When is the best time to see auroras? Where is the best place to go? And how do you photograph them? These questions and more are answered in a new book, Northern Lights - a Guide, by Pal Brekke & Fredrik Broms.
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THE FIRST MAGNETIC STORM OF SUMMER, DELAYED: A CME expected to hit Earth's magnetic field on June 22nd is overdue. However, NOAA forecasters believe it is merely late, not off-target. Minor geomagnetic storms are possible on June 23rd when the CME finally arrives. Aurora alerts: text, voice
TRIPLE RING AROUND THE SUN: Regular sky watchers are accustomed to seeing rings of light around the sun. Called "ice halos," they form when sunlight shines through ice crystals in high clouds. Usually these rings appear one at a time. On June 21st, Jun Lao of Mason, Ohio, saw three at once:
"It was about 4 p.m. EDT in the greater Cincinnati area when I imaged what I first thought was a regular halo, but was surprised to see three concentric halos!" says Lao. "The sky had a light cloud layer, and I suspect these multiple halos were caused by pyramidal ice crystals."
Indeed, they were. Ordinary sun halos are produced by crystals shaped like pencils and flat plates. On rare occasions, however, the sky fills with pyramidal crystals. They look like two pyramids glued together, base-to-base. The pyramid-tips are sometimes truncated, and sometimes the two pyramids are separated by an intervening prism section, creating 18 different variations with up to 20 sides. Such a complicated crystalline form can produce multiple halos during the same display.
These multiple halos are sometimes called "odd-radius halos." However, as atmospheric optics expert Les Cowley points out, "Odd radius halos are perhaps not so 'odd' or rare as usually thought. Make a point of routinely searching for them."
Realtime Space Weather Photo Gallery
SPACE WEATHER BUOY TAKES SELFIE: Assisted by the students of Earth to Sky Calculus, spaceweather.com has been launching a series of Space Weather Buoys to measure cosmic radiation in the stratosphere. A buoy consists of an insulated payload (a.k.a. K-Mart lunchbox) bristling with sensors and cameras, carried aloft by a suborbital helium balloon. On the latest flight, June 19th, the payload took a selfie. Here it is flying 95,000 feet above Earth's surface:
The "SelfieCam" was designed by high school student Carson Reid. It is shown here held up for inspection by launch team member Amelia Koske-Phillips.
The goal of the ongoing experiment is to determine how radiation levels change during solar and geomagnetic storms, and how those changes affect the ozone layer. During each flight, the buoy gathers a complete radiation profile starting at the launch site in California's Eastern Sierras and extending up to 100,000+ feet. Such data are of interest to aviators, entrepreneurs in the emerging space tourism industry, and researchers of the ozone layer. Selfies are a visual bonus.
A complete data set will be released in Oct. 2014 when the student scientists will have collected a full year of radiation measurements, spanning all four seasons and a variety of space weather conditions. Stay tuned.
See also: "Teens launch balloons to the Edge of Space" from the LA Times
ELECTRIC-BLUE SUMMER CLOUDS: Noctulicent clouds (NLCs) are a phenomenon of summer. Ironically, that is when the top of Earth's atmosphere is cold enough to form ice crystals around meteor smoke--the "stuff" of NLCs. So, you know the summer solstice has arrived when the evening sky starts to look like this:
"This fine display of NLCs lasted a number of hours and was visible all across Northern Ireland," says photographer Andy McCrea of Bangor in County Down. "These pictures were taken around 3am on June 20th."
Mark McKenna of Maghera, Northern Ireland, also saw the clouds' signature electric-blue ripples. "This absolutely spectacular noctilucent cloud display was one of the best I have seen in years," he says. "The NLCs were beautiful, glowing vivid white then blue. Of note were the graceful whirls, herringbone, sharp bands and lacunosus holes, the NLCs were even casting shadows onto other NLC forms."
Long ago, NLCs were confined to the Arctic, but in recent years they have been sighted as far south as Colorado and Utah. Some researchers think the increasing visibility is a sign of climate change. Whatever the cause, sky watchers should be alert for NLCs as northern summer unfolds.
Observing tips: Look west 30 to 60 minutes after sunset when the Sun has dipped 6o to 16o below the horizon. If you see luminous blue-white tendrils spreading across the sky, you may have spotted a noctilucent cloud.
Realtime NLC Photo Gallery
Realtime Aurora Photo Gallery
Realtime Comet 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 Jun. 23, 2014, the network reported 4 fireballs.
( 4 sporadics)
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 June 23, 2014 there were 1483 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters: 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.
|Asteroid || |
|2014 MP || |
|2013 AG69 || |
|2011 PU1 || |
|2002 JN97 || |
|2001 RZ11 || |
|2013 WT67 || |
| ||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 |