form between 76 to 85 kilometers (47 to 53 miles) above Earth’s surface when there is just enough water vapor to freeze into ice crystals. The icy clouds are illuminated by the Sun when it is just below the horizon, after darkness has fallen, giving them their night-shining properties. This year NASA’s AIM spacecraft, which is orbiting Earth on a mission to study high-altitude ice, started seeing noctilucent clouds on May 13th.

AIM map of noctilucent clouds over the north pole on June 8 (Credit: LASP/University of Colorado)
AIM map of noctilucent clouds over the north pole on June 8
(Credit: LASP/University of Colorado)

“The 2013 season is remarkable because it started in the northern hemisphere a week earlier than any other season that AIM has observed,” reports Cora Randall of the Laboratory for Atmospheric and Space Physics at the University of Colorado. “This is quite possibly earlier than ever before.”

The early start is extra-puzzling because of the solar cycle. Researchers have long known that NLCs tend to peak during solar minimum and bottom-out during solar maximum — a fairly strong anti-correlation. “If anything, we would have expected a later start this year because the solar cycle is near its maximum,” Randall says. “So much for expectations.”

Read more on the NASA AIM page here, and watch the Science@NASA video below for the full story. (Also, check out some very nice NLC photos taken last week in the UK by Stuart Atkinson at Cumbrian Sky.)

Source: NASA