Looking for a unique Mother's Day gift? How about Space Roses? Proceeds from the sale of these far-out blooms support student space weather research.
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LYRID METEORS VS. THE FULL MOON: Earth is entering a stream of debris from Comet Thatcher, source of the annual Lyrid meteor shower. Normally, sky watchers would see 10 to 20 meteors per hour when the shower peaks during the night of April 21-22. This year, however, the Lyrids have competition. The full Moon is out tonight, too, and only the brightest Lyrids will pierce the glare.
Fortunately, there are some bright ones. Last night, NASA's network of all-sky meteor cameras caught this Lyrid fireball streaking over New Mexico, easily seen alongside the Moon:
On April 20-21, NASA cameras picked up four Lyrid fireballs over the USA. That number could increase on April 21-22 as Earth moves deeper into the debris stream of Comet Thatcher. Can the Lyrids compete with the full Moon? We will find out tonight. [sky map]
There is one way to experience this shower unmitigated by moonlight. Try listening to Space Weather Radio for live radar echoes from Lyrid meteoroids. The Moon does not affect this method of detecting meteors. Good luck!
Realtime Space Weather Photo Gallery
SPROUTING GRASS MOON: There's a full moon tonight and according to folklore it has a special name--the "Sprouting Grass Moon," so-called because it shines down on the new grasses of northern spring. This morning, John Stetson watched the Moon set behind Sebago Lake, Maine, and he saw a grass-green fringe along the top of the lunar disk:
"Earth's atmosphere, acting as a lens, distorted the color and shape of the setting moon," says Stetson. "The green rim is caused by the prismatic action of the low atmosphere."
Other folk-names for this month's full Moon include the Pink Moon, the Egg Moon, and the Fish Moon. "Sprouting Grass" is our favorite! Monitor the photo gallery for more moonshots:
Realtime Space Weather Photo Gallery
A DASH OF GREEN IN ARCTIC TWILIGHT: Around the Arctic Circle, night is vanishing as the summer sun rises over the polar realm. This is creating a short-lived mixture of colors in the sky: aurora green and twilight blue. Aleksander Chernucho sends this picture of the phenomenon from Russia's Kola peninsula:
"I think summer vacation is about to begin," says Chernucho, "because these are the last auroras of the 2015-2016 season."
Or, maybe, the second-to-last. An incoming solar wind stream on April 24-25 could add one more dash of green to the twilight before the Arctic sun finally overwhelms the Northern Lights. Monitor the aurora gallery for last-chance sightings.
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 Apr. 21, 2016, the network reported 11 fireballs.
(6 sporadics, 4 April Lyrids, 1 eta Aquariid)
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 21, 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 |