Here is a problem that has been quietly gnawing at astronomers for decades.

The standard approach to detecting #life on other worlds involves scanning #exoplanet #atmospheres for #oxygen, #methane, and #ozone, whose presence is difficult to explain without #biology.

It's a clever idea, but it carries a hidden flaw. That entire shopping list was written by studying Earth. It is, inevitably, a search for life like us.

The list of ways that #chemistry alone can accidentally mimic these #biosignature gases is growing faster than the list of new ways to detect life.

Each new false positive scenario demands even more information about the #planet to rule it out, and there is a genuine question about whether that information can ever be gathered exhaustively.

But there is a solution.

#Assembly theory doesn't ask what #molecules are present in an #atmosphere. Instead, it asks how hard they were to make.

Every molecule can be assigned an assembly index, a minimum number of construction steps required to build it from basic #chemical building blocks.

Simple molecules are easy to assemble by chance, but truly complex ones, requiring many sequential steps, don't arise without something doing a great deal of deliberate selection.

That something would then be life itself.

#astrobiology #astronomy
https://phys.org/news/2026-03-life.html

Paper by Walker et al. (2026): https://arxiv.org/abs/2603.11086

Good idea: climate action to increase crop yields

https://airqualitynews.com/headlines/cleaner-air-from-climate-action-could-ease-hunger-risks/

Previous research has suggested that some climate mitigation measures – such as carbon pricing, expanding crops used for bioenergy and planting forests in new areas – might raise food prices and reduce the number of calories available worldwide. That could leave millions more people at risk of hunger.

However, those studies missed an important side effect: policies that cut greenhouse gases also reduce air pollutants that create ground-level ozone, including methane and nitrogen oxides.

Ground-level ozone is harmful to crops. It damages plants and reduces yields of key staple foods such as wheat, rice and maize. By lowering ozone pollution, climate policies can improve crop productivity and partly offset the economic pressures those policies place on food systems.

Full study: https://www.nature.com/articles/s43016-026-01322-3

#worldhunger #ozone #climateprotection #food #climate #pollution

☢️‘Without the ozone layer, the radiation that reaches us is comparable to the radiation from an atomic bomb.’

Reynier Peletier, astronomer at the UG, is worried about #SpaceX & Musk's plans to launch another million satellites in space.🛰️

Curious? Read more 👇
🔗 https://www.rug.nl/fse/news/matter-and-space/data-centres-in-space-threaten-astronomy-and-ozone-layer

🧪 #SciComm #ScienceNewsroom #astronomy #ozone #KapteynInstitute #astrophysics #physics #research #science #scientistsOnMastodon @universityofgroningen

Over the past few years, the number of #satellite launches has skyrocketed.

There are now nearly 15 000 active #satellites in orbit around the Earth, most of them part of mega-constellations in which each satellite has a service life of only a few years.

New satellites must be quickly launched as replacements. To avoid leaving old, dead satellites in Earth’s already-crowded low orbits, most satellite operators deliberately de-orbit them into Earth’s upper atmosphere.

That approach is now being taken to a vastly larger scale and there are implications for Earth’s #climate and #atmosphere.

Rocket launches already contribute to climate change and #ozone depletion.

Scaling them up to deploy a million aircraft-sized satellites would push upper-atmosphere heating and ozone loss far beyond previous estimates, with the steady burn-up of dead satellites compounding the impacts.

This is just a fraction of what is to come if planned mega-constellations go ahead. Operators worldwide have already asked for a combined total of over one million satellites.

The very smallest particles, finer than a human hair, can stay suspended in the atmosphere for years, contributing to ozone depletion and climate change.

A million satellites could mean that a teragram of alumina accumulates in the upper atmosphere – enough, alongside launch emissions, to significantly alter atmospheric chemistry and heating in dramatic ways we do not yet understand.

There is no public mandate for a single company in one country to make changes on that scale to the planet’s atmosphere.

#space #astronomy
https://theconversation.com/a-new-space-race-could-turn-our-atmosphere-into-a-crematorium-for-satellites-276366

🧪 The Ozone Success Story With a Complicated Ending

https://oilprice.com/Energy/Energy-General/The-Ozone-Success-Story-With-a-Complicated-Ending.html

#chemicals #environment #ozone #fgases #refrigerants #technology #safety

Space debris are contaminating our atmosphere at very high altitudes – and we don’t yet understand the effects.

https://skyandtelescope.org/astronomy-news/rocket-reentry-leaves-lithium-in-earths-upper-atmosphere/ via Sky&Telescope

#astronomy #lithium #atmosphere #starlink #pollution #ozone