Joseph R. Farah: nasa

Showing posts with label nasa. Show all posts

Tuesday, September 8, 2026

Google's AI overview got cosmic rays all wrong

See also this Astraveo video:

A few days ago, I uploaded a video explaining that the Mars jellyfish anomaly was very likely to be a cosmic ray artifact due to the presence of a row of clipped pixels with no antialiasing, a sure sign of an imaging artifact--real objects, even alien spacecraft, don't produce that. I explained the mechanism for how a cosmic ray can create an artifact on an image sensor, and explicitly showed how if it impacts during a calibration frame, the subtraction can produce a black artifact on the final image. I then provided an independent confirmation of this in the form of the Mars Science Laboratory camera engineering lead explicitly describing this exact process producing a black artifact in an image from a few years ago.

Despite this, I saw a surprising number of comments that confidently and incorrectly insisted that cosmic rays can only produce white artifacts, never black. Here's a few:

"As I understand it, and if the supposed experts are really experts who know what they are talking about, cosmic rays are never black."
"You may be an astrophysicist but you definitely aren't a photographer. Cosmic ray hitting a camera sensor would not leave a black spot of multiple pixels. It would excite the sensor leaving a bright white spot and it would be permanent."
"I have never seen a black cosmic ray artifact. It is always white."

I responded to each of these and more, reiterating the dark frame explanation from the video. But it did get me wondering--why are there so many people repeating this incorrect thing so confidently? I scratched my head about it for a while, but I didn't get a clue until a friend texted me something alarming--he had Googled a question about cosmic rays and Google gave him an answer that conflicted with my own!

I was frankly shocked by this. Cosmic rays creating black artifacts due to subtraction of calibration images is a very well-known and understood effect. It was not only confirmed by the MSL lead camera engineer but its even reproduced by amateur astronomers, like this thread on Cloudy Nights where AlphaTriplePlus says:

If you use a master dark for calibration that has a cosmic ray hit, the calibrated lights will probably exhibit a wiggly black streak as the hot pixel streak in the master dark is subtracted from every light in the live stack. Happened to me last night!

So why did Google's AI overview get it wrong? I decided to investigate a little. I tried my friend's query and was able to reproduce what he saw. Asking "do cosmic rays cause dark artifacts?" caused Google's AI overview to confidently say, "No, cosmic rays do not cause dark artifacts", even bolding and highlighting the wrong answer! I even tried asking a few different ways--asking specifically whether cosmic rays can cause dark artifacts when impacting on a bias frame (wrong answer still!) or even going as specific as asking "if a cosmic rays strikes during calibration image acquisition, can the final image have a black artifact?" (wrong answer again!)

But after a few prompts, I did notice something interesting. Even though it always highlights and bolds the wrong answer, sometimes, buried down deep in the answer, is the right answer, which it for some reason didn't feel was important enough to point out. For example, in the very first prompt--"can cosmic rays cause dark artifacts"--while it highlights and bolds its "no" answer, it has a section below titled "What causes dark artifacts?" where it explicitly says that "subtracting a master dark frame can create dark "holes" or negative spots if a hot pixel was not active during the actual exposure." That's literally the explanation I gave in the original video, where the hot pixel is caused by a cosmic ray, and the correct answer to the question! But its buried down in the answer for some reason.

However, seeing this right answer pop up in the response, just buried, gave me an idea about how to get it to give the right answer. If you ask it specifically, "what artifact does a cosmic ray in a dark frame create after dark subtraction?" it will give the right answer--a negative pixel or a black hole/spot in the resulting calibrated image. So if you used AI to validate your comment by just googling and reading the first line in the Google AI overview, I hope this clears that up--its just a logical error from Google's AI overview. And I hope this makes it clear that AI makes mistakes very frequently and it is always better to try and dig up the answer yourself, or talk to an expert vs blindly accepting an AI's answer at face value, especially if the question is in a field that isn't your own. You have to be careful about interpreting responses from any AI, as exemplified by this problem we and you may have encountered trying to use AI to understand a subject as complex as image analysis of an optical camera in a very harsh planetary environment.

