On May 9th, the planet Mercury will pass in front of the sun, producing an inky-black spot on the solar disk. Catch it live on the Internet, courtesy of the Coca-Cola Space Science Center in Columbus, Georgia.
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SOLAR SECTOR BOUNDARY CROSSING: On April 29th or 30th, Earth will cross a fold in the heliospheric current sheet--a vast wavy structure in interplanetary space separating regions of opposite magnetic polarity. This is called a "solar sector boundary crossing," and it could trigger geomagnetic activity around Earth's poles. NOAA forecasters estimate a 60% chance of G1-class geomagnetic storms when the crossing occurs. Aurora alerts: text or voice
"SPACE LIGHTNING" OVER TEXAS: You know what comes out of the bottom of thunderstorms: lightning. On April 27th, Kevin Palivec of Hawley, Texas, saw something coming out of the top. "Storms moving across Texas produce more than just rain, wind, hail and tornadoes!" says Palivec. "They also produce a lot of space lightning called 'sprites.' This is a stacked image of all the sprites I caught over storms as they moved across Texas towards Dallas/Ft Worth--with one meteor thrown in!"
Because sprites are associated with thunderstorms, they tend to occur in late spring and summer. Palivec's photo shows that sprite season is now underway.
Sprites are a true space weather phenomenon, inhabiting the upper reaches of Earth's atmosphere alongside noctilucent clouds, meteors, and some auroras. Some researchers believe they are linked to cosmic rays: subatomic particles from deep space striking the top of Earth's atmosphere produce secondary electrons that, in turn, could provide the spark that triggers sprites.
"Sprites develop in mid-air very high above Earth's surface, around 80 km altitude, growing in both directions, first down, then up," says explains lightning scientist Oscar van der Velde of the Technical University of Catalonia, Spain. "An individual sprite lasts only around 5-50 milliseconds but a sequence of them can be seen to 'dance' over storm fronts for a much longer period of time."
Although sprites have been seen for at least a century, most scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now "sprite chasers" routinely photograph sprites from their own homes. Give it a try!
Realtime Sprite Photo Gallery
PENGUINS SERENADE AURORAS: As northern summer approaches, the midnight skies of the Arctic Circle are no longer completely dark. Aurora season is therefore shifting from north to south. For the next four months or so, the velvety-dark skies of Antarctica are the perfect backdrop for auroras. Penguins on the Brunt Ice Shelf serenaded this display on April 16th:
"I camped out in the field, enduring temperatures around -32°C to -34°C to witnessthis fantastic glow of green and purple," says photographer Greig Lawson. "This is at the site of an Emperor penguin colony. The calls of the birds in the background provided the soundtrack to the evening's photography!"
Lawson is a medical doctor working at the British Antarctic Survey's Halley Research Station. Located atop the Brunt Ice Shelf, a 130 meter thick slab of frozen water that floats atop the Weddell Sea, Halley is known for its studies of ozone, cosmic rays, and climate change. Lawson will be busy in the months ahead tending to the station's wintertime staff of 16. Hopefully, he'll have time send more pictures as geomagnetic storms paint their colors on Antarctic skies. Aurora alerts: text or voice
Realtime Aurora Photo Gallery
Realtime Space Weather 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 Apr. 29, 2016, the network reported 11 fireballs.
(10 sporadics, 1 beta Pegasid)
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 April 29, 2016 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.
| ||Cosmic Rays in the Atmosphere |
These measurements are based on regular space weather balloon flights: learn more.
|Situation Report -- Oct. 30, 2015 ||Stratospheric Radiation (+37o N) |
|Cosmic ray levels are elevated (+6.1% above the Space Age median). The trend is flat. Cosmic ray levels have increased +0% in the past month. |
|Sept. 06: 4.14 uSv/hr (414 uRad/hr) |
|Sept. 12: 4.09 uSv/hr (409 uRad/hr) |
|Sept. 23: 4.12 uSv/hr (412 uRad/hr) |
|Sept. 25: 4.16 uSv/hr (416 uRad/hr) |
|Sept. 27: 4.13 uSv/hr (413 uRad/hr) |
|Oct. 11: 4.02 uSv/hr (402 uRad/hr) |
|Oct. 22: 4.11 uSv/hr (411 uRad/hr) |
Approximately once a week, Spaceweather.com and the students of Earth to Sky Calculus fly "space weather balloons" to the stratosphere over California. These balloons are equipped with radiation sensors that detect cosmic rays, a surprisingly "down to Earth" form of space weather. Cosmic rays can seed clouds, trigger lightning, and penetrate commercial airplanes. Our measurements show that someone flying back and forth across the continental USA, just once, can absorb as much ionizing radiation as 2 to 5 dental X-rays. For example, here is the data from a flight on Oct. 22, 2015:
Radiation levels peak at the entrance to the stratosphere in a broad region called the "Pfotzer Maximum." This peak is named after physicist George Pfotzer who discovered it using balloons and Geiger tubes in the 1930s. Radiation levels there are more than 80x sea level.
Note that the bottom of the Pfotzer Maximim is near 55,000 ft. This means that some high-flying aircraft are not far from the zone of maximum radiation. Indeed, according to the Oct 22th measurements, a plane flying at 45,000 feet is exposed to 2.79 uSv/hr. At that rate, a passenger would absorb about one dental X-ray's worth of radiation in about 5 hours.
The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.
| ||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 |