Precision, Imprecision, Intellectual Honesty, And Little Green Men

October 18, 2025 by Elliot Williams 33 Comments

If you’ve been following the hubbub about 3I/ATLAS, you’re probably either in the camp that thinks it’s just a comet from ridiculously far away that’s managed to find its way into our solar system, or you’re preparing for an alien invasion. (Lukewarm take: it’s just a fast moving comet.) But that doesn’t stop it from being interesting – its relatively fast speed and odd trajectory make astronomers wonder where it’s coming from, and give us clues about how old it is likely to be.

Astronomy is the odd-man-out in the natural sciences. In most branches of physics, chemistry, and even biology, you can run experiments. Even those non-experimental corners of the above fields, like botany, for instance, you can get your hands on the objects you’re talking about. Not so astronomy. When I was studying in college, one of my professors quipped that astronomers were pretty happy when they could hammer down a value within an order of magnitude, and ecstatic when they could get a factor of two or three. The deck is simply stacked against them.

With that background, I love two recent papers about 3I/ATLAS. The first tries to figure out why it’s moving so fast by figuring out if it’s been going that fast since its sun kicked it out, or if it has picked up a gravitational boost along the way. While they can’t go all the way back in time, they’ve worked out whether it has flown by anything close enough to get a significant boost over the last 10 million years. This is impressive that we can calculate the trajectory so far back, but at the same time, 10 million years is peanuts on the cosmic timescale.

According to another paper, there is a weak relationship between interstellar objects’ age and their velocity, with faster-moving rocks being older, they can estimate the age of 3I/ATLAS at between 7.6 and 14 billion years old, assuming no gravitational boosts along the way. While an age range of 7 billion years may seem like a lot, that’s only a factor of two. A winner for astronomy!

Snarkiness aside, its old age does make a testable prediction, namely that it should be relatively full of water ice. So as 3I/ATLAS comes closer to the sun in the next few weeks, we’ll either see it spitting off lots of water vapor, and the age prediction checks out, or we won’t, and they’ll need to figure out why.

Whatever happens, I appreciate how astronomers aren’t afraid to outline what they can’t know – orbital dynamics further back than a certain date, or the precise age of rocks based solely on their velocity. Most have also been cautious about calling the comet a spaceship. On the other hand, if it is, one thing’s for sure: after a longer-than-10-million-year road trip, whoever is on board that thing is going to be hungry.

Hackaday Links: August 17, 2025

August 17, 2025 by Dan Maloney 15 Comments

We’ve studiously avoided any mention of our latest interstellar visitor, 3I/Atlas, on these pages, mainly because of all the hoopla in the popular press about how Avi Loeb thinks it’s aliens, because of course he does. And we’re not saying it’s aliens either, mainly because we’d never be lucky enough to be alive during an actual alien invasion — life just hasn’t historically been that kind to us. So chances are overwhelming that 3I/Atlas is just a comet, but man, it’s doing its level best to look like it’s not, which means it’s time to brave the slings and arrows and wade into this subject.

The number of oddities surrounding 3I/Atlas just keeps growing, from its weird Sun-directed particle stream to its extreme speed, not to mention a trajectory through the solar system that puts it just a fraction of an astronomical unit from two of the three planets within the “Goldilocks Zone” of our star — ignore the fact that at an estimated seven billion years old, 3I/Atlas likely would have started its interstellar journey well before our solar system had even started forming. Still, it’s the trajectory that intrigues us, especially the fact that it’s coming in at a very shallow along to the ecliptic, and seems like it will cross that imaginary plane almost exactly when it makes its closest approach to the Sun on October 29, which just coincidentally happens to be at the very moment Earth is exactly on the opposite side of our star. We’ll be as far as possible from the action on that date, with the comet conveniently lost in the glare of the Sun. Yes, there’s talk of re-tasking some of our spacecraft around Mars or in the Jovian system to take a peek when 3I/Atlas passes through their neighborhoods, but those are complicated affairs that show no sign of bearing fruit in the short time left before the comet heads back out into the Deep Dark. Too bad; we’d really love an up-close and personal look at this thing.

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The Solar System Is Weirder Than You Think

June 17, 2024 by Elliot Williams 50 Comments

When I was a kid, the solar system was simple. There were nine planets and they all orbited in more-or-less circles around the sun. This same sun-and-a-handful-of-planets scheme repeated itself again and again throughout our galaxy, and these galaxies make up the universe. It’s a great story that’s easy to wrap your mind around, and of course it’s a great first approximation, except maybe that “nine planets” thing, which was just a fluke that we’ll examine shortly.

What’s happened since, however, is that telescopes have gotten significantly better, and many more bodies of all sorts have been discovered in the solar system which is awesome. But as a casual astronomy observer, I’ve given up hope of holding on to a simple mental model. The solar system is just too weird.

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Hackaday Links: April 24, 2022

April 24, 2022 by Dan Maloney 11 Comments

Wait, what? Is it possible that a tech company just killed off a product with a huge installed base of hardware and a community of dedicated users, and it wasn’t Google? Apparently not, if the stories of the sudden demise of Insteon are to be believed. The cloud-based home automation concern seems to have just disappeared — users report the service went offline at the end of last week, and hasn’t been back since. What’s more, the company’s executives removed Insteon from their LinkedIn profiles, and the CEO himself went so far as to remove his entire page from LinkedIn. The reasons behind the sudden disappearance remained a mystery until today, when The Register reported that Smartlabs, Inc., the parent company of Insteon, had become financially insolvent after an expected sale of the company failed in March. The fact that the company apparently knew this was going to happen weeks ago and never bothered to give the community a heads up before pulling the switches has led to a lot of hard feelings among the estimated 100,000 Insteonhub users.

