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Death Valley sliding stone mystery solved

The video above shows a famous sliding stone of Death Valley’s Racetrack Playa in motion. See it? It’s the big rock in the foreground. Watching this video, you become one of the first people on Earth to see a sliding stone in motion. Although their tracks across Racetrack Playa – a dry lake bed in Death Valley – have been observed and studied since the early 1900s, no one had ever seen the stones in motion … until now. What’s more, the researchers who captured this video say they now know what causes the stones to move.

This date in science: Pioneer 11 swept past Saturn

Image credit:  NASA/Ames

Image credit: NASA/Ames

September 1, 1979. On this date, NASA’s Pioneer 11 came within 13,000 miles (21,000 kilometers) of Saturn, making it the first spacecraft ever to sweep closely past that place. The spacecraft found a new ring for Saturn – now called the “F” ring – and also a new moon, Epimetheus. There were two Pioneer spacecraft. They were used to investigate Saturn’s rings and determine if a trajectory through the rings was safe for the upcoming Voyager visits. They paved the way for the even-more-sophisticated Voyager spacecraft, which were launched in 1977.

Everything you need to know: zodiacal light or false dawn

The zodiacal light – or false dawn – is an eerie light extending up from the eastern horizon, before sunrise, in autumn. You might also see it in the west after sunset, in springtime, in which case it’s called the false dusk. The light looks like a hazy pyramid of light extending up from the horizon. Follow the links inside to learn more about the zodiacal light.

No double moon on August 27

This image is circulating on Facebook, with the claim that Mars will appear as big and bright as a full moon on August 27, 2013.  It's a hoax.  Don't believe it.  Mars never appears as large as a full moon in Earth's sky.

This image sometimes circulates on Facebook, with the claim that Mars will appear as big and bright as a full moon on August 27, 2014. It’s a hoax. Don’t believe it. Mars never appears as large as a full moon in Earth’s sky.

The famous double moon on August 27 hoax has come through like gangbusters this August. No one expected that! This hoax is now 11 years old. Still, clearly, not everyone knows it’s a hoax. Google searches have made this post the most popular on our site for the past week. An email must be circulating – somewhere, social media must be buzzing – with the suggestion that – on August 27, 2014 – Mars will appear as large as a full moon in Earth’s sky. And that is just not true.

Testing a space rover under Alaskan ice

Scientists test a device on an Alaska glacier that could be used to explore an icy moon of Jupiter.

Pluto-bound New Horizons crosses Neptune’s orbit

Neptune and Triton, as captured by the New Horizons spacecraft on July 10, 2014, about one year before its planned 2015 Pluto encounter.  New Horizons crosses Neptune's orbit on August 25, 2014.

Neptune and Triton, as captured by the New Horizons spacecraft on July 10, 2014, about one year before its planned 2015 Pluto encounter. New Horizons crosses Neptune’s orbit on August 25, 2014. Image via NASA / JHU / APL New Horizons spacecraft.

On August 25, 2014, the Pluto-bound New Horizons spacecraft is crossing the orbit of the 8th planet in our solar system, Neptune. NASA says this is New Horizons’ last major crossing en route to becoming the first probe to make a close encounter with distant Pluto on July 14, 2015. While traveling toward Pluto earlier this summer, New Horizons spacecraft imaged the very distant Neptune and Triton using the LORRI (LOng Range Reconnaissance Imager) camera from a distance of 3.957 billion kilometers / 2.457 billion miles. Triton is visible at the 10 o’clock position in relation to Neptune.

Five finalists for Philae landing site on Rosetta’s comet

Landing site candidate A, larger lobe of Comet.  Image via OSIRIS NAC Rosetta.

Landing site final candidate A, larger lobe of Comet 67P/Churyumov–Gerasimenko. One km square area. Image via OSIRIS NAC Rosetta.

The Rosetta mission’s Philae lander is due to set down on Comet 67P/Churyumov–Gerasimenko on November 11, 2014. Rosetta has been moving in tandem with this comet since August 6, the first spacecraft ever to rendezvous with a comet and follow it in orbit. Today (August 25, 2014), ESA named five finalists as potential sites for Philae’s spectacular comet landing. Interesting to see that the prime sites are on differing terrain. They are far more diverse than I expected. One close-up image above; the other four inside.

Back to the future with Neptune’s fascinating moon Triton

Neptune and Triton, via Voyager 2.

Neptune and Triton, via Voyager 2.

On the anniversary of Voyager 2′s encounter with Neptune and Triton … an awesome collection of restored Voyager 2 images, plus the link between Triton and Pluto.

Are tornado outbreaks on the rise?

Two tornadoes over the Great Plains. Image Credit: NOAA Legacy Photo; OAR/ERL/Wave Propagation Laboratory.

Two tornadoes over the Great Plains. Image Credit: NOAA Legacy Photo; OAR/ERL/Wave Propagation Laboratory.

A new study has found that dangerous tornado outbreaks — days with multiple strong tornadoes—are on the rise in the U.S.

Longest lunar month of 2014 starts on August 25

Simulated view of the cycle of the moon's phases from new moon to new moon. This cycle is known as the lunar month. From the years 1760 to 2200, the longest lunar month was 29 days 19 hours and 58 minutes and the shortest 29 days 6 hours and 34 minutes.

Simulated view of the moon’s phases. The period of time from new moon to new moon is known as the lunar month, lunation or synodic month. From the years 1760 to 2200, the longest lunar month spans 29 days 19 hours and 58 minutes (Dec. 9, 1787 to Jan. 8, 1778) while the shortest lasts for 29 days 6 hours and 34 minutes (June 12 to July 12, 1885).

The longest lunar month of the year begins with the new moon of August 25, 2014, and ends with the new moon of September 24, 2014. This lunar month – the period of time between successive new moons – lasts for 29 days 16 hours and 1 minute. That’s 3 hours and 17 minutes longer than the mean lunar month of 29 days 12 hours and 44 minutes.