A severe geomagnetic storm has just hit Earth — which means we could see auroras tonight! Here’s what you’ll need to know.

Aurora prequel
The show has already started! On Thursday night, May 9, the first salvo arrived at Earth to spark a modest but colorful aurora. Here it meets its reflection in a lake north of Duluth, Minnesota around 11:30 p.m. CDT. The W of Cassiopeia and Perseus Double Cluster appear at upper left.
Bob King

Better plan on getting a nap this afternoon, because if it's clear tonight (May 10th), you may not get to bed until the birds sing again at dawn. The National Oceanic and Atmospheric Administration's Space Weather Prediction Center (SWPC) expects a powerful G4 storm to hit, which could bring the aurora as far south as California and Alabama in the U.S. and as far north as Sydney, Australia in the Southern Hemisphere. Folks in the northern U.S. will see the aurora expand well beyond the zenith deep into the southern sky.

During the climax of one of the more recent G4 events on April 23, 2023, intensely bright rays from every corner of the heavens converged near the zenith and flashed and twisted about like kid's kaleidoscope. I nearly died of amazement.

Giant sunspot region 3664
This past week sunspot region 3664 (lower right) rapidly grew into a behemoth some 15 times the diameter of the Earth. Seen here on May 8th, the region was easily visible through a safe solar filter with the naked eye. The highly volatile region, one of the largest of the current solar cycle, possesses a complex magnetic field that has spawned multiple M- and X-class flares.
Bob King

All the excitement stems from a volley of flares that erupted from the gigantic sunspot region 3664, which has hurled no fewer than five coronal mass ejections (CMEs) in our humble planet's direction. Some of the blasts have overtaken and merged with earlier ones to create a so-called "cannibal" CME, possessed of even greater power.

CME animation
This animation, compiled from images taken by the Solar and Heliospheric Observatory's coronagraph, show the eruption of one of the early CMEs from sunspot region 3664 on May 8th.
NASA / ESA

A high-octane storm can touch more than the human heart and soul; it can potentially affect power grids on Earth and cause disruptions in radio signals and communications systems. Satellites can experience surface charging that could potentially damage sensitive electronics.

Even astronauts aboard space stations have to take precautions. Even though the planet's magnetic field protects them to an extent, solar protons in geomagnetic storms may breach the hull, so to speak. To minimize risk, astronauts retreat to areas in the station where the surrounding mass of material offers further protection.

H-alpha solar flare
Region 3664 (center right) blew off a large flare on May 8th, as seen in this hydrogen-alpha image through a Lunt 60 mm telescope.
Bob King

Aurora Q&A

To address some of the many questions that inevitably arise when a major auroral storm is imminent, let's do a quick Q&A. Keep in mind that despite the best forecasts the aurora can still play tricks and arrive earlier or later than expected, or heaven forbid, not at all.

When should I look?
Even as I write this, the blast has already arrived. The latest SWPC forecast indicates the storm should continue into Friday night, May 10-11, as twilight descends over the U.S. and Canada. Sunsets are late this time of year so the sky won't get dark until after 9:30 p.m. local time. Generally, the closer to local midnight (1 a.m. when Daylight Saving Time is in effect) the stronger and more intense the aurora. A G3-rated (strong) storm is expected from 11 p.m. to 2 a.m. EDT which should ramp up to a G4 from 2 a.m. through dawn. Yes, the show goes on all night! It will fire up again to a G2 (moderate) level on Saturday night, May 11-12, between 10 p.m. and 1 a.m. EDT. That's great news if clouds get in your way Friday.

Where should I go to see it?
The best place to view the aurora is the most obvious one — as far as possible from city lights. If you can, drive north from your city to a location with the least amount of light pollution. Use the interactive map at lightpollutionmap.info to explore your region for potential sites. Color-coding shows where light overkill is worst — lilac, red and yellow — and where it's suitably dark — green, blue and gray. Use your mouse (or fingers) to zoom in and out of the map and change your location. If possible, scout out your chosen spot during the daytime so you're comfortable there at night. Importantly, make sure you have an open view of the northern sky (or southern sky in the Southern Hemisphere). Fields, lake shores, and hilltops are ideal.

What equipment do I need?
Good news — none! Your eyes will take it all in especially as they become increasingly dark-adapted with time spent outdoors. Other helpful items include a chair so you can sit and rest your legs if you're out a long time. A beverage and snack will be very welcome as the clock ticks toward midnight. Warm clothing is essential because you'll be standing or sitting still, frozen in awe, much of the time.

Corona aurora April 23, 2023
A dazzling coronal aurora pivots high in the sky during the G4 storm on April 23, 2023.
Bob King

Will it look like the colorful photos I see in books and online?
Generally, no. Most auroras appear pale green or white with hints of pink. Our eyes see in real time, while a camera accumulates light during a time-exposure, revealing the aurora's subtle colors more vividly. However, during powerful storms, you'll see brief bouts of intense color — purples, reds, pinks, and greens. Colors are caused by particles from the Sun spiraling down Earth's magnetic field lines and striking atoms and molecules of oxygen and nitrogen in the atmosphere. Temporarily energized by the collisions, the atoms release tiny bursts of light when they settle back to their rest states.

