Space Weather Update: 02/28/2017
By Spaceweather.com, 02/28/2017
SUNSET PLANETS: When the sun goes down tonight, step outside and look west. The skinny crescent Moon is shining alongside Venus in the twilight sky. Got a small telescope? Point it at Venus. The planet has phases, and it is a crescent, too! Sky maps: Feb. 28, Mar. 1.
SOLAR WIND, INCOMING: A canyon-shaped hole in the sun's atmosphere is spewing a stream of solar wind toward Earth. Polar geomagnetic storms could begin as early as Feb. 28th when the leading edge of the stream reaches our planet. NOAA forecasters estimate a 60% chance of G1-class storms on March 1st when Earth is fully enveloped by the fast-moving solar wind.
The source of the solar wind is a coronal hole (CH)--a region in the sun's atmosphere where the magnetic field opens up and allows solar wind to escape. NASA's Solar Dynamics Observatory photographed the structure, above, on Feb. 27th. Researchers call this a "negative-polarity" coronal hole because it contains south-pointing (that is, "negative") magnetic fields that tend to be very effective in causing geomagnetic storms when they reach Earth. Arctic sky watchers should be alert for bright auroras in the nights ahead. Free: Aurora alerts.
SOUTHERN HEMISPHERE SOLAR ECLIPSE: On Sunday, Feb. 26th, the Moon passed in front of the sun, off-center, transforming the solar disk into a crescent across much of Earth's southern hemisphere. Oleg Toumilovitch sends this picture from Johannesburg, South Africa:
"I caught the last moments of the eclipse just before sunset," says Toumilovitch.
While hundreds of millions of people witnessed a crescent sun, a much smaller number saw the "ring of fire." In a narrow path stretching across the southern reaches of South America and parts of Africa, the Moon passed directly in front of the sun, covering 99% of the solar disk. This allowed a fiery annulus of solar plasma to circumscribe the mountainous limb of the Moon.
Petr Horalek photographed the deep annular eclipse from Facundo, Argentina:
A full-sized image clearly shows the ring-shaped sun.
"What a wonderful experience," says Horalek. "In Patagonia, we witnessed the deep and incredibly short annular solar eclipse (duration about 47 sec.) in a blue sky with absolutely no cloud! The eclipse was so deep that the environment grew darker and all the shadows were drab. The place we chose was just a few dozens of meters from pleasant campsite, on the shore of small river close to Facundo village in Chubut, Argentina."
ARCTIC SPACE REINDEER: The students of Earth to Sky Calculus are about to travel inside the Arctic Circle (Abisko, Sweden) for their first polar space weather balloon launch. To raise money for the trip, on Feb. 23rd they flew a payload-full of Arctic reindeer pendants to the edge of space:
You can have one for $129.95. Each glittering pendant comes with a greeting card showing the jewelry in flight and certifying that it has been to the stratosphere and back again. These pendants make great Birthday and Mother's Day gifts.
Bonus: Would you like your pendant to be flown over the Arctic as well? Make a note to that effect in the COMMENTS box at checkout, and we will take your pendent to Sweden for a second trip to the stratosphere.
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 Feb. 27, 2017, the network reported 9 fireballs.
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 February 28, 2017 there were 1775 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
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
Readers, thank you for your patience while we continue to develop this new section of Spaceweather.com. We've been working to streamline our data reduction, allowing us to post results from balloon flights much more rapidly, and we have developed a new data product, shown here:
This plot displays radiation measurements not only in the stratosphere, but also at aviation altitudes. Dose rates are expessed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x. These measurements are made by our usual cosmic ray payload as it passes through aviation altitudes en route to the stratosphere over California.
What is this all about? 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 more than 12% 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.
Daily Sun: 28 Feb 17
These sunspots have stable magnetic fields that pose almost no threat for strong flares. Credit: SDO/HMI
Sunspot number: 40
What is the sunspot number?
Updated 28 Feb 2017
Current Stretch: 0 days
2017 total: 11 days (21%)
2016 total: 32 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 28 Feb 2017
The Radio Sun
10.7 cm flux: 82 sfu
explanation | more data
Updated 28 Feb 2017
Current Auroral Oval:
Coronal Holes: 28 Feb 17
Solar wind flowing from the indicated coronal hole should reach Earth on Feb. 28-March 1. Credit: NASA/SDO.
Noctilucent Clouds The southern season for noctilucent clouds began on Nov. 17, 2016. Come back to this spot every day to see the "daily daisy" from NASA's AIM spacecraft, which is monitoring the dance of electric-blue around the Antarctic Circle.
Updated at: 02-24-2017 17:55:02
Updated at: 2017 Feb 27 2200 UTC
Updated at: 2017 Feb 27 2200 UTC