Why is the Sky Dark at Night?

The Minute Physics folks have created another great video, this time explaining why the sky is dark at night. Although at first glance it seems like an easy question to answer, throw in Olbers’ Paradox (the light from an infinite amount of stars should make the night sky completely bright) and it really is quite a complicated matter. In fact, it takes the Minute Physics teams nearly four minutes to explain it all!

How Many Asteroids Are Out There?

Answer: a LOT. And there’s new ones being discovered all the time, as this fascinating animation by Scott Manley shows.


Created using data from the IAU’s Minor Planet Center and Lowell Observatory, Scott’s animation shows the progression of new asteroid discoveries since 1980. The years are noted in the lower left corner.

As the inner planets circle the Sun, asteroids light up as they’re identified like clusters of fireflies on a late summer evening. The clusters are mainly positioned along the outer edge of Earth’s orbit, as this is the field of view of most of our telescopes.

Once NASA’s WISE spacecraft begins its search around 2010 the field of view expands dramatically, as well as does the rate of new discoveries. This is because WISE’s infrared capabilities allowed it to spot asteroids that are composed of very dark material and thus reflect little sunlight, yet still emit a telltale heat signature.

While Scott’s animation gives an impressive — and somewhat disquieting — illustration of how many asteroids there are knocking about the inner Solar System, he does remind us that the scale here has been very much compacted; a single pixel at the highest resolution corresponds to over 500,000 square kilometers! So yes, over half a million asteroids is a lot, but there’s also a lot of space out there (and this is just a 2D top-down view too… it doesn’t portray any vertical depth.)

While most asteroids are aligned with the horizontal plane of the Solar System, there are a good amount whose orbits take them at higher inclinations. And on a few occasions they even cross Earth’s orbit.

(Actually, on more than just a few.)

Read: 4700 Asteroids Want to Kill You

An edge-on view of the Solar System shows the positions of asteroids identified by the NEOWISE survey. About 4700 potentially-hazardous asteroids (PHAs) have been estimated larger than 100 meters in size. (NASA/JPL-Caltech)

As far as how many asteroids there are… well, if you only consider those larger than 100 meters orbiting within the inner Solar System, there’s over 150 million. Count smaller ones and you get even more.

I don’t know about you but even with the distances involved it’s starting to feel a little… crowded.

You can see more of Scott Manley’s videos on YouTube here (including some interesting concepts on FTL travel) and learn more about asteroids and various missions to study them here.

Inset image: the 56-km (35-mile) wide asteroid Ida and its satellite, seen by the Galileo spacecraft in 1993. (NASA)

Fly Over California Alongside a Space Shuttle!

A view of Endeavour and SCA over California from one of NASA’s F/A-18 chase planes (NASA/DFRC)

We’ve shared several videos from Endeavour’s trip to Los Angeles last week, taken by excited spectators along various portions of the flight path, but what was it like for the crews of the two NASA F/A-18 chase planes that accompanied the orbiter and SCA every step of the way?

Watch the video below, and put yourself in the pilot’s seat…

Shared by NASA’s Dryden Flight Research Center, the video shows footage taken from the viewpoint of one of the chase planes as Endeavour was ferried aboard a Shuttle Carrier Aircraft from Edwards Air Force Base to Los Angeles International Airport.

Along the way SCA pilots Jeff Moultrie and Bill Rieke, both from NASA’s Johnson Space Center, guided the 747 over such landmarks as the State Capitol in Sacramento, the Golden Gate Bridge at San Francisco, and NASA’s Ames Research Center.

Once over the Los Angeles area Endeavour passed over well-known landmarks like Griffith Observatory, the Hollywood sign, Dodger Stadium, NASA’s Jet Propulsion Laboratory, Malibu Beach and the Santa Monica Pier, and Disneyland.

After several low flybys of the runway — some under 300 feet! — the SCA touched down at LAX on Runway 25L at 12:51 p.m. PDT.

