Space Weather Update: 03/21/2017
By Spaceweather.com, 03/21/2017
SOLAR WIND ADVISORY: Arriving a day earlier than expected, a stream of solar wind is enveloping Earth’s magnetic field today. The fast-moving (600+ km/s) stream could influence our planet for the next three days with a 60% chance of G1-class geomagnetic storms between now and March 23rd. Arctic sky watchers should be alert for auroras in the waxing twilight of northern Spring. Free: Aurora Alerts
First contact with the solar wind stream sparked a colorful display of auroras outside Fairbanks, Alaska:
“The colors were so beautiful, and it was amazing to watch the curtains wave and change from moment to moment,” reports photographer John Chumack. “Our crew enjoyed this dynamic display for many hours.”
TWINKLE, TWINKLE, CRESCENT VENUS: Like the Moon, Venus has phases, and right now it is a beautifully slender crescent. On March 17th, Italian astronomer Raffaello Lena used a small telescope to track Venus down to the horizon as it set in the evening sky of Rome. He recorded a beautiful example of atmospheric turbulence distorting the curved lines of the second planet:
This kind of scintillation is normally reserved for pinpoint objects like distant stars. Venus is so thin, it’s doing it too. In a related development, some observers have recorded the chromatic splitting of Venus into red, green, and blue crescents, making Venus look like a tiny rainbow in space.
All of this is happening because Venus is passing between Earth and the sun–an event astronomers call “inferior solar conjunction.” As Venus turns its night side to Earth, only a luminous sliver remains. Observers can find Venus shining through the twilight in the western sky at sunset. The crescent is easy to see in small telescopes and binoculars.
Above: “Rainbow Venus” photographed by Kevin R. Witman of Cochranville PA [more]
The Venus-sun distance will be least on March 25th. This is the most beautiful time to observe Venus, but also the most perilous. The glare of the nearby sun magnified by a telescope can damage the eyes of anyone looking through the eyepiece.
Anthony J. Cook of the Griffith Observatory has some advice for observers: “I have observed Venus at conjunction, but only from within the shadow of a building, or by adding a mask to the front end of the telescope to fully shadow the optics from direct sunlight. This is tricky with a refractor or a catadioptric, because the optics start at the front end of the tube. Here at Griffith Observatory, I rotate the telescope dome to make sure the lens of the telescope is shaded from direct sunlight, even through it means that the lens will be partially blocked when aimed at Venus. With our Newtonian telescope, I add a curved cardboard mask at the front end of the tube to shadow the primary mirror.”
THE FLIGHT OF THE EASTERNAUTS: The cosmic ray monitoring program ofEarth to Sky Calculus is not supported by government grants or big corporate sponsors. Instead we rely on you. That is, you and the Easternauts:
On March 2nd, the student researchers flew a payload-full of Easter bunnies to the edge of space–and you can have one for $39.95. (Space helmet included!) They make great Easter gifts for young scientists, and all proceeds support STEM education. Each bunny comes with a greeting card showing the Easternaut in flight and telling the story of its journey to the stratosphere and back again.
More far-out gifts may be found in the Earth to Sky store.
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 Mar. 21, 2017, the network reported 27 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 March 21, 2017 there were 1780 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: 21 Mar 17
The sun is blank–no sunspots. Credit: SDO/HMI
Sunspot number: 0
What is the sunspot number?
Updated 21 Mar 2017
Current Stretch: 15 days
2017 total: 27 days (34%)
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 21 Mar 2017
Current Auroral Oval:
Coronal Holes: 21 Mar 17
Solar wind flowing from the indicated coronal hole is buffeting Earth’s magnetic field on March 21st. 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 Mar 20 2200 UTC
Updated at: 2017 Mar 20 2200 UTC