Universe Today

June 15, 2023June 15, 2023 by Brian Koberlein

More Evidence of Massive First Generation Stars

Artist's rendition of massive, luminous first-generation stars in the Universe. When they died, their supernova explosions produced dust. Credit: NAOC

A few days ago I wrote about the search for Population III stars. These stars were the first stars of the universe. Giant beasts hundreds of times more massive than the Sun, composed only of hydrogen and helium. These massive stars would have been very short-lived, exploding as brilliant supernovae in less than a million years. But Population III stars were so massive, their supernovae were uniquely different from the ones we see today, so our best way to find evidence of them is to look for their supernova remnants. And a recent study published in Nature may have found some.

June 14, 2023June 14, 2023 by Matt Williams

A Day on Earth Used to Only Be 19 Hours

A full disk view of the Earth, courtesy of Meteosat-I 1. Credit: ESA/Meteosat

On Earth, a single solar day lasts 24 hours. That is the time it takes for the Sun to return to the same place in the sky as the day before. The Moon, Earth’s only natural satellite, takes about 27 days to complete a single circuit around our planet and orbits at an average distance of 384,399 km (~238,854.5 mi). Since time immemorial, humans have kept track of the Sun, the Moon, and their sidereal and synodic periods. To the best of our knowledge, the orbital mechanics governing the Earth-Moon system have been the same, and we’ve come to take them for granted.

But there was a time when the Moon orbited significantly closer to Earth, and the average day was much shorter than today. According to a recent study by a pair o researchers from China and Germany, an average day lasted about 19 hours for one billion years during the Proterozoic Epoch – a geological period during the Precambrian that lasted from 2.5 billion years to 541 million years ago. This demonstrates that rather than gradually increasing over time (as previously thought), the length of a day on Earth remained constant for an extended period.

June 14, 2023June 14, 2023 by Carolyn Collins Petersen

An Element Critical for (Earth) Life is Spewing out of Enceladus

Saturn's moon Enceladus sprays its salty sea out into space. Those plumes are rich in phosphates. (NASA/JPL/SSI/J. Major)

We really need to get back to Enceladus. Not to send people necessarily, although that would be nice. But, we need to get some more robotic missions out there. This moon is one of the most intriguing places in the solar system. Not only has it got oceans under that icy crust, but it’s spewing salty water out to space. Plus, that water seems to be rich in phosphates, which contain phosphorus, which is a building block of life.

June 14, 2023June 14, 2023 by Evan Gough

A White Dwarf is Starting to Crystallize into Diamond

An artist’s impression of crystallization in a white dwarf star. The twho known white dwarf pulsars may have interiors like this. Image credit: Mark Garlick / University of Warwick.

White dwarfs are the stellar remnants of stars like our Sun. They’re strange objects, and astrophysicists think their cores can crystallize into enormous diamonds. But they need to find more of these strange objects, and they need to know their ages, to understand how and when it happens.

June 14, 2023June 14, 2023 by Carolyn Collins Petersen

Curiosity Takes One Final Postcard Image of a Picturesque Valley Before Moving on to its Next Destination

A "postcard" from Mars Curiosity rover combines two images at two different times of day with a color overlay to show the different views. Courtesy NASA/JPL-Caltech — A "postcard" view from Mars Curiosity rover. It combines images from two different times of day with a color overlay to show how the view changes. Courtesy NASA/JPL-Caltech

The Mars rover Curiosity continues to make its way up the slopes of Mount Sharp on Mars. On April 8th, its navigation cameras snapped a pair of images—one in the morning and one in the afternoon. They show distinctly different lighting angles during a crisp Martian winter day. The images got combined with a color overlay to produce a fantastic “postcard” from the Red Planet.

June 13, 2023June 13, 2023 by Paul M. Sutter

Without Ozone, the Earth Might Get a Lot Colder

Clouds trace out the islands of the Caribbean Sea in this photo taken by an astronaut from inside the Cupola on the International Space Station. Credit NASA/NASA Earth Observatory.

