And dolphins greet them...They have successfully made it back to Earth.
(100 kilometers per hour is roughly 62 miles per hour)
The thread for space cadets!
- Thread starter hobbsyoyo
- Start date
stfoskey12
Emperor of Foskania
I was more thinking about a minimum size. Should a rock 10 cm across orbiting a planet be considered a moon?
When Saturn has rings this must be the question. At 10 cm you are getting into the size of ring particles.
No. IMO you'd need to be able to plant your moonboots on it plus a flag to call it a moon at a minimum.
Does "plant your moonboots" mean enough gravity to significantly pull you down? That must rule out most, including Phobos were it is only 0.0057 m/s².
Slightly related:
Is not ultratraditionalist missing the Sun and the Moon?
Is dark energy getting weaker? Fresh data bolster shock finding
Physicists had long assumed that the elusive force has constant strength. But the latest results from a project to map the Universe’s expansion challenge this idea.
Fresh data have bolstered the discovery that dark energy, the mysterious force that makes galaxies accelerate away from each other, has weakened over the past 4.5 billion years.
The effect was first tentatively reported in April last year, but the latest results — presented on 19 March by the Dark Energy Spectroscopic Instrument (DESI) collaboration at a meeting of the American Physical Society in Anaheim, California — are based on three years’ worth of data-taking, versus one year for the results announced in 2024.
“Now I’m really sitting up and paying attention,” says Catherine Heymans, an astronomer at the University of Edinburgh, UK, and the Astronomer Royal for Scotland.
If the findings hold up, they could force cosmologists to revise their ‘standard model’ for the history of the Universe. The model has generally assumed that dark energy is an inherent property of empty space that does not change over time — a ‘cosmological constant’.
“The gauntlet has been thrown down to the physicists to explain this,” says Heymans.
Cosmic mapping
The DESI telescope is located at Kitt Peak National Observatory near Tucson, Arizona. It uses 5,000 robotic arms to point optical fibres at selected points where galaxies or quasars are located within its field of view. The fibres then deliver light to sensitive spectrographs that measure how much each object is redshifted — meaning the degree to which its light waves were stretched by the expansion of space on their way to Earth. Researchers can estimate an object’s distance using its redshift, to produce a 3D map of the Universe’s expansion history.
In that map, researchers then look at the density of galaxies to identify variations that are left over from sound waves called baryon acoustic oscillations (BAOs), which existed before stars began to form. Those variations have a characteristic scale that started out at 150 kiloparsecs (450,000 light years) in the primordial Universe and has been increasing with the cosmic expansion; they have now grown by a factor of 1,000 to 150 megaparsecs across — making them the largest known features in the current Universe.
By tracking the evolving size of BAOs, researchers can reconstruct how the Universe’s rate of expansion has changed over the eons. Around 5 billion years ago, the expansion switched from decelerating to accelerating under the push of dark energy. Until last year, cosmology data were all consistent with dark energy being a cosmological constant — which meant that the Universe should continue to expand at an increasingly fast rate.
But the results of DESI’s latest analysis imply that the cosmic expansion is accelerating less now than it was in the past, which does not fit the assumption that dark energy is a cosmological constant. Instead, the data suggest that its energy density — the amount of dark energy per cubic metre of space — is now around 10% lower than it was 4.5 billion years ago.
Physicists had long assumed that the elusive force has constant strength. But the latest results from a project to map the Universe’s expansion challenge this idea.
Fresh data have bolstered the discovery that dark energy, the mysterious force that makes galaxies accelerate away from each other, has weakened over the past 4.5 billion years.
The effect was first tentatively reported in April last year, but the latest results — presented on 19 March by the Dark Energy Spectroscopic Instrument (DESI) collaboration at a meeting of the American Physical Society in Anaheim, California — are based on three years’ worth of data-taking, versus one year for the results announced in 2024.
“Now I’m really sitting up and paying attention,” says Catherine Heymans, an astronomer at the University of Edinburgh, UK, and the Astronomer Royal for Scotland.
If the findings hold up, they could force cosmologists to revise their ‘standard model’ for the history of the Universe. The model has generally assumed that dark energy is an inherent property of empty space that does not change over time — a ‘cosmological constant’.
“The gauntlet has been thrown down to the physicists to explain this,” says Heymans.
