Showing posts from November, 2019

Meet Hygiea, the Smallest Dwarf Planet in Our Solar System Source:   By Javier Barbuzano, Eos/AGU. Excerpt: Around 2 billion years ago, two large rock bodies hit each other in the main asteroid belt, a region between the orbits of Mars and Jupiter populated by fragments of rocks of various sizes. The impactor, with a size ranging from 75 to 150 kilometers in diameter, hit a body at least 4 times larger. Astronomers have known about this impact for a long time because it created a whole family of asteroids in the main asteroid belt, formed by the celestial body Hygiea and almost 7,000 smaller asteroids that have similar orbits. Hygiea itself has been considered an asteroid since it was discovered in 1849 by Italian astronomer Annibale de Gasparis. With a diameter just over 430 kilometers, it is the fourth-largest object in the main asteroid belt. New observations obtained with the Very Large Telescope (VLT), located in Chile and operated by the European Sout

Curiosity Rover Reveals Oxygen Mystery in Martian Atmosphere Source:   By Sarah Stanley, Eos/AGU. Excerpt: The Martian atmosphere is thin and cold and consists mostly of carbon dioxide. Although certainly unsuitable for humans, Martian air could hold clues to whether other life-forms live—or once lived—on the Red Planet. Now Trainer et al. report the first measurements of the five major components of the Martian atmosphere captured over several seasonal cycles. ...On average, the data revealed, the equatorial Martian atmosphere consists of 95% carbon dioxide, 2.59% nitrogen, 1.94% argon, 0.161% oxygen, and 0.058% carbon monoxide. However, throughout the year, some of these concentrations vary widely because of seasonal freezing of carbon dioxide at the planet’s poles, which periodically removes much of this gas from the atmosphere. Seasonal polar freezing—and subsequent thawing—of carbon dioxide also causes atmospheric pressure to rise and fall t

How Enceladus got its water-spewing tiger stripes Source:   By Adam Mann, Science Magazine. Excerpt: Researchers say they have solved a long-standing mystery about Saturn’s tiny, frozen moon Enceladus: why its south pole features long, water-spewing geysers known as tiger stripes. The study could also help explain why these unique formations aren’t seen on any other satellite in the solar system. Enceladus became a star attraction in 2005, when NASA’s Cassini mission photographed enormous jets of water ice and vapor emanating from four parallel slashes near its south pole. Since then, researchers have detected organic molecules and hydrogen in the jets—potential food for microbes—making Enceladus one of the top destinations in the search for life elsewhere in the Solar System. ...As it orbits around Saturn, Enceladus experiences gravitational tidal forces that squeeze and heat it. ...According to the new study, led by Douglas Hemingway of the

Voyager 2’s Discoveries From Interstellar Space Source:   By Kenneth Chang. The New York Times. Excerpt: The Voyager 2 spacecraft burst out of the bubble of gases expanding from the sun and into the wild of the Milky Way a year ago. It was the second spacecraft to cross that boundary and directly observe the interstellar medium. Its faster-moving twin, Voyager 1, made the crossing six years earlier, in August 2012. Launched 42 years ago, when Jimmy Carter was president, the twin spacecraft have persisted far longer than envisioned, as has their ability to send scientific findings home to Earth. In a series of papers published on Monday in Nature Astronomy [], scientists report what Voyager 2 observed at the boundary of the solar wind’s bubble and beyond....