Spotless Days Current Stretch: 0 days 2016 total: 20 days (9%) 2015 total: 0 days (0%) 2014 total: 1 day (<1%) 2013 total: 0 days (0%) 2012 total: 0 days (0%) 2011 total: 2 days (<1%) 2010 total: 51 days (14%) 2009 total: 260 days (71%) Updated 07 Sep 2016
Geomagnetic Storms: Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2016 Sep 07 2200 UTC
Wednesday, Sep. 7, 2016
What's up in space
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ASTEROID FLYBY (UPDATED): Newly discovered asteroid 2016 RB1 flew past Earth on Sept 7th, only 25,000 miles above our planet's south pole. Because of the asteroid's southern trajectory, it did not pass within the orbits of any communication or weather satellites. Researchers say the space rock is 25 to 50 ft in diameter, or about the size of a grey whale. According to a NASA ephemeris, 2016 RB1 will pass the Moon on Sept. 8th at a distance of approximately 179,000 miles--a rare double flyby of the Earth-Moon system.
Ernesto Guido used a remotely-controled telescope in Siding Spring, Australia, to photograph the flyby:
"This is a 60 second exposure with a 0.4 meter reflecting telesope," says Guido. "At peak brightness, the asteroid shone like a star of 12th magnitude."
Asteroid 2016 RB1 was discovered on Sept. 5th by astronomers using the 60-inch Cassegrain reflector telescope of the Catalina Sky Survey, located at the summit of Mount Lemmon in the Catalina Mountains north of Tucson, Arizona. More images of the asteroid may be found in the realtime photo gallery:
WHY ARE JUPITER'S AURORAS SO RED? Many readers have asked why Jupiter's auroras, described in a news item below, are so impressively red. In fact, they are infra-red. Juno science team member Alberto Adriani explains:
"The colors of auroras are determined by the gas that is present in the atmosphere. On Earth the gas generating the beautiful red or green auroras is oxygen. On Jupiter, the atmospheric gas is hydrogen. Two distinct auroras coexist over the poles of Jupiter: Ultraviolet auroras created by hydrogen in its molecular form (H2) and infrared auroras created by the hydrogen ion H3+."
AURORAS ON JUPITER: On Aug. 27th, for the first time ever, NASA's Juno spacecraft swooped over Jupiter's south pole. The flyby revealed an astonishing vortex of infra-red light:
"While we knew that the flyby of Jupiter's south pole might reveal the planet's southern aurora, we were still amazed to see it for the first time," says Alberto Adriani from the Istituto di Astrofisica e Planetologia Spaziali in Rome. Adriani is a co-investigator on the Jovian Infrared Auroral Mapper (JIRAM), the instrument that took the picture.
Another instrument on Juno named "Waves" detected low-frequency (<100 kHz) radio signals coming from Jupiter's aurora-zone. To make these signals audible, mission scientists at the University of Iowa shifted the signals into the frequency range of human hearing. The audio begins about 30 seconds into this movie:
If the auroras of Jupiter sound mysterious--that's because they are.
Unlike Earth, which lights up in response to solar activity, Jupiter makes its own auroras. The power source is the giant planet's own rotation. Although Jupiter is ten times wider than Earth, it manages to spin around 2.5 times as fast as our little planet. As any freshman engineering student knows, if you spin a magnet you've got an electric generator. And Jupiter is a very big magnet. Induced electric fields accelerate particles toward Jupiter's poles where the aurora action takes place. Remarkably, many of the particles that rain down on Jupiter's poles appear to be ejecta from volcanoes on Io. How this complicated system actually works is a puzzle.
Stay tuned for more space weather reports from Jupiter as Juno continues its explorations of the giant planet. Solar flare alerts: text or voice
DIAMOND DUST ICE HALOS IN ANTARCTICA: In the icy lands around the south pole, ordinary things take on an exotic quality. Count sundogs among them. B. Sudarsan Patro photographed these from the Bharati Indian Base Station in the Larsemann Hills of Antarctica on Sept. 5th:
Sundogs--that is, rainbow colored splashes of light on either side of the sun--are seen around the world on a daily basis. They are caused by ice crystals in high cirrus clouds.
Ice crystals in the air around Antarctica, however, are special. They are "diamond dust." These tiny, jewel-like crystals of ice form on cold days in the air near ground level. When they catch the rays of the low-hanging sun, the results can be spectacular, with sundogs that glitter intensely as the dust drifts by. A close up of Patro's sundogs shows this effect in action:
Each speck and circle of light in this image is sunlight glistening through an individual crystal of diamond dust.
"Sept. 5th marked the Ganesh Chatrurthi, the Hindu festival in honor of the elephant-headed god, Ganesha," says Patro. "We went outside to celebrate and saw this diamond dust halo in the sky. It was wonderful."
For more wonderful shots from around the world, browse the realtime photo gallery:
Updated: Sept.3, 2016 // Next Flight: Sept. 10, 2016
Sept. 3, 2016: On Sept. 2nd, Spaceweather.com and the students of Earth to Sky Calculus conducted a successful transcontinental launch of two space weather balloons--one from New Hampshire and another from California. The New Hampshire balloon recorded the highest levels of atmospheric radiation since our monitoring program began two years ago. Students are reducing the data now, and we will report the results in the coming week.
While you wait, here is a shot of the Atlantic coast of Maine taken during the Sept. 2nd balloon flight from an altitude of 118,000 feet:
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. Furthermore, there are studies ( #1, #2, #3, #4) linking cosmic rays with cardiac arrhythmias and sudden cardiac death in the general population. Our latest measurements show that cosmic rays are intensifying, with an increase of almost 13% since 2015:
Why are cosmic rays intensifying? The main reason is the sun. Solar storm clouds such as coronal mass ejections (CMEs) sweep aside cosmic rays when they pass by Earth. During Solar Maximum, CMEs are abundant and cosmic rays are held at bay. Now, however, the solar cycle is swinging toward Solar Minimum, allowing cosmic rays to return. Another reason could be the weakening of Earth's magnetic field, which helps protect us from deep-space radiation.
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 data points in the graph above correspond to the peak of the Reneger-Pfotzer maximum, which lies about 67,000 feet above central California. When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles that is most intense at the entrance to the stratosphere. Physicists Eric Reneger and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.
THIS RESEARCH IS CROWD-FUNDED: The cosmic ray research presented on Spaceweather.com is done by students, driven by curiosity, and funded entirely by readers. Our latest flight over California on Aug. 21st was sponsored by World Tech Toys of Valencia CA. In exchange for their generous donation of $750, we flew a toy Striker Drone to the edge of space:
HD video and poster-quality images of the drone in space are now being used by World Tech Toys for marketing and outreach--an out-of-this-world bargain.
Our next flights on Sept. 2nd and Sept. 10th need sponsors. Would you like to assist? Contact Dr. Tony Phillips to make arrangements.
All Sky Fireball Network
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 Sep. 7, 2016, the network reported 41 fireballs. (38 sporadics, 1 September epsilon Perseid, 1 alpha Aurigid, 1 Northern iota 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]
Near Earth Asteroids
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 September 7, 2016 there were 1730 potentially hazardous asteroids.