OrbitalHub

NASA dixit:

“On Mars, wind rules. Wind has been shaping the Red Planet’s landscapes for billions of years and continues to do so today. Studies using both a NASA orbiter and a rover reveal its effects on scales grand to tiny on the strangely structured landscapes within Gale Crater.

NASA’s Curiosity Mars rover, on the lower slope of Mount Sharp — a layered mountain inside the crater — has begun a second campaign of investigating active sand dunes on the mountain’s northwestern flank. The rover also has been observing whirlwinds carrying dust and checking how far the wind moves grains of sand in a single day’s time.

Gale Crater observations by NASA’s Mars Reconnaissance Orbiter have confirmed long-term patterns and rates of wind erosion that help explain the oddity of having a layered mountain in the middle of an impact crater.

“The orbiter perspective gives us the bigger picture — on all sides of Mount Sharp and the regional context for Gale Crater. We combine that with the local detail and ground-truth we get from the rover,” said Mackenzie Day of the University of Texas, Austin, lead author of a research report in the journal Icarus about wind’s dominant role at Gale.

The combined observations show that wind patterns in the crater today differ from when winds from the north removed the material that once filled the space between Mount Sharp and the crater rim. Now, Mount Sharp itself has become a major factor in determining local wind directions. Wind shaped the mountain; now the mountain shapes the wind.

The Martian atmosphere is about a hundred times thinner than Earth’s, so winds on Mars exert much less force than winds on Earth. Time is the factor that makes Martian winds so dominant in shaping the landscape. Most forces that shape Earth’s landscapes — water that erodes and moves sediments, tectonic activity that builds mountains and recycles the planet’s crust, active volcanism — haven’t influenced Mars much for billions of years. Sand transported by wind, even if infrequent, can whittle away Martian landscapes over that much time.”

Video credit: NASA Jet Propulsion Laboratory

NASA dixit:

“Around 13 times per century, Mercury passes between Earth and the sun in a rare astronomical event known as a planetary transit. The 2016 Mercury transit occurred on May 9, between roughly 7:12 a.m. and 2:42 p.m. EDT.”

Wikipedia dixit:

“A transit of Mercury across the Sun takes place when the planet Mercury passes directly between the Sun and a superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Mercury can be seen as a very small black disk moving across the face of the Sun. Transits of Mercury with respect to Earth are much more frequent than transits of Venus, with about 13 or 14 per century, in part because Mercury is closer to the Sun and orbits it more rapidly. Transits of Mercury occur in May or November. The last four transits occurred in 1999, 2003, 2006, and May 9, 2016. The next will occur on November 11, 2019, and then on November 13, 2032. A typical transit lasts several hours.

On June 3, 2014, the Mars rover Curiosity observed the planet Mercury transiting the Sun, marking the first time a planetary transit has been observed from a celestial body besides Earth.”

Video credit: NASA’s Goddard Space Flight Center/Genna Duberstein

Music credit: Encompass by Mark Petrie