Carl Sagan Institute

Here is M16, the Eagle Nebula! The photo was produced by three CAS members on June 25th, stacked from 184 x 30-second frames. 🔭

The exposures were taken using the 102-year-old f/15 Irving P. Church 12" Refractor at the Fuertes Observatory, stacked in Siril and post-processed in Photoshop.

Here is Messier 17, the Omega or Swan Nebula, photographed by members of the Cornell Astronomical Society this Tuesday evening (6/24/25)! The images were taken through the 12" f/15 Irving P. Church Refractor at the Fuertes Observatory.

This is 124 x 30-second frames, stacked in Siril.

And after a finally clear evening (with no camera issues) of observing, here is the Cornell Astronomical Society's latest photo of M51, the Whirlpool Galaxy!

This is 11 3-minute exposures, stacked, taken through the Irving P. Church 12-inch refractor at the Cornell University Fuertes Observatory.

Another image (Pillars of Creation in the Eagle Nebula) taken this week with the Irving Porter Church Refractor at Fuertes Observatory, Cornell University. Astronomy has come a long way in the 100 years since this telescope was built, but the grainy images have their charm, too! Taken by Ben Jacobson-Bell, Gillis Lowry, and Marquice Sanchez-Fleming.

Recent drone view of Rubin! Credit: RubinObs/NOIRLab/SLAC/NSF/DOE/AURA/T. Matsopoulos

Rubin is a massive step forward in space science—especially when see how far astronomy has come over the centuries. We at the Carl Sagan Institute are incredibly excited!

What type of object do you most want to see with Rubin? Let us know! ✨✨✨

Lagoon Nebula through the 12" Irving Porter Church Memorial Refractor Telescope. Taken by Ben Jacobson-Bell, Gillis Lowry, Marquice Sanchez-Fleming, and Shane Kuo on 6/24/25. 49 x 30-second frames stacked using Siril, and post-processed with Photoshop.

Trifid Nebula through the 12" Irving P. Church Refractor. Taken by Marquice Sanchez-Fleming on 6/24/25. Later stacked 26 x 1-minute frames by Ben Jacobson-Bell, Gillis Lowry, and Marquice Sanchez-Fleming using Siril, and post-processed with Photoshop.

Lagoon Nebula image (lower) and Trifid Nebula image (upper) taken by the Cornell Astronomical Society against Rubin's massive field of view! Image credit: Andrew Lewis for comparison gif; Ben Jacobson-Bell, Gillis Lowry, and Marquice Sanchez-Fleming for astrophotography.

Students and astronomy researchers in the Cornell Astronomical Society took images with the 102-year-old telescope this week of the same sky. Our telescope is 15 feet long—decent for telescopes of that day—and still takes up a tiny fragment of Rubin's view.

(But hey, we love our old scope, too)!

Rubin's view of the Lagoon and Trifid nebulae.

The deep field view swarming with stars and galaxies is the kind of image Rubin can produce in one night via a "mosaic"—stitching together multiple images. But if Rubin focuses on one patch of the sky rather than taking a mosaic, the result is still huge:

JWST's infrared M61 against Rubin's deep field view in visible light.

Hubble's visible-light M61 against Rubin's visible-light deep field view.

(Here's a close-up on M61 with the Hubble Space Telescope and with JWST against the Rubin image)!

Can you find where we've overlaid a JWST image? Hint: it's a galaxy (M61), taken in infrared light, in contrast to Rubin's visible light. This comparison gives an idea of the sheer scale of Rubin—it got this entire image in one night!—and the difference in types of images each spacecraft takes.

The diameter of the James Webb Space Telescope's mirror is seven feet smaller than Rubin, but they're also very different instruments: JWST sees mostly in infrared light, while Rubin sees light visible to our own eyes. JWST also doesn't have to worry about Earth's atmosphere interfering with data.

Rubin gazes upward with a primary mirror nearly 28 feet across (8.4 meters) and a camera 12 feet wide (3.65 meters) Credit: RubinObs/NSF/DOE/NOIRLab/SLAC/AURA/W. O'Mullane

In a single night, Rubin generates 1000 images of 3.2 billion pixels each—20 terabytes of data.

In the next decade, Rubin will find 20 billion galaxies, 17 billion stars, 10 million supernovae, and 6 million Solar System objects (including five times the number of asteroids ever found)!

0.05% of the 10 billion galaxies Rubin will discover in the next decade. Every corner of the sky holds a star or galaxy, some of which were simply too far away, too dim, to be seen before now. Rubin bridges the vastness.

Have you seen the Rubin Observatory's first images?

Rubin has the largest digital camera in the world, and it's ready to revolutionize astronomy! Over the next decade, it will discover 2000x MORE galaxies than the 10 million shown below.

Let's explore how its images compare to other telescopes 🔭

Thank you to former CSI researcher Dr. Ryan MacDonald @distantworlds.space for the insightful presentation at CSI's coffee hour last week!

Dr. MacDonald's team has re-analyzed earlier data, finding no evidence for life on K2-18 b: arxiv.org/abs/2501.18477

Read more below!

Action Center Whether it's advocating, teaching, inspiring, or learning, you can do something for space, right now. Let's get to work.

*** If you’d like to support the search for life, take just one minute to urge American representatives to support NASA science. Slashing NASA’s budget in half would make these scientific discoveries near impossible. ***

www.planetary.org/action-center

False positives are natural in the search for life. For now, as always, we’re staying skeptical.

Evidence for Abiotic Dimethyl Sulfide in Cometary Matter Technological progress related to astronomical observatories such as the recently launched James Webb Space Telescope (JWST) allows searching for signs of life beyond our Solar System, namely in the f...

There is also evidence that dimethyl sulfide could be found in comets, and perhaps the clouds of gas and dust that eventually form stars.

arxiv.org/abs/2410.08724
iopscience.iop.org/article/10.3...

If dimethyl sulfide really is present, then we should examine all possible explanations before settling on the most likely scenario. Could it arise from sources other than life? The composition of ocean worlds is far from Earth-like; there may be unstudied interactions between its chemicals.

A diagram depicting "habitable zone" boundaries (where liquid water may exist on a rocky planet's surface) across star type. Earth is plotted alongside 42 exoplanets with radii less than 2 times that Earth, or masses less than 5 times that of Earth, making them potentially rocky worlds in the habitable zone. The optimistic limits come from Kopparapu et al. 2013, as does the rightmost boundary for the conservative habitable zone. The leftmost limit for the more conservative boundary comes from Ramirez and Kaltenegger 2017. K2-18 b is too large to be considered a rocky planet, and is not depicted here.

That’s not to say Madhusudhan et al.’s analysis isn’t important. A weak result—or lack of result—is still interesting, even if we can’t make bold conclusions. Weak results spur us to look further, and a lack of life narrows down which worlds may be hospitable.

Carbon dioxide would be evidence towards a liquid water ocean, since both water and carbon dioxide contain oxygen. Without evidence of such molecules, K2-18 b may be a gaseous planet instead of a water world.

A Comprehensive Reanalysis of K2-18 b's JWST NIRISS+NIRSpec Transmission Spectrum Sub-Neptunes are the most common type of planet in our galaxy. Interior structure models suggest that the coldest sub-Neptunes could host liquid water oceans underneath their hydrogen envelopes - some...

Dr. MacDonald and his team currently have a paper under review that confirms previous evidence of methane on K2-18 b, but finds no evidence of dimethyl sulfide or of carbon dioxide.
arxiv.org/abs/2501.18477

Dr. MacDonald says "any claim of life beyond Earth needs to be rigorously checked by other scientists, and unfortunately many previous exciting claims for K2-18b haven’t withstood these independent checks.” This can include new observations, new data processing, or models with different molecules.

Astronomers claim strongest evidence of alien life yet On a faraway planet, the James Webb Space Telescope has picked up signs of molecules that, on Earth, are produced only by living organisms – but researchers say we must interpret the results cautiousl...

These discussions have happened before. Former Carl Sagan Institute fellow Dr. Ryan MacDonald pointed out that previous detections of similar strength “have completely vanished when subject to closer scrutiny."

www.newscientist.com/article/2477...

This model with only dimethyl sulfide/disulfide may fit the data better than their previous models, but that does not mean it is the only model in existence that could fit the data well. The signals could still be caused by molecules not included in the model, or by complex chemical interactions.

Contributions of certain molecules to the blue model from the previous plot. Beyond a wavelength of 9 micrometers, dimethyl sulfide and dimethyl disulfide are the only molecules with large contributions to the overall model, since Madhusudhan et al. removed other molecules that could contribute. This is why dimethyl sulfide and dimethyl disulfide are "detected"—nothing else competes with them in this range.

However, they then create a different model for the possible “detection,” which removes all molecules that may show signals in the same range as dimethyl sulfide/disulfide.

The recent Madhusudhan et al. analysis begins by considering 20 molecules. They find that the model with dimethyl sulfide/disulfide fits the data around twice as well as the model where they are removed.

Plot of red JWST data against Madhusudhan et al.'s model in blue/yellow. As explained next in the thread, this model removes all other molecules that may show signals in the same range as dimethyl sulfide/disulfide, potentially biasing the result in favor of dimethyl sulfide/disulfide. The red JWST data also does not always align with the model; this could be a fluke during the collecting and processing of data, or an indication that the model needs more or different molecules to achieve a better fit.

For this reason, data points can have huge error bars—as seen by the red points in the new K2-18 b plot below—and sometimes fail to overlap certain models (in blue/yellow). So why the conclusion that dimethyl sulfide, and the related molecule dimethyl disulfide, might exist in this atmosphere?

K2-18 b - NASA Science K2-18 b is a super Earth exoplanet that orbits a M-type star. Its mass is 8.92 Earths, it takes 32.9 days to complete one orbit of its star, and is 0.1429 AU from its star. Its discovery was announced...

Most exoplanets are incredibly far from Earth, and our instruments are still in their infancy. K2-18 b is 124 lightyears away, and even at nine times the mass of Earth, it's small compared to most planets we’ve observed.

science.nasa.gov/exoplanet-ca...

Artist depiction of an exoplanet (Celestialobjects/Pablo Carlos Budassi) with the text "LIFE ON AN OCEAN WORLD? Do these 'hints of life' hold water?"

Has JWST found life on another world? 🔭

An analysis of exoplanet K2-18 b points to the existence of dimethyl sulfide, a molecule produced by photosynthesizing plankton on Earth—but proving that this sign is real, and that life is the only explanation, is a difficult task.

arxiv.org/abs/2504.12267

Stay tuned for the publication of the paper, and feel free to use and edit these images however you like (keeping the credit lines intact)!

Paper preprint: ui.adsabs.harvard.edu/abs/2025arXi...

Bohl et al.'s paper identifies the best targets for follow-up observing, in the hopes that we may soon narrow down the theory into reality—making the habitable zone a more robust filter in our search to find life beyond our Solar System.

Scientists have also proposed many different limits for the habitable zone. Pictured here are the broadest Kopparapu et al. limits and the narrower Ramirez & Kaltenegger limits. But who's to say which is right? It's all theoretical—we've gathered almost no atmospheric data yet for these planets.

From the image, Kepler-452 b looks closest to Earth in terms of energy it receives and type of star it orbits. However, many of the planets discovered by the Kepler spacecraft are hundreds of lightyears away, making them harder to study than much nearer red dwarf planets (lower third of this plot).