For the record, I tested this problem on ChatGPT and Claude as well, on the weakest models to give AI overview a fair shake. ChatGPT made a similar error but put the right answer right near the top, so I would consider that a success. If you don't read one sentence down that's kind of your fault. Claude just got the right answer out of the box. This seems to be an issue with Gemini relying too much on the fact that "cosmic rays" are most often associated with "bright artifact", but its a perfect example of how LLMs which may assume the correct answer is the one most repeated in the training data can be deeply flawed if not paired with careful reasoning capabilities and primary sources.

This also leads into something else I want to discuss, which was another theme in the comments. If AI can't be trusted--and to be clear, the answer is, it cannot--what can you trust? More importantly, I realize that I'm essentially pitting myself against Google here, which has vastly more knowledge than I have. Why should you trust me over Google Gemini, a powerful frontier AI model?

I saw this question raised many times in the comments. One common theme was the idea that astrophysicists don't know anything about imaging, or insinuating that astrophysics and imaging/sensing/photography are somehow disjoint mutually exclusive fields. If you think this, I can of course understand why you might be hesitant to trust my explanation when Google is very vehemently telling you the opposite. So I wanted to dive into this a bit.

First, you don't need to trust me or Google at all. All the analysis in the previous video is analysis you can do yourselves. You can check the pixel values and see they are either (0, 0, 0) or (1, 1, 1) in the region of the artifact--that's classic clipping. You can see it goes from pitch black to sky-white with zero antialiasing, a sure sign of a sensor glitch. And if you think that I, as an astrophysicist, am not qualified to weigh in here, I showed an email from the lead engineer on the MSL camera explaining away a similar black artifact as a "textbook cosmic ray". And I assure you, the lead engineer for the MSL camera is indeed an expert on imaging.

But I would also like to speak up in defense a bit of astrophysicists everywhere. Reading comments like this, I feel like there is a severe misconception about what astrophysicists do and where our expertise lies. The vast majority of astrophysicists are observational or experimental astrophysicists, and while many of us including myself spend a lot of time working with theory and with theorists, most of our work is on data captured via imaging. How do you think we study the stars? :) We can't exactly go to them. We mostly just take pictures--sometimes fancy pictures, like what a spectrograph does, or pictures in non-optical wavelengths, like what radio telescopes do--but they are just pictures, and we analyze them and extract data from them. Even if you don't specialize in imaging, you almost certainly know fundamental principles of imaging and the details of the instrument you work on specifically, and these fundamental principles and many instrument details are shared across almost all imaging instruments. Many of us work at observatories directly and have our hands on the raw data flowing in from the telescopes. Some of us, in this case not me, but like my Astraveo colleague and good friend Dr. David James, have built the telescopes and cameras on these mountaintops with our bare hands. While I mostly work with observational data and how we can use that data to test our various theories, David literally built an enormous telescope on top of Mauna Kea in 2010!

I am also happy to point to my own credentials here, which I think serves as a good example of how even an astrophysicist who does not work directly on the instrument hardware must learn the details and nuances of imaging in order to do any level of data processing. In my PhD thesis alone there are countless examples of this--almost every paper I ever wrote features some discussion of handling image artifacts, and almost every paper I wrote features discussion of image artifacts specific to cosmic rays! Here are a few instances.

In any paper I wrote on imaging supernovae, we had to analyze the data with pipelines that explicitly include cosmic ray flagging and rejection. This includes recent papers from 2025 and 2026, which explicitly discuss this pipeline, and even have specific discussions of a feature in one of our spectra caused by a large, narrow cosmic-ray artifact, which is something we had to work around. In another paper, we use similar cosmic ray detection and flagging in photometry collected from many different instruments across UV optical and near-infrared wavelengths.

In one paper, we found a very early data point from ATLAS, and we weren't sure whether it was imaging noise or actually data from the supernova. It matched our model but that could have been a coincidence, and the statistical significance was only 2sigma. Using extensive analysis of the science imaging as well as control curves and the processing pipeline, we were able to moderately increase the significance to almost 3sigma but ultimately left the result inconclusive. This is a good example of the high standards we have for considering whether something is data or noise--even though we found that there was less than 1% chance that the data point was purely noise, we still determined it to be inconclusive, because with millions of data points, a less than 1 in a 100 chance isn't as unlikely as it sounds. So when you see us being cautious about artifacts or looking carefully at data, we're not just kowtowing to the "establishment", "accepting NASA's explanation", or "bending to peer pressure". We're trying to be rigorous and hold things to a high standard of discovery, because that's the only way actual science gets done.

