Showing posts from July, 2018

Ancient craters on Mars reveal how the planet’s tilt has changed over time Source:   By Katherine Kornei, Science Magazine. Excerpt: Earth is a tilted planet—it lists by 23.5°. This “obliquity” causes the North Pole to sometimes tilt toward the sun and sometimes away, giving us the seasons. Now, researchers have revealed how Mars’s obliquity has changed over the last 3.5 billion years, results that could reveal how frequently water ice and snow would have melted to liquid on the Red Planet. To conduct the study, scientists assembled computer models of Mars with different obliquities and bombarded each version of the planet with asteroids. Elliptical craters—created by asteroids hitting the planet at shallow angles—tended to be more evenly distributed over the models with larger obliquities. On more upright planets, the elliptical craters tended to cluster around the equator. By comparing their models with the distribution of more than 1500 elliptical

What does Mars’ lake mean for the search for life on the Red Planet? Source:   By Lisa Grossman, Science Magazine. Excerpt: The search for life on Mars just got a lot more interesting. For decades, scientists have looked at ...finding regions where life could have taken root billions of years ago, when the Martian climate was warmer and wetter. But on July 25, researchers announced they had spotted signs of a large lake of liquid water hiding beneath thick layers of ice near the Red Planet’s south pole ( SN Online: 7/26/18 ). If the lake’s existence is confirmed, we could find microbes living on Mars today. That report changes the calculus for astrobiologists who want to protect any existing extraterrestrial life from being wiped out or obscured by introduced species from Earth.... Mars landers and rovers are cleaned to strict standards to avoid any possible contamination, even “without having anything you’d even call a pond,” says astrobiologist Lisa Pratt, NASA’s p

Outer space may have just gotten a bit closer Source:   By Paul Voosen, Science Magazine. Excerpt: ...A new study argues that the boundary between Earth’s atmosphere and outer space—known as the Kármán line—is 20 kilometers, or about 20%, closer than scientists thought. Though the new definition won’t make a difference for launching rockets and spacecraft, it could help clarify a legal debate that will set the rules for space policy—and commercial spaceflight—for years to come. Until now, most scientists have said that outer space is 100 kilometers away. At that point, it’s been thought, the speed needed to achieve lift in the superthin atmosphere is equal to the speed needed to simply orbit the planet; once there, a spacecraft’s horizontal pace would counteract the tug of Earth’s gravity. ...A close look shows that the traditional definition flies in the face of evidence, says Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Cent

Jupiter’s moon count reaches 79, including tiny ‘oddball’ Source:   By Emiliano Rodriguez Mega, Associated Press. Excerpt: Astronomers are still finding moons at Jupiter, 400 years after Galileo used his spyglass to spot the first ones. The latest discovery of a dozen small moons brings the total to 79, the most of any planet in our solar system. Scientists were looking for objects on the fringes of the solar system last year when they pointed their telescopes close to Jupiter’s backyard, according to Scott Sheppard of the Carnegie Institute for Science in Washington. They saw a new group of objects moving around the giant gas planet but didn’t know whether they were moons or asteroids passing near Jupiter. ...The team is calling one of the new moons an ‘oddball’ because of its unusual orbit. Sheppard’s girlfriend came up with a name for it: Valetudo, the great-granddaughter of the Roman god Jupiter. Valetudo is in Jupiter’s distant, outer swarm of moons that circles in the opposite dire

In a first, astronomers witness the birth of a planet from gas and dust Source:   By Daniel Clery, Science Magazine. Excerpt: In the first convincing observation of its kind, astronomers have directly imaged a newborn planet still forming around its star. The planet, hotter than any in our solar system, supports what astronomers have long believed: that such bodies are born of the disks of gas and dust that coalesce around young stars. “After decades of speculation, it’s nice to actually see one. It’s very comforting,” says astronomer Kevin Heng of the University of Bern in Switzerland, who was not involved in the work. The initial discovery was led by astronomer Miriam Keppler of the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany. Since 2015, her team has been regularly surveying hundreds of young stars for signs of exoplanets with a next-generation imaging instrument called SPHERE (for Spectro-Polarimetric High-contrast Exoplanet Research), at