NASA’s four F/A-18 Hornet aircraft, operated by Dryden Flight Research Center, are commonly called chase planes and fill the role of escort aircraft during research missions. They also are used as camera platforms for research missions that must be photographed or videotaped. Two of these chase planes accompanied Endeavour on its flight for such documentation as well as for security.

See more images of the F/A-18s here, and for more photos of Endeavour’s trip to California check out the NASA photographer photo set on Flickr.

Video: Dryden TV

Award-Winning Short Film is Set on an Exoplanet

A new short film called “Grounded” portrays an astronaut stranded on another planet. The film combines great storytelling with stunning effects, and the visuals are nothing short of convincingly and stunningly real. But the ethereal, dream-like nature of the film is reminiscent of the ending of the movie “2001,” so, actually understanding the plot is not what the film is about. Instead it invites “unique interpretation and reflection by the viewer,” according to the description of the film. In under 8 minutes, the film explores themes of “aging, inheritance, paternal approval, cyclic trajectories, and behaviors passed on through generations,” which is ambitious for a sci-fi genre short. “Grounded” was written, directed, edited and produced by Kevin Margo. It is perhaps one of the best short films I’ve ever seen.
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Beautiful Timelapse: Purely Pacific Northwest

Here’s a wonderful new timelapse from photographer John Ecklund, a photographer from Portland, Oregon. He captures incredible views of the Milky Way over Crater Lake, Mount Hood, Mount St. Helens, the Painted Hills and more, even nabbing a few meteors and a pass of the International Space Station.

“I choose to shoot locations that appeal to the way I would like to interpret the story of time,” says Ecklund. “Here in the Pacific Northwest, there are endless opportunities to document the magnificence of the world around us. I have discovered that when time is the storyteller, a special kind of truth emerges.”
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Timelapse from Thierry Legault: One Night on the Pic-du-Midi Observatory

Here’s a really unique video from one of our favorite astrophotographers, Thierry Legault. Thierry sent us a full HD time-lapse of the full sky during one full night (August 7-8) over the Pic-du-Midi Observatory in the French Pyrenees. At 2,877 meters in altitude, this is the highest observatory in France. The video is taken with a fisheye lens, and so the view creates what appears to be a tiny little world (Planet Pic-du-Midi, perhaps?). Visible are Saturn and Mars, then the Moon, Jupiter and Venus. And a passage of the ISS and an Iridium flare complete the planet-like scene. “The rotation of the sky around Polaris is easily noticeable,” Thierry wrote to Universe Today, “as well as the movement of circumpolar constellations such as Big Dipper. The main dome is the 1-meter telescope, I was there with three friends to learn how to use this telescope for future planetary missions. This telescope was used in the 60’s to prepare the Apollo lunar missions because of the quality of its optics and the very good seeing of this site.”

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Timelapse: Star Trails in Portugal

Astrophotographer Miguel Claro has compiled dozens of hours of timelapse photography – all taken in Portugal – creating one of the most amazing and idyllic night sky views, including several magical star trail observations. Included in the foreground are some historical features, such as Diana’s Temple in Évora, the 25th of April Bridge in Lisbon and scenes from the Dark Sky Alqueva, one of the first dark sky reserves in the world to be certified as “Star Light Tourism Destination.”

“It is the perfect place to find the Milky Way as well providing an incredible and overwhelming vision,” Claro wrote to UT, “where the depth of the sky has no limit. The light pollution effect existing in large cities, earned their magic through the peculiar form as it was captured in each image revealed in this video.”

Sit back, put the video in HD and large screen, turn on your speakers and enjoy! This is perfect if you need a short “get away from it all” during your day!
Continue reading “Timelapse: Star Trails in Portugal”

What If All of Kepler’s Exoplanets Orbited the Same Star?