What causes the aurora?
In a nutshell, the magnetic field that comes along for a ride in the blast of particles released in a CME, couples with Earth's magnetic field. This creates a conduit that funnels those particles — electrons and protons — at high speed into the atmosphere over the planet's polar regions.

iPhone aurora
This is a 3-second, handheld image of the coronal aurora with an iPhone 13 made on March 23, 2023, from northern Minnesota.
Bob King

How can I photograph the aurora?
You can use your smartphone. Hold it up to the sky, and the phone will set itself to night mode, allowing handheld exposures of 3 seconds — long enough to easily capture a moderate- to bright aurora. Hold the phone to the sky, tap the shutter release button, and keep the two crosses that appear on your screen aligned. If you have a DSLR or mirrorless camera, attach it to a tripod and focus on a bright star using the camera's live view feature. A wide-angle lens is best, from 15 to 35mm. Open the lens to its lowest f-stop (f/2 or 2.8 is best if you have it) to let in the maximum amount of light. Expose at ISO 1600 or 3200 for 5-20 seconds. Check the replay to see if you're on target. If not, adjust the exposure or ISO accordingly.

How do I find out where the sky is clear if it's cloudy at my house?
Check the GOES satellite images at GOES East or GOES West (for skywatchers in the far western U.S.). Click on your location on the map for an enlarged view. To see clouds at night, click on the Choose bar and select Channel 7, the third option down. You can also go to Windy.com and click the Satellite heading for an excellent cloud map. Or just Google and download the Windy app.

What's a good aurora alert app?
SpaceweatherLive, free for Android and iPhones.

Tags

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Comments


Image of Anthony-Mallama

Anthony-Mallama

May 10, 2024 at 5:09 pm

Bob - Your pictures are fantastic!

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Bob King

May 10, 2024 at 10:05 pm

Thank you, Anthony! That's kind of you to say. I hope you have good skies for aurora-viewing tonight.

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Rod

May 11, 2024 at 10:21 am

AR3664 is one big sunspot group and active region 🙂 Observed 0900-0945 EDT 11-May-2024. This was the Carrington sunspot active reported in the news, very large sunspot documented in 1859, see attached email and ephemeris. I used 90-mm refractor with glass white light solar filter, TeleVue 40-mm and TeleVue 32-mm eyepiece for 25x to 31x views. Some cirrus did form slight obscruation layer but easy to see with many dark cores and other active region sunspots visible too. Weather mostly sunny, some cirrus, temperatue 14C, winds 340/4 knots, h=58%. Given the Sun's distance this morning AR3664 was reported to be near 200,000 km in diameter or about 4.5 arcminute angular size. Very cool to see this in my telescope views.

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Bob King

May 12, 2024 at 3:05 am

Thank you, Rod, for your detailed report. Truly an amazing group. I'm going to miss it when it rotates over the limb Sunday-Monday.

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Michael-Nakamura

May 11, 2024 at 10:11 pm

Hi Bob, I still can't believe it, but I saw a nice display last night from Arivaca, Arizona (lat. 31.5 deg. N). It started just before local midnight and lasted around 30 minutes. Mostly a vivid red glow that extended nearly 30 degrees in altitude, and punctuated with white vertical streaks. It moved slowly from northeast to northwest.

This is my third auroral sighting, but I've never seen green or purple, just red and white. Is that just me?

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Bob King

May 12, 2024 at 3:09 am

Michael,
Great to hear you saw it so far south! The reason you see red and not some of the other colors is because red (from excited oxygen atoms) occurs at very high altitudes, which places it above most of the rest of the aurora. It therefore climbs above your horizon whereas green (occurs at a relatively low altitude) sits below your horizon.

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Morgunk

May 12, 2024 at 11:22 pm

I appreciate your response. I shared a folder in my google drive. These were taken about 4:55 am
https://drive.google.com/drive/folders/1W_Ct0saVzroX2gs3j4AX-6c_T0jrqcU1

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Morgunk

May 12, 2024 at 11:25 pm

Accidentally replied in wrong place and thanks for your post. Pics are amazing and thanks for the explanation of the event. That sunspot is magnificent. I have a solar filter for my telescope which I rarely use but have never seen sunspots like those before

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Morgunk

May 12, 2024 at 11:01 pm

Hello, I was hoping someone could give me insight. I was in Maryland Friday night and it was very cloudy but I stayed up all night in hopes of catching a glimpse. About an hour before dawn. First pic I took was at 4:53 with 5:56 sunrise. The entire horizon from about nne to ese was glowing bright orange. It had the llook of a sunrise but from how bright it was that same sight would happen more like 15 minutes before dawn. From what I understand Northern lights aren’t that color orange. I’ve searched for a while looking for a solution. From the appearance it was sunrise but I didn’t think you could see sunlight that clearly an hour before dawn. It’s usually still pitch black then. Can anyone explain and/or confirm or deny that what I saw was the northern lights?

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Bob King

May 12, 2024 at 11:16 pm

John,
At your latitude the aurora likely would have been red near the horizon. In Maryland twilight would have been underway for about a half-hour, so you're right, you probably wouldn't have seen bright orange just yet. It's possible that green aurora overlapped with red to produce orange but I've only ever seen this in photos. Is there a place to view your photo?

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Morgunk

May 12, 2024 at 11:28 pm

Post went to place again. Trying it this way as a test

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