My point with this is to say that even I, an astrophysicist who doesn't work directly on instrumentation, has had to become deeply involved and experienced with imaging algorithms and artifacts just to get my work done. So the separation that's being drawn between astrophysicists and imaging is not a very good one because that line is very blurry. So if you're wondering who to trust and your choices are between astrophysicists or AI--particularly the Google AI overview--I hope this gives a bit more info for you to make your decision.

Previously on this blog:

Did NASA find a jellyfish on Mars?

Debunk

This is an older image that has been making the rounds lately, thanks to a few posts on reddit and some new amplification from tabloids like The Daily Mail, which published the responsible and level-headed headline, "Mysterious 'jellyfish' spotted in NASA Mars photo sparks theories of life on the Red Planet". Reading through the comments from UFO and alien life enthusiasts, I spotted a lot of interesting methodological problems in the way the discussions were being handled that I think are actually quite instructive. So can we figure out what this thing is, and if we can't, does that mean it is aliens?

Let's look at the evidence. First, it's objectively there. There's clearly something in the actual image from NASA that needs to be explained. This isn't an editing artifact or something someone photoshopped. Something in real life happened, and the camera recorded it. And it was something that wasn't there before, in the previous image. That's a big part I think of why this is gaining so much steam and attention.

Second, the location does seem rather odd. I saw a lot of comments saying things like, "what are the odds that a glitch or something similar would be perfectly hovering above the landscape, with its tendrils reaching down like a tripod?" And that does seem a little unusual. But without characterizing what this could be, its hard to say whether its really that unusual. And I'll to that in a minute, because I think this is an extremely common but very poorly understood source of bias in how human beings interpret low-sample data.

Finally, the shape. I'll admit, it really does look like something straight out of War of the Worlds. But this is a pretty well understood human perception thing. We like to see patterns and shapes and so we do--everywhere. Even in the random things, like the stars in the night sky, or the random inkblots of the Rorschach test.

But while the 3 things I mentioned have been shared as "evidence", they aren't really. I don't mean they don't mean aliens, I hope that's obvious at this point in the video, I mean they aren't telling you anything. The people who are commenting that its not there in the previous image and therefore it must be moving are neglecting the fact that the previous image was taken just 13 seconds earlier, which feels like if it is a big creature in the distance moving, that would be kind of fast. Especially since the "jellyfish" or "moving body" explanation would suggest its moving from right to left, pretty far away--that's a lot of ground to cover in 13 seconds, with no motion blur.

And as for the shape, a lot of what we are perceiving as the "shape" is due to intentional or accidental blurring or processing of the image as we zoom in on it or as people try to enhance it with various programs. But you can look at it pixel by pixel, using several freely available online tools. If we do this, we find that it does look weird, but it certainly doesn't look like a jellyfish or a tripod. There is an almost perfectly black line of pixels--and when I say perfectly black I mean the pixel values are (0, 0, 0) for some of these--with a fuzzy single streak looking thing below it. I don't see the "tripod" at all in this view. In fact, the two other "legs" of what I assume are the "tripod" that people are talking about are just consistent with the sky noise. Also, looking closer, unlike every other object in the image, which has some level of antialiasing (which is when the edges of real-life objects don't get perfectly terminated on a pixel, they kind of get blurred a little) the anomaly is a single row of a couple pixels perfectly terminating at the pixel boundary, without any sign of the antialiasing-like effect that a real object would have. So while there's definitely some signal here, we have been grossly misleading ourselves about the shape and structure, and even whether this is a real object in the camera.

But now we have the actual shape and structure, as we can we see here. What could cause a perfectly black row of pixels with a fuzzy streak below it? and can it explain some of the other weirdness, like the suspicious location, or the fact that its not there just a few moments earlier?

Explanation

In my opinion as an astrophysicist, this is not a real object at all. I think this is just a camera glitch. And a very specific kind of camera glitch caused by something called a "cosmic ray".

See, space is filled with very high energy, fast moving particles. And sometimes--a lot of the time actually--those particles hit things. When a cosmic ray hits Earth's atmosphere, it creates a shower of secondary particles that can be detected even at the Earth's surface. We don't exactly know where they come from, but we see a LOT of them, and they seem to be coming from deep space and from the Sun.

