Aurora Encore May Follow July 4 Fireworks

July 4th fireworks at Duluth, Minnesota’s Bayfront Park. Credit: Bob King

Happy Fourth of July! I hope your day explodes with enjoyment.

Aurora time-lapse

Just don’t go to bed after the fireworks show before checking the northern sky. NOAA’s space weather prognosticators expect a small auroral storm to begin sometime tonight and continue through tomorrow night. There’s a 20% chance we’ll see action at mid-northern latitudes and a 60% chance at high latitudes, where one wonders if any auroras are seen to advantage this time of year. North of about 49 degrees north latitude, twilight lingers all night long during the summer months.

The forecasted northern lights are brought to you by a slower moving coronal mass ejection, a blast of particles from the sun usually caused by the explosive power of a solar flare.

Neighboring sunspot groups 1785 and 1787 photographed this morning with NASA’s orbiting Solar Dynamics Observatory. Credit: NASA/SDO

We may not have to wait too long for the next eruption. Sunspot group 1785, which rotated onto the sun earlier this week, is a large, complicated magnetic mess and harbors the energy to kick out powerful M-class flares. The sun’s rotation will bring it forward to face Earth more directly in the days ahead increasing the chances for more auroras.

M1.5 flare from sunspot group 1787 as it rounded the eastern limb of the sun early on the morning of July 3. Credit: NASA/SDO

Not far behind, sunspot cluster 1787 put on its own fireworks show when it first rotated around the sun’s limb early Wednesday morning, greeting astronomers with a moderate M1.5 flare.

How the sizes of Earth and moon compare to sunspots. Even an Earth-sized spot requires a telescope to see. The leader spot in the group 1785 is at least 3x larger than our planet. Credit: NASA

The big spot in 1785 is now large enough to see with the naked eye using a safe solar filter – I easily spotted it this morning as tiny dark fleck in the sun’s southeast quadrant. Sometimes we forget how big sunspots truly are. What looks like a tiny dot in a small telescope is about as big as the moon; Earth-sized spots are larger but ordinary by solar standards. This morning’s behemoth was easily thrice our planet’s diameter, and the group it belongs to spans some 8 Earth diameters.

A sunspot’s dark tone is deceiving. They only look that way because they’re 3,000 degrees cooler than the 11,000 degree photosphere, the glaring white “surface” of the sun. If we could remove the spots and see them alone against the black backdrop of outer space, they’d be much too bright to look at safely. Their size hints at the true vastness of the sun, an 863,700-mile-wide (1.4 million km) sphere of incandescent gas 4 times hotter than a handheld sparkler.

8 Responses

  1. Sean

    good eyes Bob! At age 36, couldn’t spot it naked-eye this AM, about 8. Obv quite easy in binos.

      1. Sean

        well i don’t know if that AM it was a bit smaller, or my contacts or solar filter weren’t clear enough, but using a different solar filter i was indeed able to see it – closer to midday – Friday. definitely a clear target, albeit small. perhaps it being nearer overhead may have increased the contrast as well.

        1. astrobob

          Good to know your eyes saw this too. Some filters are better than others. I have two favorite – black mylar and a #14 welder’s glass. Both are sharp.

  2. Edward M. Boll

    I was telling the children along the way home what would make for a perfect Fourth Light show, fireworks, fireflies , a lightning show and then clearing off for some Northern Lights, maybe throw in a few meteors into the mix.

  3. Aloha Astro Bob and Everyone!

    Just wanted to say MAHALO for that great time-lapse video. Where I live, the “aurora’s” or Northern Lights are never seen here (Hawaii) as far as I know.

    Which leads me to my questions…Is there such a thing as “Southern Lights”? Have the “Northern Lights” EVER been seen in Hawaii? Does the South Pole generate these “southern lights” (if they exist at all)? Just naturally curious and I love(d) watching them when in ‘full force’ (I was actually AWESTRUCK when watching) and appreciate any answers you could give me.

    I was unpleasantly surprised to see I couldn’t “click on” the ‘time-lapse’ to enlarge it to my full screen since most (ok, almost half the time if not more) of the ‘interactive’ photos usually are. Is that a function that is difficult to do, never mind…however if you can do it within 2 minutes or less…I could use it to calm some nerves in my home! Heh, ;-}

    Great blog sir!

    Aloha For Now!

    1. astrobob

      Hi Wayne,
      I’ve never heard of aurora in Hawaii but it’s possible during the most severe imaginable storm. Southern lights there are! I just wrote a blog on that very topic last week. Here it is:

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