Will there be a Northern Lights alert tonight in the wake of one of the most vivid displays of aurora for 20 years? Probably not, but there is another reason to be outside at sunset — a comet called C/2023 A3 (Tsuchinshan-ATLAS). With a naked-eye brightness and a large tail, it’s set to be equally unmissable.
Thursday, Oct. 11, was a crazy night worldwide, with a severe G4 — and possibly even the top-rated G5 — geomagnetic storm happening across the planet.
From Asia to Australia and Europe to North America, unbelievable images of stunning displays are coming from all corners of the globe. The planetary K-index reached an 8, just one shy of the top mark of Kp 9. The aurora was seen as far south as Arizona and Florida in the U.S.
There’s little chance of a repeat tonight, but tonight — Friday, Oct. 11 — is the first night to see a bright new naked-eye comet called C/2023 A3 (Tsuchinshan-ATLAS).
Here’s everything you need to know about tonight’s Northern Lights and the comet.
When And Where To See Northern Lights Tonight
Although NOAA’s Space Weather Prediction Center initially said that Oct. 11 and Oct. 12 could be high levels of geomagnetic activity, it’s now predicting just a G1 geomagnetic storm (the scale runs from G1 to G5) with a magnitude of Kp 4 (the scale runs from Kp1 to Kp9). That means only the far-north U.S. states are likely even to get a glimpse of the aurora.
However, don’t despair. Judging by the current propensity of the sun to produce X-class solar flares in recent weeks, another major geomagnetic storm could happen at any time. That goes double since the sun is inching towards “solar maximum,” its once-every-11-years peak in activity. We’ll know more about that on Tuesday, Oct. 15, when NASA and NOAA’s Space Weather Prediction Center will stage a joint press conference to discuss the current Solar Cycle 25.
Check my page, NOAA’s aurora view line for tonight, its 3-day forecast, its 30-minute forecast and its X account, where the latest updates are posted. We’ll have about 24 hours’ notice if there’s a possible repeat of the events of Oct. 10-11.
Meanwhile, another once-in-a-lifetime event is taking place — starting tonight.
When And Where To See And Photograph Comet C/2023 A3 (Tsuchinshan-ATLAS) Tonight
From Friday, Oct. 11, it should be possible to look west 45 minutes after sunset where you are in the northern hemisphere and see comet C/2023 A3 (Tsuchinshan-ATLAS) with your naked eyes.
Discovered early in 2023 by China’s Tsuchinshan Observatory and South Africa’s Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope, comet C/2023 A3 (Tsuchinshan-ATLAS) is on an 80,000-year orbit from the remote Oort Cloud that surrounds the solar system.
Tonight, comet C/2023 A3 (Tsuchinshan-ATLAS) will be very close to the western horizon, with Venus to its left. According to Sky & Telescope, it will appear between Antares, the brightest star in the constellation Scorpius, and Arcturus, the brightest star in Boötes.
You should be able to see its bright core, lowest to the horizon, with its dusty tail pointing upwards away from the horizon. That tail should be reasonably bright because it will likely reflect sunlight thanks to “forward scattering,” which will send reflected sunlight in the direction of Earth — and your eyes.
This first night will have it fighting twilight, so if you don’t see it, come back on Saturday and Sunday, when it will be both higher in the sky and visible in a darker sky.
Not only that, but a second comet has just been found — C/2024 S1 (Atlas) — which is expected to make its closest approach to Earth on Oct. 23 and have its perihelion with the sun — the closest it will get to our star — just five days later on Oct. 28. There are even suggestions that it could shine at a brightness of magnitude -8.3, which would be extraordinary.
Wishing you clear skies and wide eyes.
