Jun 15, 2017 Mercury is no longer geologically active. Mercury has no atmosphere and a weak magnetic field, so it receives the Sun’s radiation with little deflection, similar to Earth’s Moon. Since the Moon is also an airless world, with only traces of a magnetic field, perhaps the Moon…
Jun 14, 2017 Kristian Birkeland was called the first space scientist because of his pioneering experiments in the early 1900s. June 15th marks the 100th anniversary of his death. “It seems to be a natural consequence of our points of view to assume that the whole of space is filled…
Sep 28, 2016 Europa is not a harbor for life. In March of 1979 Voyager 1 found that Europa appeared to be completely encased in water ice, with few craters. Sinuous channels, called “rilles,” extend for thousands of kilometers across its face. Cycloid, dual ridge “faults” mystified NASA mission team…
Jun 12, 2017 Hot gravity? Astronomers have only one force in their bag of tricks: gravity. Anomalous observations, such as high temperature in galaxy clusters, “must be” caused by collisions. Shockwaves and ram pressure are invoked because it is assumed that celestial objects are pushing though a medium. It is…
Jun 9, 2017 A hidden star factory. NGC 6334 (the Cat’s Paw nebula) is also known as the Bear Claw nebula. It is 50 light-years across and approximately 5500 light-years away, using redshift distance calculations. It is part of a larger nebular complex near the heart of the Milky Way…
Jun 8, 2017 Mars is not a dried-out museum of life. “When dealing with other worlds, we must take care to remember that unfamiliar processes are possible and even likely in alien environments.” — Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center Mars is a freeze-dried wasteland…
Jun 7, 2017 Did many lakes make an ocean? It’s not going to do any good to land on Mars if we’re stupid. — Ray Bradbury Mars is not a rounded or softened world like Earth. It does not represent an environment that was weathered by rainfall or blowing dust….
Jun 6, 2017 Kinetic physics does not explain Saturn’s features. Planetary scientists already knew about material sticking out of the rings in a few places, but until Saturn reached its equinox it was not possible to measure how high these “ridges” are. Saturn’s main rings are approximately 140,000 kilometers…
Jun 2, 2017 Jupiter’s aurorae are generated by its own electromagnetic fields. There are many Pictures of the Day in the archives that discuss the planet, Jupiter—especially its electromagnetic interaction with its moons and the rest of the Solar System. Jupiter’s magnetosphere extends outward for nearly 650 million kilometers, reaching beyond Saturn’s orbit….
Jun 1, 2017 The Cassini mission is nearing its end. The Cassini spacecraft recently celebrated its twelfth year in orbit around Saturn, with its end of life approaching on September 15, 2017. Cassini was launched from Vandenberg Air Force Base on October 15, 1997. Including the Huygens lander, Cassini…