The evolution of Earth’s climate contains many components. And new research has shown just how critical the ozone layer is to the surface temperature of the Earth. Without an ozone layer, our planet would be 3.5 Kelvin cooler.

June 13, 2023June 13, 2023 by Matt Williams

Astronauts Will Be Tracking Dust Into the Lunar Gateway. Is This a Problem?

Artist's impression of astronauts on the lunar surface, as part of the Artemis Program. Credit: NASA

Lunar regolith (aka. Moondust”) is a major hazard for missions heading to the Moon. It’s everywhere on the surface – 5 to 10 meters (~16.5 to 33 feet) in depth in some places – not to mention jagged and sticky! During the Apollo missions, astronauts learned how this dust adhered to everything, including their spacesuits. Worse, it would get tracked back into their Lunar Modules (LMs), where it stuck to surfaces and played havoc with electronics and mechanical equipment, and even led to long-term respiratory problems.

This is a major concern for the Artemis Program, which aims to establish a “sustained program of lunar exploration and development.” One of the key elements of this program is the Lunar Gateway, a lunar habitat that will orbit the Moon for a planned 15 years and facilitate long-term missions to the surface. The impact that regolith introduced by astronauts returning from the surface will have is not well understood. In a recent paper, a NASA-led team of researchers created a physics-based model to asses how regolith could impact the habitat over time.

June 12, 2023June 12, 2023 by Matt Williams

China is Trying to Stop its Boosters From Randomly Crashing Into Villages

Chang'e-5 launch — China's Long March 5 rocket sends the Chang'e-5 probe on the first leg of its mission to the moon and back. (CNSA / CLEP Photo)

China’s space program has advanced by leaps and bounds in a relatively short time. However, it has suffered some bad publicity in recent years due to certain “uncontrolled reentries” (aka. crashes). On multiple occasions, spent first stages have fallen back to Earth, posing a potential threat to populated areas and prompting backlash from NASA and the ESA, who claimed China was taking “unnecessary risks.” To curb the risk caused by spent first stages, China has developed a parachute system that can guide fallen rocket boosters to predetermined landing zones.

According to the Chinese Academy of Launch Vehicle Technology (CALT), which developed the system, the system was successfully tested on a Long March-3B (CZ-3B) rocket on Friday, June 9th. As they indicated in their statement, a review of the test data and an in-situ analysis of the debris showed that the parachute system helped narrow the range of the landing area by 80%. This could help pave the way for future parachute landing control technology applications, which could allow for controlled reentry, retrieval, and even reusability.

June 12, 2023June 13, 2023 by Paul M. Sutter

Meet Annie Jump Cannon, the “Harvard Computer” that Brought Order Out of Chaos

These Hubble Space Telescope images showcase two of the 19 galaxies analyzed in a project to improve the precision of the universe's expansion rate, a value known as the Hubble constant. The color-composite images show NGC 3972 (left) and NGC 1015 (right), located 65 million light-years and 118 million light-years, respectively, from Earth. The yellow circles in each galaxy represent the locations of pulsating stars called Cepheid variables. Credits: NASA, ESA, A. Riess (STScI/JHU)

In the early 20th century our understanding of stars was a complete and total disaster. It took the genius of Annie Jump Cannon, who was hired as a human computer, to create some order out of the chaos.

June 12, 2023June 12, 2023 by Carolyn Collins Petersen

Astronomers Have Figured Out Clever Tricks to Reduce the Impact of Satellite Trails

A long-exposure image of the Orion Nebula with a total exposure time of 208 minutes showing satellite trails in mid-December 2019. Credit: A. H. Abolfath

A clear sky is a prerequisite for most astronomers imaging the cosmos. However, with the proliferation of satellite trails, astronomers see a lot more streaks in their images. That’s particularly true for people using professional ground-based and orbiting telescopes. When Hubble Space Telescope opened its eye on the sky, there were less than 500 satellites orbiting our planet. Now, there are nearly 8,000 of them, leaving their mark across the sky.