Learn to photograph Northern Lights like a pro. Sign up for Peter Rosen's Aurora Photo Courses in Abisko National Park, winner of the TripAdvisor Certificate of Excellence Award 2015. | | |
INCREASING CHANCE OF FLARES: Sunspot AR2415 is increasingly active on Sept.17th and appears poised to produce a moderately strong M-class solar flare. Any eruptions today would be geoeffective because the sunspot is facing Earth. Solar flare alerts: text or voice
SOLARSAURUS: An enormous cloud of plasma is rotating into view over the sun's eastern limb. Astrophotographer Alan Friedman calls it "solarsaurus." He took this picture from his backyard in Buffalo, NY, on Sept. 16th:
The dino-shaped cloud is held above the surface of the sun by solar magnetic fields. Stretching more than 600,000 km from end to end, it is truly enormous, by far the largest structure on the sun today.
Astronomers call this kind of magnetized cloud a "hedgerow prominence." NASA and Japanese space telescopes have taken high resolution images of of similar prominences and seen some amazing things such as (1) tadpole-shaped plumes that float up from the base of the prominence; (2) narrow streams of plasma that descend from the top like waterfalls; and (3) swirls and vortices that resemble van Gogh's Starry Night.
Got a solar telescope? Take a look!
Realtime Space Weather Photo Gallery
DRONE-BOW: To see a rainbow, all you need are sunlight and falling rain. Correction: that's all you need to see half a rainbow. Typical rainbows are at least 50% hidden below the horizon.To see a complete rainbow, you also need a drone. Witness this picture taken by a drone over the Netherlands on Sept. 16th:
The drone's master is photographer Martijn Harleman. He explains what happened: "Just after a short rain shower, the sun peeked through. With still some drops still falling I quickly launched my drone. As the drone ascended, the full circle showed up. I stitched together 17 pictures to capture (almost) the whole phenomenon."
The drone view illustrates another common yet frequently overlooked aspect of rainbows. They are double. The interior or "primary rainbow" is caused by one reflection inside raindrops. The exterior or "secondary rainbow" is caused by two reflections. Turns out, you can learn a lot about rainbows by flying a drone.
Realtime Space Weather Photo Gallery
SUNDIVING COMET DESTROYED: The solar system now has one less comet. Earlier today, a sundiving comet discovered on Sept. 15th by Worachate Boonplod, a science writer from Thailand, passed too close to the sun and apparently evaporated. A coronagraph onboard the Solar and Heliospheric Observatory (SOHO) recorded the death plunge:
One comet went in, no comets came out. Fierce heat from the sun likely evaporated the comet's fragile ices, transforming it into a diaphanous cloud of gas and dust.
Sundiving comets are more common than you might think. SOHO has found more than 3000 of them. Most are members of the Kreutz family. Kreutz sungrazers are fragments from the breakup of a single giant comet many centuries ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail. Kreutz fragments pass by the sun and disintegrate almost every day. Most, measuring less than a few meters across, are too small to see, but occasionally a bigger fragment like this one attracts attention.
Realtime Aurora Photo Gallery
Realtime Sprite Photo Gallery
Realtime NLC Photo Gallery
Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.
On Sep. 17, 2015, the network reported 28 fireballs.
(27 sporadics, 1 September epsilon Perseid)
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]
Potentially Hazardous Asteroids (
PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding
new ones all the time.
On September 17, 2015 there were potentially hazardous asteroids.
Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach. | The official U.S. government space weather bureau |
| The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| 3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| Realtime and archival images of the Sun from SOHO. |
| from the NOAA Space Environment Center |
| the underlying science of space weather |
| Web-based high school science course with free enrollment |