So, how can cosmic rays create camera glitches? Well it comes down to how cameras work. Here is an overly simplified explanation. The sensor of a camera is something called a charge-coupled device, or CCD. When a photon enters a camera sensor and strikes a pixel, that photon interacts with a little piece of silicon that generates an electron. That electron is then captured by a capacitor during the exposure. The more photons interact with the little piece of silicon, the more electrons are generated and captured. When the exposure is done, the camera computer "reads out" the number of electrons counted at each pixel, and the number of electrons there are tells you the number of photons. So, more electrons, means a brighter pixel. Doing this for every pixel in the sensor across the red, green and blue pixels, gives you a whole image.

The problem is, photons aren't the only thing that can generate electrons. If a cosmic ray--which we don't care about in a picture--strikes the camera at the right angle, it can create a huge number of electrons across several pixels in the image. This is almost always far more electrons than the scene would normally generate, and so when the camera reads out the image, you'll get a big white streak that can come in many different shapes and sizes and configurations, basically anywhere in the image.

So basically what I think happened is a cosmic ray struck the camera at the exact right moment and left this big ol artifact in the image. It explains why the shape is so weird--just a perfect row of pixels with no antialiasing-- and why it wasn't present just 13 seconds earlier--a cosmic ray strike is a tiny fraction of a second event--and it also explains a few other weird things. For example, you might be wondering why is the cosmic ray artifact black here, when all the other images I've showed you so far have been white streaks. Well, NASA cameras are pretty brilliant things. As part of the process of taking an image, they take something called a "dark bias frame", which is an image taken with the camera shutter closed, to create a calibration frame that is then subtracted from the actual image. The idea here is the temperature of the environment and the camera itself can create a low-level background of photons that we don't want in our images. So by taking a picture with the shutter closed, we can measure the background that will be present in our image with the shutter open, and subtract it away to make the image more accurate.

But, if a cosmic ray strikes the camera while the bias frame is being taken, it will create a HUGE white artifact. When that artifact is then subtracted from the real image, it will leave a pitch black remnant.

The cosmic ray explanation can also explain the strange location--in that, there's nothing to explain at all. Cosmic ray hits are very frequent. They happen all the time in every instrument. They are especially frequent on Mars, which has a thin atmosphere and weaker magnetic field than Earth's, making it worse at impinging the propagation of these rays. They happen all the time, at random spots in the images, meaning that eventually, you'll get one that seems to be in a suspicious spot, purely by chance, especially if its over the sky, where a black artifact will show up more clearly. But if you look at the anomaly as an individual event and try to say "oh, what are the odds that this happened right at this perfect spot", you can fool yourself into thinking that the event is rarer than it is. Another way to think about it is like seeing a strangely shaped cloud that looks exactly like something crazy. Intuitively, we know that while it feels rare, but we also know that any given SECOND there are billions and billions of clouds each with a different shape and so suddenly a particular shape being unusual doesn't seem that unlikely.

And this something that astrophysicists have to deal with too. In a recent paper we published, we found a really strange signal--the first of its kind. We did our best to characterize it and convince ourselves that the signal was real, which wasn't so hard because the data were really high quality and the signal was very strong and occurred over a long time--over 100 days. But even though it was a very exciting find, the consensus of the community--including us, the authors--was that the only way to know for sure that this isn't a fluke is to find more of them. And even our followup work now is trying to find different ways to assess whether the signal could be real or just some type of noise. So this is something that happens all the time, and once you see how much random stuff the universe is capable of throwing at you that looks exactly like something incredible but turns out to be something kind of mundane, you sort of learn that it is much easier to trick yourself that you've proved something than it is to actually prove something beyond a shadow of a doubt. As a famous physicist once said, "The first principle is that you must not fool yourself--and that you are the easiest person to fool."

This idea of finding more similar events to show that your explanation is not a fluke leads perfectly into the final piece of this puzzle, which is that we've seen stuff like this a TON on Mars and elsewhere. Here are just a few examples that NASA themselves have published of cosmic ray streaks appearing in their cameras. Here are some that look quite similar to the strange jellyfish one we've been discussing today, complete with pitch black cores and strange dangling appendages and streaks. And to really nail it home, here is an email from Justin Maki, the engineering lead for the MSL camera, responding to a question from an enthusiast about a very similar artifact identified just a year earlier, confirming that these strange streaks are indeed cosmic rays striking the sensor during the acquisition of a dark bias frame. So that's where my money for this one, too.

