Our solar system has had a chaotic past. Earth and the other planets are now in stable orbits, but while they were forming they experienced drastic location shifts. Jupiter was likely much closer to the Sun than it is now, and its shift not only shifted other planets but also cleared the solar system of debris, tossing much of it to the Oort Cloud.
Every large galaxy in the nearby universe contains a supermassive black hole at its core. The mass of those black holes seems to have a relationship to the mass of the host galaxies themselves. But estimating the masses of more distant supermassive black holes is challenging. Astronomers extrapolate from what we know about nearby galaxies to estimate distant black hole masses, but it’s not a perfectly accurate measurement.
It’s a strange, eerie-looking place. Carbon dioxide gas appears… and disappears in cycles and bursts throughout the year. It’s how our planet would look if we could detect carbon dioxide (CO2) with our eyes. Scientists at NASA’s Global Modeling and Assimilation Office made computer animations of its presence in our atmosphere. Those videos show an almost-alien view of Earth under the influence of this gas.
Earth is, in many ways, a water world. Around two-thirds of its surface is covered in water, and the oceans that provide that cover make up over 96% of all water on Earth, according to the US Geological Survey. Glaciers and ice caps make up another 1.74%, but groundwater is the third most plentiful source at 1.69% of all water available on Earth. That’s an astonishing 23.4 million cubic kilometers of the stuff, dwarfing the mere 176,000 cubic kilometers contained in all the lakes in the world. But that does not mean the total amount of groundwater is unlimited, and removing it can have a lasting impact on more than just the people who use it for bathing and drinking. A new study points to how humans pumping out groundwater impacts Earth’s rotation.
The first stars of the universe were very different than the stars we see today. They were made purely of hydrogen and helium, without heavier elements to help them generate energy in their core. As a result, they were likely hundreds of times more massive than the Sun. But some of the first stars may have been even stranger. In the early universe, dark matter could have been more concentrated than it is now, and it may have powered strange stellar objects known as dark stars.
Hot Jupiters are large gas planets that orbit their star closely. Unlike our Jupiter, which radiates more heat than it gets from the Sun, hot Jupiters get more heat from their star than from their interior. As a result, they can have a surface temperature of 1,000 K rather than the 160 K that Jupiter has. They are one of the more common types of exoplanets and the easiest type of exoplanet to discover.
ESA’s BepiColumbo continues its journey to Mercury by making another flyby … of Mercury! This is the third of six planned flybys of its destination planet, each of which gives the spacecraft a gravitational deceleration. Eventually, it’ll slow down enough to go into its final operational orbit.
The war in Ukraine has taken a terrible toll, and the damage extends far from the shifting battle lines. In addition to the many soldiers and civilians who’ve died, over 2.5 million children have been displaced within the country. The war has also exacerbated the problems of orphaned children, who are especially vulnerable in urban areas where the fighting has been most intense. Ensuring these children and their families can get adequate food and medical care is always challenging. Ensuring they have access to education and counseling services so their lives are not severely interrupted is even more so.
We in the Milky Way Galaxy are pretty lucky to have a fairly quiet central supermassive black hole in Sgr A*. It’s not loud and bright like an active galactic nucleus. It appears to be active for brief periods before going to sleep. Two hundred years ago, it “woke up” for about a year and a half and had a bite to eat.
The enormous undersea volcano that erupted in Tonga last year was record-breaking in many regards. It generated the highest-ever recorded volcanic plume, it triggered a sonic boom that circled the globe twice, and was the most powerful natural explosion in more than a century.
If you’ve ever seen a meteor shower, you know it can be an amazing sight. You watch the skies as every few moments there’s a streak of light. Sometimes bright and in your field of vision. Sometimes starting just out of the corner of your eye. Although a meteor can occur at any time, they tend to appear at certain times of the year, such as the Perseids of August, or the Orionids of October.
Plenty of news stories have focused on the danger posed by Kessler syndrome. In this condition, space is made inaccessible by a cloud of debris surrounding our planet that would destroy any further attempts to get into orbit. Therefore, plenty of companies have sprung up that problem to take care of the problem, from blasting derelict satellites with lasers to helping to refuel them; lots of business models have been created to capture this opportunity. One of the farthest along is Astroscale. This British start-up is tackling the problem with one of the more conventional techniques – linking up with an existing satellite to deorbit it. And recently, they released a promotional video for their new project – the ELSA-M.
The James Webb Space Telescope (JWST) continues to push the boundaries of astronomy and cosmology, the very job it was created for. First conceived during the 1990s, and with development commencing about a decade later, the purpose of this next-generation telescope is to pick up where Spitzer and the venerable Hubble Space Telescope (HST) left off – examining the infrared Universe and looking farther back in time than ever before. One of the chief objectives of Webb is to observe high-redshift (high-Z) galaxies that formed during Cosmic Dawn.
When astronomers talk about the “end states” of stellar evolution, several categories come to mind: black holes, neutron stars/pulsars, and white dwarfs. What happens if one star ends up in two of these states? That’s the case with a genre-breaking white dwarf pulsar called J191213.72-441045.1 (J1912-4410 for short). It’s part of a binary pair that includes a red dwarf star.
The TRAPPIST-1 system is easily the most exciting collection of exoplanets ever discovered by astronomers. The system contains seven rocky planets orbiting an ultracool red dwarf star 40 light-years from Earth. Several of the planets are in the star’s habitable zone.
FU Orionis is an unusual variable star. It was first seen as a magnitude 16 star in the early 1900s, but in the mid-1930s it rapidly brightened to a magnitude 9 star. The rapid brightening of a star was not unheard of, but in this case, FU Orionis did not fade to its original brightness. Since 1937 it has remained around magnitude 9, varying only slightly over time. For decades the mysterious star was thought to be unique, but in the 1970s similar stars were observed, and are now known as FU Orionis objects. Astronomers still had no real idea what could cause such a dramatic change, but a new study argues that it could be caused by a dying young planet.
There’s some potentially big news on the hunt for dark matter. Astronomers may have a handle on what makes this mysterious cosmic stuff: strange particles called “axions.”
Prediction is one of the hallmarks of scientific endeavors. Scientists pride themselves on being able to predict physical realities based on inputs. So it should come as no surprise that a team of scientists at Notre Dame has developed a theory that can be used to predict the existence of giant planets on the fringes of an exoplanetary system.
We’ve filed plenty of reports here at UT warning about the potential impact of Starlink and similar satellites on the field of astronomy. We’ve gone so far as to point out that the granddaddy of space-based telescopes – Hubble – has already had some of its images tarnished by passing Starlink satellites. However, SpaceX has been aware of the problem and is working to limit their product’s brightness. The recently launched Gen2 satellites seem to have made a significant step forward – research from a team of amateur astronomers finds that the new Gen2 Starlinks are more than 10x fainter than previous Gen1 iterations.
Gravitational wave astronomy currently can only detect powerful rapid events, such as the mergers of neutron stars or stellar mass black holes. We’ve been very successful in detecting the mergers of stellar mass black holes, but a long-term goal is to detect the mergers of supermassive black holes.
Measuring cosmic distances is challenging, and astronomers rely on multiple methods and tools to do it – collectively referred to as the Cosmic Distance Ladder. One particularly crucial tool is Type Ia supernovae, which occur in binary systems where one star (a white dwarf) consumes matter from a companion (often a red giant) until it reaches the Chandrasekhar Limit and collapses under its own mass. As these stars blow off their outer layers in a massive explosion, they temporarily outshine everything in the background.
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