Cosmic mapping
The DESI telescope is located at Kitt Peak National Observatory near Tucson, Arizona. It uses 5,000 robotic arms to point optical fibres at selected points where galaxies or quasars are located within its field of view. The fibres then deliver light to sensitive spectrographs that measure how much each object is redshifted — meaning the degree to which its light waves were stretched by the expansion of space on their way to Earth. Researchers can estimate an object’s distance using its redshift, to produce a 3D map of the Universe’s expansion history.
In that map, researchers then look at the density of galaxies to identify variations that are left over from sound waves called baryon acoustic oscillations (BAOs), which existed before stars began to form. Those variations have a characteristic scale that started out at 150 kiloparsecs (450,000 light years) in the primordial Universe and has been increasing with the cosmic expansion; they have now grown by a factor of 1,000 to 150 megaparsecs across — making them the largest known features in the current Universe.
By tracking the evolving size of BAOs, researchers can reconstruct how the Universe’s rate of expansion has changed over the eons. Around 5 billion years ago, the expansion switched from decelerating to accelerating under the push of dark energy. Until last year, cosmology data were all consistent with dark energy being a cosmological constant — which meant that the Universe should continue to expand at an increasingly fast rate.
But the results of DESI’s latest analysis imply that the cosmic expansion is accelerating less now than it was in the past, which does not fit the assumption that dark energy is a cosmological constant. Instead, the data suggest that its energy density — the amount of dark energy per cubic metre of space — is now around 10% lower than it was 4.5 billion years ago.
I'm going with just space, if you want stick to the rock bring some glue.
The moon and sun are considered lights in the sky in the tradtional view. Might be do to them being the only resolvable objects to the naked eye. Venus might come close but afaik that was only recognized in the Renaissence due to it showing phases.
The moon and sun are considered lights in the sky in the tradtional view. Might be do to them being the only resolvable objects to the naked eye. Venus might come close but afaik that was only recognized in the Renaissence due to it showing phases.
Nasa rover discovers largest organic compounds yet found on Mars
Nasa’s Curiosity rover has found the largest organic compounds ever seen on Mars, raising tantalising questions about whether life emerged on the red planet billions of years ago.
The compounds were detected in a 3.7bn-year-old rock sample collected in Yellowknife Bay, an ancient Martian lakebed that harboured all the necessary ingredients for life in the planet’s warmer, wetter past.
Tests onboard the rover found that the rock contained long-chain alkanes, organic molecules thought to be remnants of fatty acids. The compounds can be made by lifeless chemical reactions, but are crucial constituents of cell membranes in all living organisms on Earth.
The researchers do not claim to have found a biosignature – a “smoking gun” indicating life was once present – but one expert said the material represented the best chance that scientists had ever had for identifying remains of life on Mars.
“These molecules can be made by chemistry or biology,” said Dr Caroline Freissinet, an analytical chemist who led the research at the Atmospheres and Space Observations Laboratory in Guyancourt, near Paris. “If we have long-chain fatty acids on Mars, those could come – and it’s only one hypothesis – from membrane degradation of cells present 3.7bn years ago.”
For the latest study, Freissinet and her colleagues developed a new procedure to test more of the sample drilled from the mudstone. This time, Curiosity detected much larger organics, namely decane, undecane and dodecane.
Further analysis of the organics only deepened the intrigue. When organisms on Earth make fatty acids, the compounds tend to contain more even numbers than odd numbers of carbon atoms. This is because some enzymes build fatty acids by adding two carbon atoms at a time. The scientists saw hints of this in the Martian organics, too. “Cumberland is teasing us,” Freissinet said. “The one in the middle with 12 carbons is more abundant than the other two. We have the same trend on Mars, but a trend drawn from three molecules is not a real trend. Still, it’s very intriguing.”
Nasa’s Curiosity rover has found the largest organic compounds ever seen on Mars, raising tantalising questions about whether life emerged on the red planet billions of years ago.
The compounds were detected in a 3.7bn-year-old rock sample collected in Yellowknife Bay, an ancient Martian lakebed that harboured all the necessary ingredients for life in the planet’s warmer, wetter past.
Tests onboard the rover found that the rock contained long-chain alkanes, organic molecules thought to be remnants of fatty acids. The compounds can be made by lifeless chemical reactions, but are crucial constituents of cell membranes in all living organisms on Earth.
The researchers do not claim to have found a biosignature – a “smoking gun” indicating life was once present – but one expert said the material represented the best chance that scientists had ever had for identifying remains of life on Mars.