Previously on this blog:

Tuesday, February 27, 2024

Thermal vacuum testing for the Europa Clipper

NASA (via YouTube):

We'll be back soon. The spacecraft is currently undergoing vacuum testing.

I was a huge fan of the livestream for building the Perseverance rover--I'm glad they've got another one running for Clipper. It's fun to check in on the progress of the build and try to guess what they're working on at any given moment.

Astrobiology.com:

Scheduled to launch in October 2024 and arrive in the Jupiter system in 2030, NASA’s Europa Clipper mission will place a spacecraft in orbit around Jupiter to perform a detailed investigation of Europa.
This will maximize the scientific return from the lifetime of Europa Clipper, which is investigating the “habitability” of Europa. Habitability is a measure of whether Europa could support life and includes the presence of essential ingredients like liquid water, chemical building blocks and an energy source.
“Europa is considered one of the most likely sites in our solar system to potentially find life,” said SwRI Lead Scientist Dr. Kelly Miller.

Phys.org:

Today is a big day for the Europa Clipper team. They'll be testing the craft's thermal pumping system, the last major addition to the spacecraft's vault, a thick-walled aluminum alloy box that holds the spacecraft's "brain": its electronics and computers.
"The thermal pump is the heart of the spacecraft," pumping fluid through tubing to control the craft's temperature, Barajas said. The daylong effort is hazardous because of the high pressure used to test the system with helium, a nonflammable gas.
"Planetary protection has evolved," Barajas said of the strict work requirements he has to follow every day. "No one wants to be the person responsible when extra-terrestrial life is finally found and it turns out to be something we brought there from earth."
"I think that's where the stress comes from, right? That we feel the pressure and the burden of building this vehicle that has been the life's work of some and years of work for many others."

I'll continue updating this thread with news of the Europa Clipper development.

Thursday, January 4, 2024

Coronal mass ejection from colossal New Year's Eve solar flare will strike Earth today

Space.com:

The coronal mass ejection CME was hurled into space by an X-class solar flare that burst from the surface of the sun at 4:55 p.m. EST (2155 GMT) on Sunday (Dec. 31). It is the most powerful flare that has happened on the sun during the current solar cycle, solar cycle 25, which began in Dec. 2019. In fact, the flare that ended 2023 with a bang is the largest that has been observed since Sept. 10, 2017, according to the Space Weather Prediction Center of the National Oceanic And Atmospheric Administration (NOAA).

I'm always amused by these comparisons articles like to make. "Largest that has been observed since 2017". We're approaching solar maximum so the flares will be the largest in the cycle. The solar cycle is ~11 years so the last maximum was in the early 2010s, and the last minimum was in the late 2010s. "This solar flare at near maximum was bigger than the ones at the minimum" has substantially less punch.

Storms like this have the capability to cause weak fluctuations in power grids and could have minor impacts on satellite operations. In addition to this, G1 geomagnetic storms can give rise to striking auroras, beautiful light shows seen over Earth, usually at higher latitudes.
In 2003, during the last solar maximum — the peak of the sun's activity during the solar cycle 24 — an X45 flare was seen erupting from the sun, the most powerful solar flare ever measured.
A powerful X-class flare like the one seen on New Year's Eve has the potential for long-lasting radiation storms, which can damage satellites, including GPS, and affect aircraft flying near the poles of Earth, even giving passengers on these flights small radiation doses. X flares also have the potential to cause worldwide blackouts, if conditions were just right.

The Hill:

In an update Sunday evening, NOAA’s Space Weather Prediction Center (SWPC) released an image of the flare, which appeared as a large, glowing spot on the sun. You can see that image below.

Image reproduced from thehill.com. Original caption: An X5 solar flare detected by NOAA’s Space Weather Prediction Center on December 31, 2023. (NOAA SWPC; cropped)

At an X5, Sunday’s flare was much smaller than the flare recorded in 2003. It was, however, the strongest since September 2017, when an X8.2 flare was detected, according to the SWPC. This flare also supersedes an X2.8 solar flare reported in the same region of the sun on December 14. At the time, the SWPC reported that flare was “likely one of the largest solar radio events ever recorded.”

