Universe's missing mass found hiding between galaxies
Thin threads of gas may hold 30% of matter we haven't been able to spot.
Cosmological Researcher and Community Outreach Coordinator, Department of Astronomy, Ohio State University
Johan Hidding / Flickr
We know how much total matter is in the universe, including "normal" matter (things like stars, planets, you, me) and more mysterious "dark" matter. However, only about 10% of the normal matter has been accounted for in surveys of galaxies. Astronomers have long suspected the missing matter sits in threads of gas between galaxies, but it's hard to detect because it's very tenuous.
What's new: Researchers now report spotting about 30% of the missing matter by looking for its shadow in the cosmic microwave background — the afterglow of the big bang itself. The background light filters through the gas and gets bumped up to higher energies through collisions with the hot particles, leading to a subtly higher observed temperature between galaxies.
Why it matters: While it doesn't completely solve the mystery of the missing matter, the research may help us paint a fuller family portrait of the universe. By understanding what it's made of, we can learn more about its past and future evolution.
WASP-12b compared to Jupiter. Image credit: Aldaron / Wikipedia
The extra-solar planet ("exoplanet") known as WASP-12b is perhaps the strangest world found yet. While known for almost a decade, astronomers recently observed it during an eclipse, allowing them to measure its reflectivity (or albedo) for the first time.
What they saw: Surprisingly, WASP-12b has only half the albedo of the Moon, and about 1/6th that of the Earth, meaning it reflects very little light.
It doesn't end there — the exoplanet is twice as large as Jupiter and orbits 16 times closer than Mercury does around the sun.This proximity heats WASP-12b to almost 5,000 degrees Fahrenheit, meaning that despite its blackness it glows deep red like a massive gaseous charcoal briquette.
The bottom line: The variety of worlds we're finding in the galaxy far surpasses even the wildest sci-fi stories, and is providing insight into the range of physics and chemistry in the universe.
NASA/JPL-Caltech/S. Stolovy (SSC/Caltech)
By studying the motions of a particularly dense cloud of gas, astronomers have inferred the existence of a new black hole near the center of the Milky Way galaxy. It's not confirmed yet, but it's estimated to weigh in at a whopping 100,000 times the mass of our sun.
That's big, but not the biggest — that title goes to Sagittarius A*, a supermassive black hole sitting in the middle of our galaxy that has a mass 4 million times greater than our sun.
Why it matters: This "intermediate" class of black hole provides clues to the formation of their bigger cousins. It seems that every galaxy hosts a giant black hole. How do these black holes form and grow? What's the connection between giant black holes and the evolution of their host galaxies? Having a "missing link" in our own backyard helps answer those questions.
Rebecca Zisser / Axios
There are rumors within the astronomical community that LIGO, the super-advanced gravitational wave observatory, may have spotted the signature of two neutron stars colliding.
What they are: Neutron stars are the collapsed cores of massive stars, and are some of the most exotic objects in the universe. They can form in pairs that eventually collide and release massive amounts of energy. Those collisions also create subtle ripples in gravity that might have been detected by LIGO.
What's new: This specific event was seen with traditional telescopes, but it's the first time the same collision may have been detected from radiation and gravitational waves. The LIGO team is checking the validity of their results.
Why it matters: Much of our universe is hidden from us, and gravitational waves give us access to mysterious events. Vibrations from neutron star mergers, for example, can help us understand the origin of the universe's heaviest elements. Spacetime itself is ringing like a bell — we just need to listen.
Our expert voices conversation on "How to look for alien life."
We find ourselves in a universe that appears, at first glance, ripe for life. Liquid water, abundant even in our own solar system (though most of it is hiding underneath thick icy crusts), amino acids hitching rides on comets, simple proteins found in young systems, millions upon millions of stars exactly like our sun in just the Milky Way galaxy.
By all appearances we should not be alone, and yet we don't see a single sign of anybody else, anywhere.
The chances of life appearing in the universe are obviously greater than 0 (otherwise I wouldn't be writing this and you wouldn't be reading this), but seem far, far less than 1.
What Earth got right: We can understand why planets like Mars and Venus wound up dead — too small to sustain a protective magnetic field and choking on its own oppressive atmosphere, respectively — even though they had a decent shot. But we don't fully understand the special sauce that makes life possible. So we're playing a numbers game. How many planets are out there? How many have liquid water? How many have a stable star and the right cocktail for life? It's only by obsessive, detailed observations will we crack it.
The other voices in the conversation: