What is it about galaxies and dark matter? Most, if not all galaxies are surrounded by halos of this mysterious, unknown, but ubiquitous material. And, it also played a role in galaxy formation. The nature of that role is something astronomers are still figuring out. Today, they’re searching the infant Universe, looking for the tiniest, brightest galaxies. That’s because they could help tell the tale of dark matter’s role in galactic creation.
According to our predominant cosmological models, Dark Matter makes up the majority of mass in the Universe (roughly 85%). While it is not detectable in visible light, its influence can be seen based on how it causes matter to form large-scale structures in our Universe. Based on ongoing observations, astronomers have determined that Dark Matter structures are filamentary, consisting of long, thin strands. For the first time, using the Subaru Telescope, a team of astronomers directly detected Dark Matter filaments in a massive galaxy cluster, providing new evidence to test theories about the evolution of the Universe.
NASA’s Plankton, Aerosol, Climate, ocean Ecosystem (PACE) satellite successfully launched and reached on Thursday, February 10th. The mission took off from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida, at 1:33 am EST 10:33 pm (PST) atop a SpaceX Falcon 9 rocket. About five minutes after launch, NASA confirmed that ground stations on Earth had acquired a signal from the satellite and were receiving data on its operational status and capabilities post-launch. For the next three years, the mission will monitor Earth’s ocean and atmosphere and study the effects of climate change.
Although supermassive black holes are common throughout the Universe, we don’t have many direct images of them. The problem is that while they can have a mass of millions or billions of stars, even the nearest supermassive black holes have tiny apparent sizes. The only direct images we have are those of M87* and Sag A*, and it took a virtual telescope the size of Earth to capture them. But we are still in the early days of the Event Horizon Telescope (EHT), and improvements are being made to the virtual telescope all the time. Which means we are starting to look at more supermassive black holes.
On January 21st, 2024, a meter-sized asteroid (2024 BX1) entered Earth’s atmosphere and exploded over Berlin at 12:33 am UTC (07:45 pm EST; 04:33 pm PST). Before it reached Earth, 2024 BX1 was a Near-Earth Asteroid (NEA) with an orbit that suggests it was part of the Apollo group. The fragments have since been located by a team of scientists from the Freie Universität Berlin, the Museum für Naturkunde (MfN), the German Aerospace Center (DLR), the Technische Universität Berlin, and the SETI Institute and identified as a rare type of asteroid known as “aubrites.”
The number of near misses, false starts, and legitimate disasters that have befallen our species since the day we took our first upright steps all those generations ago is too large to count and could honestly take up this entire book. I’ll give us humans this much, though: we’re survivors, through and through.
A recent study published in The Astrophysucal Journal Letters discusses the detection of water within the atmosphere of GJ 9827 d, which is a Neptune-like exoplanet located approximately 97 light-years from Earth, using NASA’s Hubble Space Telescope (HST), and is the smallest exoplanet to date where water has been detected in its atmosphere. This study was conducted by an international team of researchers and holds the potential to identify exoplanets throughout the Milky Way Galaxy which possess water within their atmospheres, along with highlighting the most accurate methods to identify the water, as well.
Proxima Centauri B is the closest exoplanet to Earth. It is an Earth-mass world right in the habitable zone of a red dwarf star just 4 light-years from Earth. It receives about 65% of the energy Earth gets from the Sun, and depending on its evolutionary history could have oceans of water and an atmosphere rich with oxygen. Our closest neighbor could harbor life, or it could be a dry rock, but is an excellent target in the search for alien life. There’s just one catch. Our usual methods for detecting biosignatures won’t work with Proxima Centauri B.
All stars form in giant molecular clouds of hydrogen. But some stars are extraordinarily massive; the most massive one we know of is about 200 times more massive than the Sun. How do these stars gain so much mass?
Though an estimated 100 million black holes roam among the stars in our Milky Way galaxy, astronomers have never identified an isolated black hole – until now. Following six years of meticulous observations, NASA’s Hubble Space Telescope has provided, for the first time ever, strong evidence for a lone black hole plying interstellar space.The black hole that was detected lies about 5,000 light-years away, in the Carina-Sagittarius spiral arm of our galaxy. However, its discovery allows astronomers to estimate, statistically, that the nearest isolated black hole to Earth might be as close as 80 light-years.Black holes are born from rare, monstrous stars (less than one-thousandth of the galaxy’s stellar population) that are at least 20 times more massive than our Sun. These stars explode as supernovae, and the remnant core is crushed by gravity into a black hole. Because the self-detonation is not perfectly symmetrical, the black hole may get a kick, and go careening through our galaxy like a blasted cannonball.Hubble can’t photograph the wayward black hole because it doesn’t emit any light, but instead swallows all radiation due to its intense gravitational pull. Instead, Hubble measurements capture the ghostly gravitational footprint of how the stealthy black hole warps space, which then deflects starlight from anything that momentarily lines up exactly behind it.Ground-based telescopes, which monitor the brightness of millions of stars in the rich star fields in the direction of the central bulge of our Milky Way, look for the tell-tale sudden brightening of one of them when a massive object passes between us and the star. Then Hubble follows up on the most interesting such events.Kailash Sahu of the Space Telescope Science Institute in Baltimore, Maryland, along with his team, made the discovery in a survey designed to find just such isolated black holes. The warping of space due to the gravity of a foreground object passing in front of a star located far behind it will momentarily bend and amplify the light of the background star as it passes in front of it. The phenomenon, called gravitational microlensing, is used to study stars and exoplanets in the approximately 20,000 events seen so far inside our galaxy.The signature of a foreground black hole stands out as unique among other microlensing events. The very intense gravity of the black hole will stretch out the duration of the lensing event for over 200 days. Also, If the intervening object was instead a foreground star, it would cause a transient color change in the starlight as measured because the light from the foreground and background stars would momentarily be blended together. But no color change was seen in the black hole event.Next, Hubble was used to measure the amount of deflection of the background star’s image by the black hole. Hubble is capable of the extraordinary precision needed for such measurements. The star’s image was offset from where it normally would be by two milliarcseconds. That’s equivalent to measuring the diameter of a 25-cent coin in Los Angeles as seen from New York City.This astrometric microlensing technique provided information on the mass, distance, and velocity of the black hole. The amount of deflection by the black hole’s intense warping of space allowed Sahu’s team to estimate it weighs seven solar masses.The isolated black hole is traveling across the galaxy at 90,000 miles per hour (fast enough to travel from Earth to the moon in less than three hours). That’s faster than most of the other neighboring stars in that region of our galaxy.“Astrometric microlensing in conceptually simple but observationally very tough,” said Sahu. “It is the only technique for identifying isolated black holes.” When the black hole passed in front of a background star located 28,000 light-years away in the galactic bulge, the starlight coming toward Earth was amplified for a duration of 265 days as the black hole passed by. However, it took several years of Hubble observations to follow how the background star’s position appeared to be deflected by the bending of light by the foreground black hole.The existence of stellar-mass black holes has been known since the early 1970’s, but all of them—until now—are found in binary star systems. Gas from the companion star falls into the black hole, and is heated to such high temperatures that it emits X rays. About two dozen black holes have had their masses measured in X-ray binaries through their gravitational effect on their companions.Black hole masses in X-ray binaries inside our galaxy range from 5 to 20 solar masses. Black holes detected in other galaxies by gravitational waves from mergers between black holes and companion objects have been as high as 90 solar masses.“Detections of isolated black holes will provide new insights into the population of these objects in our Milky Way,” said Sahu. He expects that his program will uncover more free-roaming black holes inside our galaxy. But it is a needle-in-a-haystack search. The prediction is that only one in 1500 microlensing events are caused by isolated black holes.NASA’s upcoming Nancy Grace Roman Space Telescope will discover several thousand microlensing events out of which many are expected to be black holes, and the deflections will be measured with very high accuracy.In a 1916 paper on general relativity, Albert Einstein predicted that his theory could be tested by observing the sun’s gravity offsetting the apparent position of a background star. This was tested by astronomer Arthur Eddington during a solar eclipse on May 29, 1919. Eddington measured a background star being offset by 2 arc seconds, validating Einstein’s theories. Both scientists could hardly have imagined that over a century later this same technique would be used – with unimaginable precision of a thousandfold better — to look for black holes across the galaxy.