Possible effects:

The SWPC said those using high-frequency radio signals (like emergency managers) may notice a “temporary degradation or complete loss of signal on much of the sunlit side of Earth” as a result of Sunday’s solar flare.

Previously on this blog:

Tuesday, December 5, 2023

Saturn's icy moon may hold the building blocks of life

Phys.org:

Evidence indicates that Saturn's icy moon Enceladus is an 'ocean world' that contains all three, making it a prime target in the search for life.
During its 20-year mission, NASA's Cassini spacecraft discovered that ice plumes spew from Enceladus' surface at approximately 800 miles per hour (400 m/s). These plumes provide an excellent opportunity to collect samples and study the composition of Enceladus' oceans and their potential habitability.
Now, researchers from the University of California San Diego have shown unambiguous laboratory evidence that amino acids transported in these ice plumes can survive impact speeds of up to 4.2 km/s, supporting their detection during sampling by spacecraft.

PNAS:

The icy moons of Saturn and Jupiter, Enceladus and Europa, are particularly promising for hosting life, as they have shown evidence for the three important criteria: water, energy, and organic chemicals. Both moons eject their subsurface ocean material as a plume of icy particles, providing the opportunity to study the ocean composition and potential habitability via plume flythrough sampling.
We show that amino acids entrained in ice grains can be detected intact after impact at speeds up to 4.2 km/s and that salt reduces their detectability, validating the predictions from other model systems. Our results provide a benchmark for this orbital sampling method to successfully detect signs of life and for the interpretation of past and future data.

I've always been personally excited by the original Enceladus discovery made by Cassini. It was already such a bizarre little moon to begin with, with the smooth southern geography, but the discovery of these liquid water plumes indicating a warm ocean under the surface was absolutely wonderful. There tends to be excitement and interest in finding aliens far outside of Earth, but if we honest-to-goodness to find alien life or at least the building blocks for it, it'll likely be in the plumes of Enceladus, quite close to home.

Tuesday, April 4, 2023

Global Geomagnetic Perturbation Forecasting Using Deep Learning

AGU:

Geomagnetically Induced Currents (GICs) arise from spatio-temporal changes to Earth's magnetic field, which arise from the interaction of the solar wind with Earth's magnetosphere, and drive catastrophic destruction to our technologically dependent society. Hence, computational models to forecast GICs globally with large forecast horizon, high spatial resolution and temporal cadence are of increasing importance to perform prompt necessary mitigation.

Our model outperforms, or has consistent performance with state-of-the-practice high time cadence local and low time cadence global models, while also outperforming/having comparable performance with the benchmark models. Such quick inferences at high temporal cadence and arbitrary spatial resolutions may ultimately enable accurate forewarning of dB/dt for any place on Earth, resulting in precautionary measures to be taken in an informed manner.

Phys.org:

Like a tornado siren for life-threatening storms in America's heartland, a new computer model that combines artificial intelligence (AI) and NASA satellite data could sound the alarm for dangerous space weather.

The model uses AI to analyze spacecraft measurements of the solar wind (an unrelenting stream of material from the sun) and predict where an impending solar storm will strike, anywhere on Earth, with 30 minutes of advance warning. This could provide just enough time to prepare for these storms and prevent severe impacts on power grids and other critical infrastructure.

To help prepare, an international team of researchers at the Frontier Development Lab—a public-private partnership that includes NASA, the U.S. Geological Survey, and the U.S. Department of Energy—have been using artificial intelligence (AI) to look for connections between the solar wind and geomagnetic disruptions, or perturbations, that cause havoc on our technology. The researchers applied an AI method called "deep learning," which trains computers to recognize patterns based on previous examples. They used this type of AI to identify relationships between solar wind measurements from heliophysics missions (including ACE, Wind, IMP-8, and Geotail) and geomagnetic perturbations observed at ground stations across the planet.

Previously on this blog:

Tuesday, March 7, 2023

LCO Data Confirm the Success of NASA’s DART Mission

Las Cumbres Observatory:

The NASA Double Asteroid Redirection Test mission — the first test mission for NASA’s Planetary Defense Coordination Office — launched a spacecraft in November of 2021 with the aim to crash into the binary near-Earth asteroid system Didymos.

