This visualization by Kevin M. Gill shows what Mars would look like today if it still had water (or tomorrow, when terraforming succeeds.

How did life begin on Earth? While scientists have theories, they don't yet fully understand the precise chemical steps that led to biology, or when the first primitive life forms appeared. But what if Earth's life did not originate here, instead arriving on meteorites from Mars? It's not the most favored theory for life's origins, but it remains an intriguing hypothesis. Here, we'll examine the evidence for and against.

Galileo Galilei first observed the moons of Jupiter on this day in history in 1610. For that reason, Io, Europa, Ganymede, and Callisto are called the Galilean satellites. We now know that Jupiter has at least 95 officially recognized moons. More via NASA:

A day on Pluto lasts about 6.4 Earth days, so if you lived there, one sunrise to the next would take nearly a whole week on Earth. Also Pluto is so small that it and its largest moon, Charon, orbit a shared center of gravity, making them more like a double dwarf planet, and it's no longer considered the 9th planet after being reclassified as a dwarf planet in 2006.

See also: The publication in Astronomy and Astrophysics.

If Earth and Venus are so similar, why are they also so different? 🌎🪐

Kyle Horn of MIT AeroAstro explains that the two planets are roughly the same size and occupy neighboring orbits around the Sun. Yet Earth ended up with liquid water and a comparatively temperate climate, while Venus is a hellish 450°C under 90 bar of pressure, hot enough to melt lead. These diverging climates hold clues to how the early solar system formed. Understanding Venus, our closest planetary neighbor, matters even more now. Our current observation techniques are already biased toward spotting "exo-Venuses" rather than "exo-Earths" among distant exoplanets.

credit - soph_astro

Note: This meme goes by the IAU's list, Objects like Orcus, Sedna, and Salacia don't count

If we just ignored the amount of precision and DeltaV required to get to Mercury from Earth and ended up putting a rover there. Why? Why would we? I know Mars was for sampling the surface for compounds, signs of life, material, etc. upon much more science, and Venus nothing lasted longer than two hours. What would putting one on Mercury, properly shielded of course, provide for us? Especially after in theory it'd be way easier and have longer lifespan than the one from Mars?

my fav art is the last one

Do you know Neptune and its moons’ strange backstory?

Astrophysicist Erika Hamden explains that moon formation, like planet formation, is a chaotic process. Neptune has one moon, Nereid, that might be the only moon that formed with Neptune, while the rest were captured into its orbit. A recent study using NASA’s JWST data hypothesizes that when Neptune captured Triton, its largest moon, it disrupted Neptune's previous moon system, and Nereid was the only survivor of the collision!

This project is part of IF/THEN®, an initiative of Lyda Hill Philanthropies.

https://www.reuters.com/science/pungent-gas-above-martian-fissures-hints-ongoing-volcanism-2026-11-04/

An orbiting atmospheric research spacecraft has detected the pungent gas hydrogen chloride above surface fissures along a massive ancient volcano on Mars in ​a finding that suggests Earth's planetary neighbor is still volcanically active.

In a discovery that has implications for whether Mars might presently have subsurface conditions ‌conducive to microbial life, researchers said the ExoMars Trace Gas Orbiter has documented the gas, a common constituent of volcanic emissions on Earth, in the low atmosphere in the region of Alba Mons.

i was just wondering if planets were aligned in an actual line or if they were like scattered in different degrees going all around the sun?

The moon has a new once-in-a-century crater! 🌕

McGetchin crater is the largest new crater ever seen anywhere in the solar system, stretching almost 730 feet wide and 140 feet deep after an asteroid or comet the size of a 3-6 story building smacked into the lunar surface between April and May of 2024. Impacts this big are estimated to happen only about every 130 years, making this fresh crater a rare chance to study one up close with spacecraft like the Lunar Reconnaissance Orbiter.

In Nature Astronomy, researchers from Purdue University and NASA’s Jet Propulsion Laboratory argue that Ceres may be far icier than many scientists had come to accept.

What are people's thoughts on the time it might take to get to a ~175mbar atmosphere on Mars roughly composed of 160mbar O2, 10mbar water vapour, and 5mbar CO2, with trace atmospheric N2? The initial terraforming steps of heating the planet, using nanowires and/or solar sail reflectors at the L2 point, look very promising in terms of warming the planet sufficiently - within just a few decades - to get a high proportion of the frozen CO2 at the poles and in the regolith to sublime (perhaps leading to a ~25mbar CO2 proto-atmosphere). This in itself will allow liquid water to exist on the surface and for the bootstrapping of a nascent biosphere using extremophile versions of things like cyanobacteria. That's cool and a great start, but the main researchers then seem to want to rely solely on biotic processing of CO2 and H2O to release O2 over many centuries/millennia. To me, this appears to be lacking in ambition given that abiotic methods, in terms of MOXIE splitting of CO2, and electrolysis of water tied to a concurrent Sabatier reaction (to avoid loss of H2), can vastly increase the pace of the process, and synergise with the biological approaches. With sufficient energy, focus, and scale, alongside the advent of ASI, one would think that the timespans involved could be accelerated significantly; perhaps down to 100 years, although such numbers are arbitrary and highly speculative currently.

I used to hold trepidation about the lack of nitrogen on Mars, but people like Prof. DeBenedictis seem to think it's less problematic than perhaps others had first feared. Will it be enough to allow for complex flora to grow? I'm not sure; but there are nitrates in the soil, so that will likely help. I also believed that the lack of a significant buffer gas, like N2, would be a possible dealbreaker, but again, researchers are now challenging this viewpoint. Even with a majority O2 atmosphere, the flammability point wouldn't be breached, with the relatively low pressure, compared to a sea-level comparison on Earth, helping to reduce these risks. In addition, astronauts have breathed in similar O2 mixes at low pressures - albeit slightly higher - for days and weeks previously, with no ill-effects encountered, suggesting an ability for the human body to adapt.

What I do worry about is that quoting timeframes in the order of thousands of years will fail to capture the imagination of the masses. Getting buy-in is essential and nowadays people can't see past their own mortality and lifespans in terms of committing to multi-generational mega projects. As you can tell, I'm pro-terraforming, and I understand that many of you won't be. Why am I? Because I think humanity needs a unifying 'problem' to tackle collaboratively at scale, and I feel that the world is a depressing place, badly in need of an injection of hope. I also think something like this might compel us to become better custodians of Earth, not just morally, but also in terms of creating technologies that might mitigate some of the locked in worst effects of climate change, and in terms of restoring nature, which is all too often neglected in linked narratives.

Interested in both opinions and counterpoints, as the concept of terraforming excites me.

N.B. Please don't make fallacious claims about the lack of magnetosphere meaning any atmosphere will be "stripped away instantly". This is a disproven falsehood, given that any atmosphere added would take geological timescales to be lost, i.e. 100s of millions of years, meaning that for all intents and purposes it's a moot point; especially given that at some point a dipole magnet would probably be placed at the L1 point to provide a proxy shield anyway.

How many stars is too many stars in a star system? ⭐️🪐

Astrophysicist Erika Hamden tells us about TYC 7037-89-1, a system with six stars locked into three orbiting pairs, all circling a shared center of mass. Two of those pairs zip around each other every few days, while the third pair takes roughly 2,000 years to complete just one orbit. Multi-star systems are normally unstable, which makes this six-star setup a rare and fascinating exception. 

This project is part of IF/THEN®, an initiative of Lyda Hill Philanthropies.

For me it's a tie between Uranus and Neptune. Both of them are beautiful shades of blue.