Tonight (January 13th) offers a wonderful opportunity for all of us who love the night sky, and also for science teachers. For those living within the shaded region of Fig. 1, the planet Mars will disappear behind the Moon, somewhere between 9 and 10 pm Eastern (6 and 7 pm Pacific), before reappearing an hour later. Most easily enjoyed with binoculars. (And, umm, without clouds, which will be my own limitation, I believe…)
For everyone else, look up anyway! Mars and the Moon will appear very close together, a lovely pair.
Figure 1: the region of Earth’s surface where Mars will be seen to disappear behind the Moon. Elsewhere Mars and the Moon will appear very close together, itself a beautiful sight. Image from in-the-sky.org.(more…)
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!
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.
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.
Thursday, Friday and Saturday this week, immediately after sunset and just to the right and above the Sun, comet A3 MAY be at its most spectacular. BE READY! You will need a low and rather flat horizon, and you have less than an hour to see it before it sets, too.
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.
[Second update: Sunday 9pm New York time: Auroras are being seen tonight. A bit fleeting for those of us in central New England, but they have been seen as far south as the Boston area, and are currently being seen further north.]
[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.]
In fact, it’s already here. Oh yes, it seems that 2024 may not just be the year of a terrific solar eclipse and spectacular outbursts of northern lights (and maybe, just maybe, a nova.) In morning twilight, if you live in the right latitudes, an ever-brightening comet can apparently be spotted right now. I haven’t seen it yet, but I’m hoping to get a chance.
Nothing in cometary life is guaranteed; comets can fall apart unexpectedly, or fail to brighten as expected. So far, though, Comet C/2023 A3 Tsuchinshan-ATLAS is looking promising; its tail may soon be longer than its name.
2ND UPDATE: Auroras are indeed being observed. (I myself am a bit too far south and skies are hazy, making the moonlight blinding; but I am reading reports from northern Europe.)
UPDATE: Something has happened at the ACE satellite around 2300 UTC (0100 Europe time, 7 pm New York time. See the plot added to the bottom of this post.
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Still waiting for a possible outbreak of auroras (northern/southern lights) tonight; a tremendous blast from the Sun, launched from a sunspot two days ago, is believed likely to make a glancing impact on the Earth, and to do so within the next 12 hours or so. That means a possibility of bright northern lights tonight if you’re north of, say, New York City’s latitude.
BUT always keep in mind that forecasting auroras is part science, part art, part luck. Our chances are decent, but the forecast can always be wrong.
As far as timing, the best way to monitor what’s going on, I’ve found, is to use https://www.swpc.noaa.gov/products/ace-real-time-solar-wind and look for sudden activity in multiple data channels. If that happens, then the ACE satellite (about a million miles away) has detected a sudden change in the solar wind, and a geomagnetic storm is likely to start at Earth within an hour or so.
Whether you will see auroras or not during the storm depends on how powerful it is, which determines how far from the poles the auroras will reach and how bright they will be. While the forecast is for a strong storm, we’ll just have to see…
At 2300 UTC (about one hour before this posting) you can see jumps occurred in many channels below. That means that the solar storm may begin right around now (0000 UTC, 8 pm New York Time)
Though I’ve been busy with a number of physics and writing tasks, I’ve been beefing up the “Reader Resources” section of this website, devoted to extending the experience of readers of my book. [BTW, the audiobook is due out at the end of September.]
The book has many endnotes (available separately here, in case [like me] you hate paging back and forth between the text and the endnotes, and would like to have the endnotes more easily available on a separate screen.) A number of these endnotes have asterisks, and for those endnotes I promised to provide more information here on this website. Well, that information is going up, step by step.
[Update: indeed, both meteors and auroras are visible tonight, at least as far south as Massachusetts, so residents of northern-tier states should definitely be looking!]
Tonight, if the sky is clear and dark in your vicinity, would be a good night for staying up late, going outside, and looking up. Not that it’s an exceptional night for star gazing, necessarily; I wrote “sky-gazing” for a reason. The two phenomena you’re most likely to see are much, much closer than the stars. Both occur in the Earth’s upper atmosphere, and are generated by effects that occur within the solar system (i.e., the Sun, its planets, and their neighborhood.)
The phenomena in question? Meteors, for sure; and auroras, just maybe.
As has been widely reported, Earth’s inhabitants are looking forward to a rare event in the sky. It’s a “nova”, predicted to be visible sometime in the coming weeks.
The word “nova” is simply Latin for “new.” Coined during the Renaissance, it initially meant “a new bright thingy in the sky that isn’t just another Starlink satellite.” Nowadays it means a very particular type of new bright thingy.
But let’s not confuse it with a “supernova.” That’s something different. How different?
Nova: Your house has an electrical blackout for an hour
Supernova: Your entire city goes dark for a week
Nova: A meteor kills the dinosaurs and lots of other creatures
Supernova: A meteor melts the Earth and blasts part of it skyward to create the Moon
