Universe Today

February 19, 2024February 19, 2024 by Brian Koberlein

Gravastars are an Alternative Theory to Black Holes. Here's What They'd Look Like

Artist view of a black hole in the middle of solar system. Credit: Petr Kratochvil/PublicDomainPictures CC0

One of the central predictions of general relativity is that in the end, gravity wins. Stars will fuse hydrogen into new elements to fight gravity and can oppose it for a time. Electrons and neutrons exert pressure to counter gravity, but their stability against that constant pull limits the amount of mass a white dwarf or neutron star can have. All of this can be countered by gathering more mass together. Beyond about 3 solar masses, give or take, gravity will overpower all other forces and collapse the mass into a black hole.

February 19, 2024February 19, 2024 by David Dickinson

European Satellite ERS-2 to Reenter Earth’s Atmosphere This Week

One of the largest reentries in recent years, ESA’s ERS-2 satellite is coming down this week.

After almost three decades in orbit, an early Earth-observation satellite is finally coming down this week. The European Space Agency’s (ESA) European Remote Sensing satellite ERS-2 is set to reenter the Earth’s atmosphere on or around Wednesday, February 21^st.

February 19, 2024February 19, 2024 by Mark Thompson

Look at How Much the Sun Has Changed in Just Two Years

Image of the Sun from Solar Orbiter (left Feb 2021 and right Oct 2023)

The solar cycle has been reasonably well understood since 1843 when Samuel Schwabe spent 17 years observing the variation of sunspots. Since then, we have regularly observed the ebb and flow of the sunspots cycle every 11 years. More recently ESA’s Solar Orbiter has taken regular images of the Sun to track the progress as we head towards the peak of the current solar cycle. Two recently released images from February 2021 and October 2023 show how things are really picking up as we head toward solar maximum.

February 19, 2024February 19, 2024 by Mark Thompson

What are the Differences Between Quasars and Microquasars?

Quasars are fascinating objects; supermassive black holes that are actively feasting on material from their accretion disks. The result is a jet that can outshine the combined light from the entire galaxy! There are smaller blackholes too that are the result of the death of stars and these also sometimes seem to host accretion disks and jets just like their larger cousins. We call these microquasars and, whilst there are similarities between them, there are differences too.

February 19, 2024February 22, 2024 by Alan Boyle

Odysseus Moon Lander Sends Back Selfies With Earth in the Picture

Odysseus lander selfie with Earth in background — A fisheye photo captured by a camera aboard the Odysseus lander shows the lander itself with Earth in the background. (Credit: Intuitive Machines)

Intuitive Machines’ Odysseus lander has beamed back a series of snapshots that were captured as it headed out from the Earth toward the moon, and one of the pictures features Australia front and center. The shots also show the second stage of the SpaceX Falcon 9 rocket that launched the spacecraft, floating away as Odysseus pushed onward.

February 18, 2024February 18, 2024 by Brian Koberlein

Even Eris and Makemake Could Have Geothermal Activity

Illustration of the icy dwarf planets Eris and Makemake. Credit: Southwest Research Institute

Whether or not you agree that Pluto isn’t a planet, in many ways, Pluto is quite different from the classical planets. It’s smaller than the Moon, has an elliptical orbit that brings it closer to the Sun than Neptune at times, and is part of a collection of icy bodies on the edge of our solar system. It was also thought to be a cold dead world until the flyby of New Horizons proved otherwise. The plucky little spacecraft showed us that Pluto was geologically active, with a thin atmosphere and mountains that rise above icy plains. Geologically, Pluto is more similar to Earth than the Moon, a fact that has led some to reconsider Pluto’s designation as a dwarf planet.

February 17, 2024February 17, 2024 by Laurence Tognetti

There’s One Last Place Planet 9 Could Be Hiding

Artist's illustration of Planet Nine with the Sun and orbit of Neptune (ring) in the distance. (Credit: ESO/Tomruen/nagualdesign)

A recently submitted study to The Astronomical Journal continues to search for the elusive Planet Nine (also called Planet X), which is a hypothetical planet that potentially orbits in the outer reaches of the solar system and well beyond the orbit of the dwarf planet, Pluto. The goal of this study was to narrow down the possible locations of Planet Nine and holds the potential to help researchers better understand the makeup of our solar system, along with its formation and evolutionary processes. So, what was the motivation behind this study regarding narrowing down the location of a potential Planet Nine?

February 17, 2024February 17, 2024 by Scott Alan Johnston

China's Chang'e-8 Mission Will Try to Make Bricks on the Moon

Artist's impression of Chang'e-8. Credit: CNSA.

The China National Space Administration (CNSA) has put out a call for international and industry partners to contribute science payloads to its Chang’e-8 lunar lander, set for launch to the Moon in 2028. The mission, which will involve a lander, a rover, and a utility robot, will be China’s first attempt at in-situ resource utilization on the Moon, using lunar regolith to produce brick-like building materials.

February 17, 2024February 17, 2024 by Matt Williams

Can the Gaia Hypothesis Be Tested in the Lab?

A new paper proposes an experimental setup that could test the classic Daisyworld model — a hypothesis of a self-regulating planetary ecosystem — in the lab via two synthetic bacterial strains. Credit: Victor Maull/Image Designer

During the 1970s, inventor/environmentalist James Lovelock and evolutionary biologist Lynn Margulis proposed the Gaia Hypothesis. This theory posits that Earth is a single, self-regulating system where the atmosphere, hydrosphere, all life, and their inorganic surroundings work together to maintain the conditions for life on the planet. This theory was largely inspired by Lovelock’s work with NASA during the 1960s, where the skilled inventor designed instruments for modeling the climate of Mars and other planets in the Solar System.

According to this theory, planets like Earth would slowly grow warmer and their oceans more acidic without a biosphere that regulates temperature and ensures climate stability. While the theory was readily accepted among environmentalists and climatologists, many in the scientific community have remained skeptical since it was proposed. Until now, it has been impossible to test this theory because it involves forces that work on a planetary scale. But in a recent paper, a team of Spanish scientists proposed an experimental system incorporating synthetic biology that could test the theory on a small scale.