Missing matter
By Yuanming Wang, University of Sydney and Tara Murphy, University of Sydney
We’ve all looked up at night and admired the brightly shining stars. Beyond making a gorgeous spectacle, measuring that light helps us learn about matter in our galaxy, the Milky Way.
When astronomers add up all the ordinary matter detectable around us (such as in galaxies, stars and planets), they find only half the amount expected to exist, based on predictions. This normal matter is “baryonic”, which means it’s made up of baryon particles such as protons and neutrons.
But about half of this matter in our galaxy is too dark to be detected by even the most powerful telescopes. It takes the form of cold, dark clumps of gas. In this dark gas is the Milky Way’s “missing” baryonic matter.
Thanks to the discovery of five twinkling galaxies in a rare alignment, astronomers have been able to calculate for the first time the properties and geometry of an invisible gas cloud in space.
December 23, 2020 at 8:00 am
Discoveries about the cosmos and ancient life on Earth tantalized scientists and the public in 2020. But these big claims require more evidence before they can earn a spot in science textbooks.
Cloudy with a chance of life
The scorching hellscape next door may be a place to look for life. Telescopes trained on Venus’ clouds spotted traces of phosphine in quantities that suggest something must be actively producing the gas (
SN: 9/14/20). On Earth, phosphine is emitted by certain bacteria or industrial processes, leading some astrobiologists to speculate that microbes may be living in Venus’ relatively temperate upper atmosphere. But other research teams’ analyses suggest the phosphine detection was a misread perhaps the result of a fluke in data processing (
December 23, 2020
Astronomers used radio waves to study conditions in the vicinity of Proxima Centauri, the nearest star to our sun. The results suggest Proxima’s 2 known planets are likely bathed in intense radiation from this star, casting doubt on the planets’ potential for life.
Artist’s concept of huge flares on Proxima Centauri, which unleash ionizing radiation. This radiation could be dangerous for any possible life on planets orbiting close to the star. Image via NASA/ ESA/ G. Bacon (STScI)/
This month, even as some astronomers are talking about a possible mystery radio signal from Proxima Centauri – a signal of interest to astronomers who search for intelligent life beyond Earth – other astronomers are talking about space weather in the vicinity of this star, which is the nearest star to our sun. Space weather in Proxima’s vicinity, they are saying, might make life on its planets difficult or even impossible.