“These molecules can be made by chemistry or biology,” said Dr Caroline Freissinet, an analytical chemist who led the research at the Atmospheres and Space Observations Laboratory in Guyancourt, near Paris. “If we have long-chain fatty acids on Mars, those could come – and it’s only one hypothesis – from membrane degradation of cells present 3.7bn years ago.”
For the latest study, Freissinet and her colleagues developed a new procedure to test more of the sample drilled from the mudstone. This time, Curiosity detected much larger organics, namely decane, undecane and dodecane.
Further analysis of the organics only deepened the intrigue. When organisms on Earth make fatty acids, the compounds tend to contain more even numbers than odd numbers of carbon atoms. This is because some enzymes build fatty acids by adding two carbon atoms at a time. The scientists saw hints of this in the Martian organics, too. “Cumberland is teasing us,” Freissinet said. “The one in the middle with 12 carbons is more abundant than the other two. We have the same trend on Mars, but a trend drawn from three molecules is not a real trend. Still, it’s very intriguing.”
There could be a nova tomorrow
We have been waiting for T Coronae Borealis to blow after 80 years, and someone reckons it could be tomorrow:
To better pinpoint the next eruption date, the astronomer behind the 2024 study, Jean Schneider of the Paris Observatory, combined the previous explosion dates with the orbital dynamics of the star system. The researcher found that the nova eruptions occurred at intervals that were an exact multiple of the star system’s orbital period—meaning the explosions happened after a specific number of orbits the stars completed around each other. Rather than relying on the behavior of the star system, the paper suggests that T CrB explodes once every 128 orbits, with each orbital period being roughly 227 days.
Based on these calculations, the nova is set to take place on March 27. Should it fail to explode on Thursday, Schneider lists two subsequent dates: November 10, 2025 and June 25, 2026. In his paper, he also predicted August 12, 2024, which we can now obviously rule out. To be clear, Schneider is strictly running the numbers; his paper does not take into account the physics of how or why the eruption happens. It’s a one-dimensional approach, so his predictions could be way off—but wow would that ever be neat if the Blaze Star erupts according to his unusually strict timeline.
We have been waiting for T Coronae Borealis to blow after 80 years, and someone reckons it could be tomorrow:
To better pinpoint the next eruption date, the astronomer behind the 2024 study, Jean Schneider of the Paris Observatory, combined the previous explosion dates with the orbital dynamics of the star system. The researcher found that the nova eruptions occurred at intervals that were an exact multiple of the star system’s orbital period—meaning the explosions happened after a specific number of orbits the stars completed around each other. Rather than relying on the behavior of the star system, the paper suggests that T CrB explodes once every 128 orbits, with each orbital period being roughly 227 days.
Based on these calculations, the nova is set to take place on March 27. Should it fail to explode on Thursday, Schneider lists two subsequent dates: November 10, 2025 and June 25, 2026. In his paper, he also predicted August 12, 2024, which we can now obviously rule out. To be clear, Schneider is strictly running the numbers; his paper does not take into account the physics of how or why the eruption happens. It’s a one-dimensional approach, so his predictions could be way off—but wow would that ever be neat if the Blaze Star erupts according to his unusually strict timeline.
Partial Solar Eclipse on 29. März 2025
Partial solar eclipse on Samstag, 29. März 2025: Where and when is the Sun eclipse visible? Shadow map, animation, and local times.
www.timeanddate.com
What created this unusual hole in Mars?Actually, there are numerous holes pictured in this Swiss cheese-like landscape, with all-but-one of them showing a dusty, dark, Martian terrain beneath evaporating, light, carbon dioxide ice. The most unusual hole is on the upper right, spans about 100 meters, and seems to punch through to a lower level.Why this hole exists and why it is surrounded by a circular crater remains a topic of speculation, although a leading hypothesis is that it was created by a meteor impact. Holes such as this are of particular interest because they might be portals to lower levels that extend into expansive underground caves.If so, these naturally occurring tunnels are relatively protected from the harsh surface of Mars, making them relatively good candidates to contain Martian life.These pits are therefore also prime targets for possible future spacecraft, robots, and even human interplanetary explorers.
stfoskey12
Emperor of Foskania
Thoughts on K2-18b?
www.nytimes.com
A few key quotes from the article:
Astronomers Detect a Possible Signature of Life on a Distant Planet
Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable.
A few key quotes from the article:
This is the same as we were excited about in 2023, published in a good jornal. I think the question marks are the same as then, it could be life but it could be so many other things.Thoughts on K2-18b?
Astronomers Detect a Possible Signature of Life on a Distant Planet
Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable.
A few key quotes from the article:
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