LCO scientists Dr. Tim Lister, Dr. Joey Chatelain, and Dr. Edward Gomez are coauthors on this paper. Dr. Lister heads the LCO group studying Near-Earth Objects, which employed data taken from LCO 1-m telescopes in South Africa and Chile for analysis. The data from the LCO telescopes, along with two others in Chile and planetary radar observations from Goldstone, CA, were used to measure the new period of Dimorphos after the DART impact.

Dr. Tim Lister is pleased that LCO played a vital role in the DART mission, “It’s been a great privilege to be involved with and contribute to such an important mission for planetary defense. Having LCO telescopes in both Chile and South Africa allowed us to compare with other telescopes in Chile and also capture parts of Dimorphos’s orbit that other telescopes couldn’t. LCO’s extensive telescope network in the Southern Hemisphere was important in being able to measure the period change so soon after the impact.”

DART is a really exciting project--it's really fun to watch these results unfold from a front row seat. Tim, Edward and Joey are awesome scientists, and Tim's talks about DART are phenomenal. I had the privilege and misfortune of speaking following a DART talk he gave at our local Astronomy on Tap; very tough act to follow.

Sunday, March 5, 2023

James Webb captures an extremely distant triple-lensed supernova

ESA/Webb:

This observation from the NASA/ESA/CSA James Webb Space Telescope contains three different images of the same supernova-hosting galaxy, all of which were created by a colossal gravitational lens. In this case, the lens is the galaxy cluster RX J2129, located around 3.2 billion light-years from Earth in the constellation Aquarius.

Astronomers discovered the supernova in the triply-lensed background galaxy using observations from the NASA/ESA Hubble Space Telescope, and they suspected that they had found a very distant Type Ia supernova.

SNe Type Ia function as standard candles, so if it really is Type Ia it could be used to determine a cosmic distance to RX J2129. However, I'm curious as to how they made this determination, as I didn't see any conclusive lightcurve or spectra associated with this find. No one has classified the supernova on TNS either. Update: apparently spectroscopy was obtained by NIRSpec but it's not clear if classification was possible.

Digital Trends:

The image features a huge galaxy cluster called RX J2129, located 3.2 billion light-years away, which is acting as a magnifying glass and bending light coming from more distant galaxies behind it. That’s what is causing the stretched-out shape of some of the galaxies toward the top right of the image.

CNET:

Not only does the galaxy appear three times, but it appears at different points in time. A supernova -- a bright exploding star -- is visible in the earliest version of the galaxy. The second and third images, from about 320 days and 1,000 days later, show that the supernova has faded away. An annotated version of the image points out these cool features:

Mashable:

Astronomers are now adept at spotting the telltale effects of gravitational lensing, but that wasn't always the case. Four decades ago, the concentric arcs of light and stretched celestial objects could be downright confusing. In 1987, an enormous blue arc thought to be hundreds of trillions of miles long was first considered one of the largest objects ever detected in space. The arc was found near the galaxy cluster Abell 370, with another similar object near galaxy cluster 2242-02.

Sunday, February 19, 2023

SWPC Reports X-Class Solar Flare

Solar Weather Prediction Center:

An X2.2/2b flare (R3) occurred late on February 17. The flare peaked Feb 17 15:16 ET. Effects: temporary degradation or complete loss of high-frequency radio signals on some of the sunlit side of the Earth.

NASA:

Solar flares are powerful bursts of energy. Flares and solar eruptions can impact radio communications, electric power grids, navigation signals, and pose risks to spacecraft and astronauts. This flare is classified as an X2.2 flare. X-class denotes the most intense flares, while the number provides more information about its strength.

FoxWeather:

According to the SWPC, the geomagnetic storm may affect satellite operations and could even lead to weak power-grid fluctuations. In addition, migratory animals could be affected, and the Northern Lights may be visible farther south than usual, like in northern Michigan and Maine.

A G2-level solar storm could affect high-latitude power systems by triggering voltage alarms, and long-duration storms could cause damage to transformers. In addition, corrective actions may be necessary for spacecraft orbiting Earth.

HaloCME (via Twitter):

I love this! Highly eruptive X2.2 flare with a nice coronal wave, although I doubt the CME will even glance Earth.

HaloCME has a fantastic visualization in that tweet.