Listen to radar echoes from satellites and meteors, live on listener-supported Space Weather Radio. | | |
SLIGHT CHANCE OF MAGNETIC STORMS: NOAA forecasters estimate a 20% chance of polar geomagnetic storms this weekend in response to a minor solar wind stream blowing past Earth's magnetic field. High-latitude sky watchers should be alert for auroras. Aurora alerts: text, voice
SPRITES AND GRAVITY WAVES: The sprite show continues. "Every day this week, I have been able to photograph red sprites shooting up from the tops of thunderstorms 400 miles away in Colorado, Nebraska and Kansas," reports Jan Curtis of Santa Fe, NM. On June 27th he saw something more: "At around 10:30PM MDT, gravity wave clouds developed and intensified through midnight." This snapshot shows a red sprite cutting through the green ripples:
"While I could not detect them with my unaided eyes, time lapse revealed that the waves were moving very slowly to the northeast."
The waves are, literally, the ripple effect of a powerful thunderstorm on the mesosphere some 80 km above Earth's surface. From space, these waves look like a giant atmospheric bull's eye. The green hue comes from airglow, an aurora look-alike that can be seen on very dark nights from any place on Earth.
Although airglow resembles the aurora borealis, its underlying physics is different. Airglow is caused by an assortment of chemical reactions in the upper atmosphere driven mainly by solar ultraviolet radiation. Auroras, on the other hand, are fueled by gusts of solar wind. While auroras are confined mainly to polar regions, airglow makes a luminous bubble that surrounds the entire planet.
The undulations in the airglow Curtis photographed are caused by temperature and density perturbations rippling away from the central axis of the distant thunderstorm. Speaking simplistically, those perturbations alter chemical reaction rates in the upper atmosphere, leading to more-bright or less-bright bands depending on whether the rates are boosted or diminished, respectively.
Inhabiting the upper reaches of Earth's atmosphere alongside meteors, noctilucent clouds and some auroras, sprites and mesospheric gravity waves are true space weather phenomena. Now is a good time to see them.
SOMETHING IN THE OFFING: Solar activity has been low for more than a week, but this could change as a cluster of active regions emerges over the sun's eastern limb. Towering magnetic loops shown in this June 28th UV image from NASA's Solar Dynamics Observatory herald their arrival:
The incoming sunspots include old regions AR2080, AR2082, and AR2085, which have just finished a two-week transit around the farside of the sun--a hemisphere that could soon become invisible to us because of troubles with STEREO.
NOAA forecasters have posted an escalating series of flare probabilities in response to the approaching active regions. A 5% chance of M-flares today triples to 15% by Monday. Amateur astronomers with backyard solar telescopes are encouraged to monitor developments. Solar flare alerts: text, voice
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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. 28, 2014, the network reported 20 fireballs.
( 20 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 28, 2014 there were 1486 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 |