Universe Today

January 14, 2025January 14, 2025 by Brian Koberlein

Here's How We Could Measure the Mass of SgrA* to Within One Solar Mass

Image of the supermassive black hole Sag A* seen in polarized light. Credit: EHT Collaboration

There is a gravitational monster at the heart of our galaxy. Known as Sagittarius A*, it is a supermassive black hole with a mass of more than four million Suns. Long-term observations of the stars closely orbiting Sag A* place it at about 4.3 solar masses, give or take 100,000 or so. Observations of light near its horizon by the Event Horizon Telescope pin the mass down to 4.297 solar masses, give or take about 10,000. Those results are astoundingly precise given how difficult the mass is to measure, but suppose we could determine the mass of our galaxy’s black hole to within a single solar mass. That might be possible with gravitational wave astronomy.

January 13, 2025January 11, 2025 by Paul M. Sutter

How to Debate a Flat-Earther

The problem with debating a flat-Earther is that they didn’t arrive at their conclusions from the weight evidence, so using the evidence isn’t going to work to change their minds.

January 13, 2025January 13, 2025 by Mark Thompson

LIGO Has Detected Unusual Black Holes Merging, But they Probably Don’t Explain Dark Matter

The traditional theory of black hole formation seems to struggle to explain how black holes can merge into larger more massive black holes yet they have been seen with LIGO. It’s possible that they may have formed at the beginning of time and if so, then they may be a worthy candidate to explain dark matter but only if there are enough of them. A team of researchers recently searched for microlensing events from black holes in the Large Magellanic Cloud but didn’t find enough to account for more than a fraction of dark matter.

January 13, 2025January 13, 2025 by Evan Gough

Gravitational Waves Could Give Us Insights into Fast Radio Bursts

This artist's illustration shows a neutron star with a powerful magnetic field, a magnetar. Scientists want to know if magnetars can generate both Fast Radio Bursts and Gravitational Waves. Image Credit: ESO/L. Calçada

Fast Radio Bursts (FRBs) are mysterious pulses of energy that can last from a fraction of a millisecond to about three seconds. Most of them come from outside the galaxy, although one has been detected coming from a source inside the Milky Way. Some of them also repeat, which only adds to their mystery.

Though astrophysicists think that a high-energy astrophysical process is the likely source of FRBs, they aren’t certain how they’re generated. Researchers used gravitational waves (GWs) to observe one nearby, known source of FRBs to try to understand them better.

January 13, 2025January 13, 2025 by Evan Gough

As We Explore the Solar System, Radiation Will Be One of Our Greatest Threats

Astronauts are vulnerable to radiation from the Sun and other sources. They're even more vulnerable beyond the ISS, on missions to the lunar or Martian surfaces. However, different countries and space agencies assess the risk differently. That needs to change. Image Credit: NASA

The Sun can kill. Until Earth developed its ozone layer hundreds of millions of years ago, life couldn’t venture out onto dry land for fear of exposure to the Sun’s deadly ultraviolet radiation. Even now, the 1% of its UV radiation that reaches the surface can cause cancer and even death.

Astronauts outside of Earth’s protective ozone layer and magnetic shield are exposed to far more radiation than on the planet’s surface. Exposure to radiation from the Sun and elsewhere in the cosmos is one of the main hurdles that must be cleared in long-duration space travel or missions to the lunar and Martian surfaces.

Unfortunately, there’s no harmonized approach to understanding the complexity of the hazard and protecting astronauts from it.

January 13, 2025January 13, 2025 by Matt Williams

LIGO Fails to Find Continuous Gravitational Waves From Pulsars

Illustration of a pulsar with powerful magnetic fields. Credit: NASA's Goddard Flight Center/Walt Feimer

In February 2016, scientists working for the Laser Interferometer Gravitational-Wave Observatory (LIGO) made history by announcing the first-ever detection of gravitational waves (GW). These waves, predicted by Einstein’s Theory of General Relativity, are created when massive objects collide (neutron stars or black holes), causing ripples in spacetime that can be detected millions or billions of light years away. Since their discovery, astrophysicists have been finding applications for GW astronomy, which include probing the interiors of neutron stars.

For instance, scientists believe that probing the continuous gravitational wave (CW) emissions from neutron stars will reveal data on their internal structure and equation of state and can provide tests of General Relativity. In a recent study, members of the LIGO-Virgo-KAGRA (LVK) Collaboration conducted a search for CWs from 45 known pulsars. While their results showed no signs of CWs emanating from their sample of pulsars, their work does establish upper and lower limits on the signal amplitude, potentially aiding future searches.

January 13, 2025January 13, 2025 by Andy Tomaswick

Astronauts Deploy the First Wooden Satellite into Orbit

Wood has been a mainstay of human machines and construction for millennia. Its physical properties offer capabilities that are unmatched by almost any synthetic replacements. However, it has only very rarely been used in space. That might change based on the results of a new test run by Japan’s Space Agency (JAXA). LignoSat, one of the world’s first wooden satellites, was deployed from the ISS in December.

January 13, 2025January 13, 2025 by Mark Thompson

Dormancy Could Be One of the Keys to Life on Earth (and Beyond)

It’s easy to forget that, despite life having existed on Earth for billions of years and despite our relatively carefree existence from total destruction, throughout history there have been events that wiped out nearly everything! Fortunately for many life forms, they have the ability to go dormant and enter a state of reversible, reduced metabolic activity. In this state they are protected from decay and can survive long harsh periods where life would otherwise not survive. Is it just possible therefore that dormancy could also allow life to survive on other worlds like Mars or Venus?

January 12, 2025January 11, 2025 by Paul M. Sutter

The Wavey Reality Behind the Uncertainty Principle

An artist view of primordial gravitational waves. Credit: Carl Knox, OzGrav/Swinburne University of Technology

It’s turns out that you don’t need a high-powered quantum experiment to observe Heisenberg’s uncertainty Principle. You just need to go the beach.

January 12, 2025January 12, 2025 by Mark Thompson

BepiColombo Just Completed its Sixth Flyby of Mercury. Here are the Best Images

It’s not unusual for space probes to complete gravitational flyby manoeuvres en route to their destination. It’s a bit more unusual when the flyby is at the destination planet. ESA’s BepiColombo spacecraft is manoeuvring around Mercury into its final orbit. With each flyby it gets closer and closer and closer until its finally captured by Mercury’s gravity in 2026. During the latest flyby, stunning images of the nearest planet to the Sun were captured from just a few hundred km. Checkout the best and most stunning images of Mercury yet.