Did Jupiter kill the dinosaurs?
💥 The planet we trusted to guard Earth may be flinging deadly rocks our way instead.
with Ethan Siegel • July 12, 2025
Greetings readers,
There's always so much going on in the world of science, even as those of us who are scientists struggle to make sense of everything we encounter. However, sometimes those moments where we say to ourselves, "Huh, that's funny," turn out to be incredible harbingers of a true, revolutionary advance. This week, in fact, there were three such moments that I got to write about.
First, while examining JWST data of the Ring Nebula, the closest known planetary nebula to Earth, scientists not only spotted enormous quantities of dust inside but also found that the dust was making a disk, one ripe with the same type of ingredients used to make planets around newly forming stars. Could planetary nebulae make planets, too? Next, while scanning the skies repeatedly, the ATLAS array of telescopes found something startling: a new interstellar interloper, the third one ever, that turns out to be larger and faster-moving than any we've spotted yet, and by enormous amounts! And then, despite a longstanding prediction that the top quark should be a loner, decaying before forming a bound state, physicists at both CMS and ATLAS (a different ATLAS, the particle detector, not the telescope array) found "gold standard" evidence for toponium: a bound state of top-antitop pairs.
In addition to those, we also have stories about how Jupiter isn't our great cosmic shield, but rather a great foe, leading to far greater numbers of planetary collisions than Earth would have experienced without it. The worst prediction in the history of physics is just as unresolved as ever, as we can't explain the value of the cosmological constant we observe. And there's a brand new podcast out for July: on the cosmic microwave background, in more detail than you've likely ever heard before. It's an incredible time to be alive for human knowledge, so stick with me and we'll explore as far as we can!
All the best,
Ethan
COLLISION COURSE
Jupiter endangers Earth and may have extincted the dinosaurs
Sixty-five million years ago, a massive asteroid struck Earth. Jupiter not only didn’t stop it, but it most likely caused the impact. Many have wondered why Jupiter, which allegedly protects the inner planets from catastrophic impacts, was unable to shield Earth from this one. Let’s explore what happened.
QUARKY DISCOVERY
The top quark isn’t a loner after all: “Toponium” is real!
Of all the particles in the Standard Model, the heaviest one is also the shortest-lived: the top quark (and antiquark), which lives for just half a yoctosecond. Because of this short lifespan, it was predicted that the top quark could never bind together with other quarks. However, scientists have confirmed it actually can! New results at the LHC demonstrate that toponium exists.
ASK ETHAN
Ask Ethan: Can we fix the worst prediction in all of science?
Scientists’ calculations for the zero-point energy of the quantum vacuum yield a nonsensical answer that would destroy the Universe nearly instantly. While some hypothesized a zero value due to an unknown symmetry, and others a small non-zero value due to a multiverse, the discovery of dark energy confirms a small, positive, non-zero value for the energy of empty space. But this only deepens the puzzle; it remains unsolved.
If you have a burning question about the Universe,
email startswithabang@gmail.com!
JAMES WEBB SPACE TELESCOPE
Did JWST catch the Ring Nebula forming new planets?
New images from JWST have revealed dust and chemical compounds in the center of a nearby Ring Nebula. These features resemble those of planets being born. Does this mean planetary nebulae make planets, too? Let’s dive in.
THE PODCAST
Starts With a Bang podcast #119 – The CMB
The relic signal that first proved the Big Bang has been known and analyzed for 60 years. Many think that the story of the CMB ended with Planck, but the past decade has shown that so much more remains to be discovered; however, that couldn’t be further from the truth. Come join us on the frontiers in this fascinating CMB-focused podcast episode!
INTERSTELLER INTERLOOPER
Humanity’s third interstellar object, 3I/ATLAS, is arriving now
Our Solar System travels through the Milky Way, which isn’t just full of stars and stellar systems, but a mix of rocky and icy objects, as well: purely interstellar objects. Occasionally, one of them will pass through our Solar System, like ‘Oumuamua and Borisov have previously. Now, with the discovery of 3I/ATLAS, our third, largest, and oldest interstellar object has finally arrived.
Ethan Siegel, Ph.D., is an award-winning theoretical astrophysicist who's been writing Starts With a Bang since 2008. You can follow him on Twitter @StartsWithABang.
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