Of Particular Significance

Category: Geology

I hope many of you saw auroras (northern lights) last night! I briefly saw the strongest steady red glow I myself have ever observed, visible even amid street lights and my neighbors’ house lights.

The skies, shown only slightly brighter than to the naked eye, as seen at 8pm Boston time. Credit: Matt Strassler

Then, after a break as some clouds rolled in, we were graced with a few hours of mostly diffuse green glow with patches of dim but distinct red that would come and go. All these colors were visible with the naked eye, albeit much less bright than shown in photos. It was quite a storm, not as violently active as the one earlier this year, but very persistent.

The storm lasted all night, though the auroras varied greatly in brightness. Data from https://www.swpc.noaa.gov/

I also tried to find Comet A3 just after sunset, but failed, even with the help of binoculars. Apparently the brief spike in its brightness, due to “forward scattering” as it passed between us and the Sun, may have died off too quickly, leaving it impossible to see in early twilight. It will become dimmer day by day, but it will also be visible later each evening, and at some point should become easy to see in dark skies. Let me know when you first observe it!

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON October 11, 2024

It could be quite a night!

A powerful solar flare (an explosion on the Sun) about 36 hours ago created a large and fast coronal mass ejection (a cloud of subatomic particles heading away from the Sun) that is due to arrive at Earth in the next few hours (it will show up less than an hour before it arrives as chaos in this data.) UPDATE: IT HAS ARRIVED; IF IT’S DARK WHERE YOU ARE, GO LOOK. That could mean problems for the electrical grid. It could also mean strong auroras (northern and southern lights) far from the poles. The timing, if correctly predicted, is such that Asia and Europe may have the best chances, but the auroras could potentially last until it is dark in the Americas too.

Also, just after sunset tonight, we may with difficulty be able to see Comet A3 (short for Comet C/2023 A3 Tsuchinshan-ATLAS ). The comet is bright — some reports give it a brightness comparable to the planet Venus, although more diffuse — but so is twilight. UPDATE: I HAVE BEEN WARNED THAT THE RAPID BRIGHTNING PERIOD, DUE TO A LIGHT SCATTERING EFFECT, MAY ALREADY BE OVER. IF SO, THE STATEMENTS HERE MAY BE TOO OPTIMISTIC. The comet is roughly ten Sun-widths above and slightly to the right of the Sun, and should be visible 15-30 minutes after sunset if you have a low and mostly cloudless horizon. Best bet is to bring binoculars and scan the sky; you’ll notice it much more easily, even if it is visible to the naked eye.

Each day following, the comet will be higher in the sky at sunset, making it more visible in late twilight, but it will also become intrinsically dimmer. Experts seem to disagree about when it will be at its best, but this weekend should be good, if not before.

Added 5pm NYC time : Here’s what the data looked like showing the arrival of the coronal mass ejection, a few hours ago, at the ACE satellite, which gives us about an hour’s warning here on Earth:

Added 5pm NYC time: Here’s what the data looks like showing an ongoing geomagnetic storm and likely auroras; warning, the data is delayed 3 hours, so it’s not showing you what’s happening right now. “UTC” is 5 hours ahead of New York (i.e. Eastern) time, one hour behind Central European time.

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON October 10, 2024

A busy news week: a Nobel prize, another chance of auroras, and… a comet. It’s probably not the comet of the century, but comets like this one show up only about once every ten years. This one has already been visible in early morning skies. This week it enters our evening skies, and will likely be a lovely sight after dark for the rest of October.

Day by day, the comet will move up and to the left, beginning at the Sun’s right. Look there once the Sun is significantly below the true horizon and the sky has darkened a bit.

Later in the month it will be visible longer into the evening, but much less bright.

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Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON October 8, 2024

[Update: one coronal mass ejection arrived very early Sunday morning. But the impact seems to have been weak, with no auroras resulting. Aurora forecasting is still not very accurate… these solar flares were very big, but nevertheless, didn’t do much for us yet, and it’s getting late…]

Quick note: two powerful solar flares occurred in the last 72 hours, creating high spikes in the rate of X-rays from the Sun.

Each flare created a coronal mass ejection that could arrive in a couple of days at Earth, potentially creating a geomagnetic storm. Consequently there’s a good probability this weekend, especially Saturday night into Sunday morning (in Europe and the US), of seeing northern and southern lights (auroras). [See this post for some advice as to how to infer whether the storms have started and/or are ongoing.]

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON October 4, 2024

This is my second post on the subject of why “the speed of light (in empty space)”, more accurately referred to as “the cosmic speed limit”, is so fast. This speed, denoted c, is about 186,000 miles (300,000 km) per second, which does indeed seem quick.

But as I pointed out in my first post on this subject, this isn’t really the right question, because it implicitly views humans as centrally important and asks why the cosmos as strange. That’s backward. We should instead ask why we ourselves are so slow. Not only does this honor the cosmos properly, making it clear that it is humans that are the oddballs here, this way of asking the question leads us to the answer.

And the answer is this: ordinary atomic material, from which we are made, is fragile. If a living creature were to move (relative to the objects around it) at speeds anywhere close to c, it couldn’t possibly survive its first slip and fall, or its first absent-minded collision with a door frame.

Today I’ll use a principled argument, founded on basic particle physics and its implications for atomic physics, to show that any living creature made from atoms will inevitably view the cosmic speed limit as extremely fast compared to the speeds that it ordinarily experiences.

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Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON October 3, 2024

I’m often asked two very natural and related questions.

  1. Why is the speed of light, usually denoted c, so astonishingly fast?
  2. Why, in Einstein’s famous equation relating energy and mass — E=mc2 — does c2, a gargantuan number, appear?

It’s true that the speed of light does seem fast — light can travel from your cell phone to your eyes in a billionth of a second, and in a full second and a half it can travel from the Earth to the Moon.

And indeed the energy stored in your body is comparable to the Earth’s most explosive volcanic eruptions and to the most violent nuclear bombs ever tested — enormously greater than the energy you use to walk across the room or even to lift a heavy suitcase.

What in the name of physics — and chemistry and biology — is responsible for these bewildering features of reality? The answer is fascinating, and originates in particle physics and the resulting structure of matter. It is surprisingly intricate, though, so I’m going to approach this step-by-step over three blog posts. Here’s the first.

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Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON October 1, 2024

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