Then again, with a comet the size of Rhode Island heading our way, a bunch of bricked smart bulbs might just be a moot point. The comet, known as C/2014 UN271, has a nucleus that is far larger than any previously discovered comet, which makes it a bit of an oddball and an exciting object to study. For those not familiar with the United States, Rhode Island is said to be a state wedged between Connecticut and Massachusetts, but even having lived in both those states, we couldn’t vouch for that. For scale, it’s about 80 miles (128 km) across, or a little bit bigger than Luxembourg, which we’re pretty sure is mythical, too. The comet is a couple of billion miles away at this point; it may never get closer than a billion miles from the Sun, and that in 2031. But given the way things have been going these last few years, we’re not banking on anything.

From the “Answering the Important Questions” file, news this week of the Massachusetts Institute of Technology’s breakthrough development of the “Oreometer,” a device to characterize the physical properties of Oreo cookies. The 3D printed device is capable of clamping onto the wafer parts of the popular sandwich cookie while applying axial torque. The yield strength of the tasty goop gluing the two wafers together can be analyzed, with particular emphasis on elucidating why it always seems to stay primarily on one wafer. Thoughtfully, the MIT folks made the Oreometer models available to one and all, so you can print one up and start your own line of cookie-related research. As a starting point, maybe take a look at the shear strength of the different flavors of Oreo, which might answer why the world needs Carrot Cake Oreos.

And finally, since we mentioned the word “skiving” last week in this space, it seems like the all-knowing algorithm has taken it upon itself to throw this fascinating look at bookbinding into our feed. We’re not complaining, mind you; the look inside Dublin’s J.E. Newman and Sons bookbinding shop, circa 1981, was worth every second of the 23-minute video. Absolutely everything was done by hand back then, and we’d imagine that very little has changed in the shop over the ensuing decades. The detail work is incredible, especially considering that very few jigs or fixtures are used to ensure that everything lines up. By the way, “skiving” in this case refers to the process of thinning out leather using a razor-sharp knife held on a bias to the material. It’s similar to the just-as-fascinating process used to make heat sinks that we happened upon last week.

Don’t Wait, You Need To See Comet NEOWISE Right Now

July 14, 2020 by Tom Nardi 74 Comments

By now you’ve heard of NEOWISE, the most spectacular comet to visit our little corner of the galaxy since Hale-Bopp passed through over 20 years ago. But we’re willing to bet you haven’t actually seen it with your own eyes. That’s because up until now, the only way to view this interstellar traveler was to wake up in the pre-dawn hours; an especially difficult requirement considering a large chunk of the population has gotten used to sleeping-in over the last few months.

But things are about to change as NEOWISE begins a new phase of its trip through our celestial neck of the woods. Having come to within 44.5 million km (27.7 million miles) of the sun on July 3rd, the comet is now making its way back out of our solar system. Thanks to the complex dance of the heavens, that means that observers in the Northern Hemisphere will now be able to see NEOWISE in the evening sky just above the horizon.

NEOWISE is on a kind of “up and over” trajectory compared to the orbital paths of the planets. Get a better feel for it with JPL’s interactive solar dynamics tool.

While NEOWISE might be beating a hasty retreat from Sol right now, the comet it actually getting closer to us in the process. On July 22nd it will reach perigee, that is, the point in its orbit closest to Earth. On that evening the comet will be approximately 103 million km (64 million miles) away. Not exactly a stone’s throw, but pretty close in astronomical terms. The comet will appear to be getting higher in the sky as it approaches Earth, and should be visible with the naked eye between 10 and 20 degrees above the northern horizon.

Most estimates say that NEOWISE should remain visible until at least the middle of August, though it will be dimming rapidly. After that, you’re going to have to wait awhile for a repeat showing. Given the orbit of this particular comet, it won’t come around our way again for approximately 6,800 years, give or take a few lifetimes.

NASA will be hosting a NEOWISE live stream tomorrow afternoon where researchers will answer questions about this once in a lifetime celestial event, though we think you’ll get a lot more out of it if you just go outside and look up.

Maria Mitchell: The First Woman Astronomy Professor

December 12, 2017 by Dan Maloney 11 Comments

On an October night in 1847, a telescope on the roof of the Pacific National Bank building on Nantucket Island was trained onto the deep black sky. At the eyepiece was an accomplished amateur astronomer on the verge of a major discovery — a new comet, one not recorded in any almanac. The comet, which we today know by the dry designator C/1847 T1, is more popularly known as “Miss Mitchell’s Comet,” named after its discoverer, a 29-year old woman named Maria Mitchell. The discovery of the comet would, after a fashion, secure her reputation as a scholar and a scientist, but it was hardly her first success, and it wouldn’t be her last by a long shot.

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How To Hack A Spacecraft To Die Gracefully

October 3, 2016 by Richard Baguley 64 Comments

Last week, the Rosetta spacecraft crashed into comet 67P/Churyumov-Gerasimenko after orbiting it since 2014. It was supposed to do that: the mission was at an end, and the mission designers wanted to end it by getting a close look at the surface of the comet. But this raises an interesting problem: how do you get a device that is designed to never stop to actually stop?
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