Space

edit: title was modified to call attention to the discussion in the comments

The article is by Rajendra Gupta, Adjunct professor Physics @ L’Université d’Ottawa/University of Ottawa

First few lines:

Do constants of nature — the numbers that determine how things behave, like the speed of light — change over time as the universe expands? Does light get a little tired travelling vast cosmic distances? It was believed that dark matter and dark energy explained these cosmological phenomena, but recent research indicates that our universe has been expanding without dark matter or dark energy.

Doing away with dark matter and dark energy resolves the “impossible early galaxy problem,” that arises when trying to account for galaxies that do not adhere to expectations regarding to size and age. Finding an alternative to dark matter and energy that complies with existing cosmological observations, including galaxy distribution, is possible.

“We need to consider alternatives to dark matter that better explain cosmological observations” (see comments for discussion)

cross-posted from: https://lemmy.ml/post/17634058

An asteroid the size of a football stadium threaded the needle between Earth and the moon Saturday morning — the second of two astronomical near misses in three days. Near miss, in this case, is a relative term: Saturday's asteroid, 2024 MK, came within 180,000 miles of Earth. On Thursday, meanwhile, asteroid 2011 UL21 flew within 4 million miles.

But the Saturday passage of 2024 MK — which scientists discovered only two weeks ago — coincides with a sobering reminder of threats from space. Sunday is Asteroid Day, the anniversary of the 1908 explosion of a rock from space above a Russian town — the sort of danger that, astronomers warn, is always lurking as the Earth hurtles through space... In 2013, for instance, an asteroid about 62 feet across that broke apart nearly 20 miles above Siberia released 30 times as much energy as the atomic bomb that hit Hiroshima. While most of the impact energy was absorbed by the atmosphere, the detonation triggered a shock wave that blew out windows and injured more than a thousand people.

The article points out that if Saturday's asteroid had hit earth, the impact would have "the equivalent impact energy in the hundreds of megaton approaching a gigaton," Peter Brown of Canada's Western University told the Canadian Broadcasting Service. (For comparison, most hydrogen bombs are in the 50-megaton range.) Brown said "It's the sort of thing that if it hit the east coast of the U.S., you would have catastrophic effects over most of the eastern seaboard. But it's not big enough to affect the whole world."

Meanwhile, the article adds that last Thursday's asteroid — "while it was comfortably far out in space" — was the size of Mt. Everest. "At 1.5 miles in diameter, that asteroid was about a quarter the size of the asteroid that struck the earth 65 million years ago, wiping out all dinosaurs that walked, as well as the majority of life on earth." But the risk of a collision like that "is very, very low." NASA has estimated that a civilization-ending event (like the collision of an asteroid the size of Thursday's with the Earth) should only happen every few million years. And such an impact from an asteroid half a mile in diameter or bigger will be almost impossible for a very long time, according to findings published last year in The Astronomical Journal.

NASA's catalog of large and dangerous objects like 2011 UL21 is now 95 percent complete, MIT Technology Review reported.

Scott Manley video, looks like the hold down claps may have ripped the bottom off the booster, allowing it to take off.

cross-posted from: https://lemmy.ml/post/17489886

NASA and Boeing officials pushed back Friday on headlines that the commercial Starliner crew capsule is stranded at the International Space Station but said they need more time to analyze data before formally clearing the spacecraft for undocking and reentry.

Summ:

• The James Webb Space Telescope (JWST) has discovered the most distant galaxy ever confirmed, named JADES-GS-z14-0, which appears as it existed just 290 million years after the Big Bang.

• The discovery of this surprisingly luminous and massive early galaxy challenges theories about how galaxies formed in the cosmic dawn

• JWST has been repeatedly breaking its own records for the most distant galaxies since beginning operations in 2022

more about:

https://www.bbc.com/news/articles/cjeenyw8rd2o

https://webbtelescope.org/contents/early-highlights/nasas-james-webb-space-telescope-finds-most-distant-known-galaxy

Personally, I find Brown Dwarfs to be absolutely fascinating. An object that isn't quite a planet and isn't quite a star, but something in between.

What would one even look like? Would it look like a gas giant that's glowing red, along with swirls of gas in its atmosphere like Jupiter? Or would it resemble a star and have a fiery surface like the sun? I prefer to imagine them as glowing gas giants but I don't know how realistic that is.

Gas giants in general are fascinating to me as well, I really hope we send a probe into one of the gas giants with a camera before I die. I'd absolutely love to see what it looks like inside a gas giants atmosphere before the probe gets crushed by the increasing pressure as it descends.