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PLUTO IS NO LONGER A PINPRICK: For 85 years, dwarf planet Pluto has been little more than a feeble pinprick of light in the telescopes of Earth. Even the Hubble space telescope could barely resolve Pluto's circular shape. Now that has changed. NASA's New Horizons spacecraft is approaching Pluto, and it is seeing features on the tiny planet's surface: full story.
QUIET SUN: Everyone knows that high solar activity has a profound effect on the space around Earth. Less well known is that *low* solar activity can be equally transformative. This week, the sun is plunging into a quiet state with almost no sunspots. Only a few dark cores are peppering the face of the sun, and they are so small you might have trouble finding them in this April 30th image from the Solar Dynamics Observatory:
Almost no sunspots = almost no solar activity. The sun's X-ray output has flatlined, and NOAA forecasters estimate a scant 1% chance of strong flares in the next 24 hours. If the sunspot number continues to drop, the sun could become completely blank. The downturn is only temporary--a new batch of sunspots will probably appear by week's end--but it is significant. Spotless suns are a sign that Solar Max is ending. Stay tuned for ... quiet? Solar flare alerts: text, voice.
Realtime Space Weather Photo Gallery
MICROBES TRAVEL TO THE EDGE OF SPACE, CRASH-LAND: In an ongoing series of high-altitude balloon flights, Spaceweather.com and the students of Earth to Sky Calculus have been stress-testing halobacteria, an extremophile with an appetite for salt and UV rays. Here are some samples on April 28th, more than 100,000 feet above Earth's surface, absorbing 40x more cosmic radiation than control samples back home:
Repeatedly, the students have cultured these microbes and found that near-space flight agrees with them. For instance, the pink film in this petri dish are colonies of flown halobacteria, thriving post-flight.
Now, however, the students have found something that halobacteria cannot survive. A crash landing:
Two of the three test tubes shattered when they came down on a bed of sharp volcanic rock in the foothills of California's White Mountains. Talk about an unlucky break.
The test tubes were carrying microbes that had been aloft before--part of an experiment to see if halobacteria can survive multiple trips to the stratosphere. This is of interest to astrobiologists because conditions in Earth's stratosphere (temperature, pressure and radiation) are remarkably similar to the surface of Mars. If halobacteria can survive 100,000 feet above Earth, they might be able to survive on the Red Planet, too.
Now the payload is being re-designed to improve the cushioning of the test tubes, and soon a new batch of microbes will be flown to reboot and resume the research. After all, you can't keep a good extremophile down....
HOW DO WE PAY FOR THIS? All of the high-altitude balloon research featured on Spaceweather.com is crowd-funded, mainly by ordinary people and small businesses. The April 28th flight, for instance, was sponsored by a sail-cloth company in Hawaii. They donated $500 and, in return, we flew their logo to the edge of space: image. Would you like to become a sponsor? Contact Dr Tony Phillips for details.
VOLCANIC GAS CROSSES THE ATLANTIC: European MetOp satellites have been monitoring aerosols blasted into the atmosphere by Chile's Calbuco volcano on April 22nd. A new 8-day movie shows a plume of sulfur dioxide (SO2) crossing the Atlantic from South America to Africa:
Credit: The Global Ozone Monitoring Experiment-2 (GOME-2) onboard MetOp-A and MetOp-B
South Africans should be alert for "volcanic sunsets" in the evenings ahead when the plume reaches the tip of their continent.
When the plume crossed Brazil, it produced "an impressive display of bright exotic colors in the evening twilight sky," reports Helio C. Vital of Rio de Janeiro, Brazil. This is what he saw on April 27th:
Many of Vital's photos show a distinctly purple hue. That is one of the telltale signs of a volcanic sunset. Fine volcanic aerosols in the stratosphere scatter blue light which, when mixed with ordinary sunset red, produces a violet hue. But purple isn't the only thing to look for, says atmospheric optics expert Les Cowley. In addition, he advises, sky watchers should "be alert for a very bright yellow twilight arch, fine cloud structure in the arch seen through binoculars, and long diffuse rays and shadows."
South African sunsets will probably be less vivid than their Brazilian counterparts, because the plume has spread out during its transit across the Atlantic. Stay tuned for updates.
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. 30, 2015, the network reported 14 fireballs.
(13 sporadics, 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 30, 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 |