News by Subject Space & Planetary

How fast the universe is expanding has been puzzling astronomers for almost a century. Different studies keep coming up with different answers -- which has some researchers wondering if they've overlooked a key mechanism in the machinery that drives the cosmos. Now, by pioneering a new way to measure how quickly the cosmos is expanding, a team led by UCLA astronomers has taken a step toward resolving the debate.

In its last days, the Cassini spacecraft looped between Saturn and its rings so that Earth-based radio telescopes could track the gravitational tug of each. Scientists in Italy and the U.S. have now used these measurements to determine the mass of the rings and estimate its age, which is young: 10-100 million years. This supports the hypothesis that the rings are rubble from a comet or Kuiper Belt object captured late in Saturn's history.

Using images and thermal data collected by NASA's Lunar Reconnaissance Orbiter (LRO), Southwest Research Institute scientists and their collaborators have calculated the ages of large lunar craters across the moon to be less than 1 billion years. By comparing the impact history of the moon with Earth's craters over this interval, they discovered that the rate of sizable asteroid collisions has increased by a factor of two to three on both bodies over the last 290 million years.

A new technique for understanding the star-forming history of the Milky Way in unprecedented detail makes it possible to determine the ages of stars at least two times more precisely than conventional methods, Embry-Riddle Aeronautical University researchers reported Jan. 10, 2019, at the American Astronomical Society (AAS) meeting.