That’s exactly the scenario shown by a mesmerizing animation called “Worlds” by Alex Parker — a single system containing 2299 multiple-transit planetary candidates identified to date by NASA’s Kepler space telescope, which is currently scrutinizing a field of view within the constellation Cygnus to detect the oh-so-faint reductions in brightness caused by planets passing in front of their stars.

The search requires patience and precision; it’s not really this crowded out there.

Alex’s animation takes 2299 candidates that have been observed multiple times, each shown to scale in relation to their home star, and puts them in orbit around one star, at their relative distances.

The result, although extravagantly impossible, is no less fascinating to watch. (I suggest going full screen.)

“The Kepler observatory has detected a multitude of planet candidates orbiting distant stars,” Alex writes on his Vimeo page. “The current list contains 2321 planet candidates, though some of these have already been flagged as likely false-positives or contamination from binary stars. This animation does not contain circumbinary planets or planet candidates where only a single transit has been observed, which is why ‘only’ 2299 are shown.

“A fraction of these candidates will likely be ruled out as false positives as time goes on, while the remainder stand to be confirmed as real planets by follow-up analysis,” Alex adds.

The white ellipses seen when the animation pulls back are the relative sizes of the orbits of Mercury, Venus and Earth.

At this time the Kepler mission has identified 2321 planetary candidates, with 74 exoplanets confirmed. See more on the Kepler mission here.

Animation: Alex Parker. Image: Kepler mission planet candidates family portrait (NASA Ames/Jason Rowe/Wendy Stenzel)

NASA’s Mighty Eagle Takes Flight; Finds Its Target

No, it’s not a UFO — it’s NASA’s “Mighty Eagle”, a robotic prototype lander that successfully and autonomously found its target during a 32-second free flight test at Marshall Space Flight Center yesterday, August 16.

You have to admit though, Mighty Eagle does bear a resemblance to classic B-movie sci-fi spacecraft (if, at only 4 feet tall, markedly less threatening to the general populace.)

Fueled by 90% pure hydrogen peroxide, Mighty Eagle is a low-cost “green” spacecraft designed to operate autonomously during future space exploration missions. It uses its onboard camera and computer to determine the safest route to a pre-determined landing spot.

During the August 16 test flight, Mighty Eagle ascended to 30 feet, identified a target painted on the ground 21 feet away, flew to that position and landed safely — all without being controlled directly.

“This is huge. We met our primary objective of this test series — getting the vehicle to seek and find its target autonomously with high precision,” said Mike Hannan, controls engineer at Marshall Space Flight Center. “We’re not directing the vehicle from the control room. Our software is driving the vehicle to think for itself now. From here, we’ll test the robustness of the software to fly higher and descend faster, expecting the lander to continue to seek and find the target.”

In the wake of a dramatically unsuccessful free flight test of the Morpheus craft on August 9, another green lander designed by Johnson Space Center, the recent achievements by the Mighty Eagle team are encouraging.

Here’s a video from a previous test flight on August 8:

Future tests planned through September will have the lander ascend up to 100 feet before landing. Read more here.

The Mighty Eagle prototype lander was developed by the Marshall Center and Johns Hopkins University Applied Physics Laboratory in Laurel, Md., for NASA’s Planetary Sciences Division, Headquarters Science Mission Directorate Image/video: NASA/Marshall Space Flight Center

Curiosity’s Landing Through the Eyes of One of Her 3,000 Builders

We all have seminal moments that mark our lives; some just are way more cool than others. Mark Rober designs spacecraft at the Jet Propulsion Laboratory and is just one of over 3,000 people who helped design, build, tweak, launch, navigate and land the Curiosity Rover on Mars. “I spent 7 years working NASA’s Curiosity Rover,” Rober said via Twitter. “I made this video to try to capture what it felt like to see her land.”

Seven years of his life came down to seven minutes of terror… or in Mark’s case, seven minutes of shivering.

Congrats, Mark, and to all your thousands of compatriots. Thanks for sharing the journey with the rest of us.