Fifty-five million light years from Earth there is a massive elliptical galaxy known as Messier 87, or M87 for short. It was cataloged by Charles Messier in the 1700s, along with 102 other fuzzy objects in the sky that were definitely not comets. It was confirmed to be a galaxy in the early 1900s, and by the mid-twentieth century, it was known to be a powerful radio source. But these days it is most widely known for the supermassive black hole deep in its core. Called M87*, it is the first black hole directly observed by astronomers. The first image of M87* was released in 2019, and was based on observations taken by the Event Horizon Telescope (EHT) in 2017. Now a new image based on 2018 data has been released. The similarities and differences between the two images tell us a great deal about M87* and black holes in general.
This strange-looking galaxy seems to be a spiral with a long tidal tail stretching away. It’s known as Arp 122, and it’s actually not just one galaxy, but two separate galaxies. NGC 6040 is the warped spiral galaxy seen edge-on, while LEDA 59642 is the round, face-on spiral. The two are colliding about 540 million light-years from Earth, and it gives us a preview of the Milky Way’s future collision with Andromeda.
Maybe Mars isn’t as dry as we thought. ESA’s Mars Express has revealed new details about a region near Mars’ equator that could contain a massive deposit of water ice several kilometers deep. If it is indeed ice, there is enough of it in this one deposit that if melted, water would cover the entire planet up to 2.7 meters (almost 9 feet) deep.
Mars is the next frontier of human space exploration, with NASA, China, and SpaceX all planning to send crewed missions there in the coming decades. In each case, the plans consist of establishing habitats on the surface that will enable return missions, cutting-edge research, and maybe even permanent settlements someday. While the idea of putting boots on Martian soil is exciting, a slew of challenges need to be addressed well in advance. Not the least of which is the need to locate sources of water, which consist largely of subsurface deposits of water ice.
The very early Universe was a dark place. It was packed with light-blocking hydrogen and not much else. Only when the first stars switched on and began illuminating their surroundings with UV radiation did light begin its reign. That occurred during the Epoch of Reionization.
Universe Today recently explored the importance of studying impact craters and what they can teach us about finding life beyond Earth. Impact craters are considered one of the many surface processes—others include volcanism, weathering, erosion, and plate tectonics—that shape surfaces on numerous planetary bodies, with all of them simultaneously occurring on Earth. Here, we will explore how and why planetary scientists study planetary surfaces, the challenges faced when studying other planetary surfaces, what planetary surfaces can teach us about finding life, and how upcoming students can pursue studying planetary surfaces, as well. So, why is it so important to study planetary surfaces throughout the solar system?
There’s overwhelming evidence that Mars was once wet and warm. Rivers flowed across its surface and carved intricate channel systems revealed by our orbiters. Expansive oceans even larger than Earth’s may have covered a third of its surface. Then something happened: Mars lost its atmosphere, cooled down, and surface water disappeared.
In Dante Alighieri’s epic poem The Divine Comedy, the famous words “Abandon all hope, ye who enter here” adorn the gates of hell. Interestingly enough, Dante’s vision of hell is an apt description of what conditions are like on Venus. With an average temperature of 450 °C (842 °F), atmospheric pressures 92 times that of Earth, and clouds of sulfuric acid rain to boot, Venus is the most hostile environment in the Solar System. It is little wonder why space agencies, going all the way back to the beginning of the Space Age, have had such a hard time exploring Venus’ atmosphere.
Our galaxy is filled with magnetic fields. They come not just from stars and planets, but from dusty stellar nurseries and the diffuse hydrogen gas of interstellar space. We’ve long known of this galactic magnetic field, but mapping it in detail has posed a challenge. Now a new study gives us a detailed 3-dimensional map of these fields, with a few surprises.
Solar power is a booming industry right now as we all strive to run our lives with minimum carbon footprint. Solar is a relatively easy way to get clean electricity but of course we are limited to the hours then Sun is above the horizon. Solar panels in space have been muted before but the costs and technology to transmit power to Earth is prohibitive. An alternative approach has been explored by a team of engineers who have been looking at the possibility of deploying giant reflectors into space.
After analyzing the temperature data from 2023, NASA has concluded that it was the hottest year on record. This will surprise almost nobody. If you live in one of the regions stricken by drought, forest fires, or unusually powerful weather, you don’t need NASA to confirm that the planet is warming.
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