Space Weather Update: 03/25/2017
By Spaceweather.com, 03/25/2017
POTENT CORONAL HOLE FACES EARTH: A canyon-shaped hole in the sun’s atmosphere is facing Earth, and it is spewing a stream of fast-moving solar wind toward our planet. NASA’s Solar Dynamics Observatory photographed the giant fissure on March 25th:
This is a “coronal hole” (CH) — a vast region where the sun’s magnetic field opens up and allows solar wind to escape. A gaseous stream flowing from this coronal hole is expected to reach our planet on during the late hours of March 27th and could spark moderately-strong G2-class geomagnetic storms around the poles on March 28th or 29th.
We’ve seen this coronal hole before. In early March, it lashed Earth’s magnetic field with a fast-moving stream that sparked several consecutive days of intense auroras around the poles. The coronal hole is potent because it is spewing solar wind threaded with “negative polarity” magnetic fields. Such fields do a good job connecting to Earth’s magnetosphere and energizing geomagnetic storms.
Arctic sky watchers should be alert for auroras early next week. Free: Aurora Alerts
INFERIOR CONJUNCTION OF VENUS: Today Venus is passing almost directly between Earth and the sun. With the planets so aligned, the night side of Venus is facing Earth and only a narrow sliver of Venus’ sunlit hemisphere is visible. This has turned the second planet into an exquisitely slender crescent:
Ofer Gabzo sends this picture from the Givatayim Observatory in Israel. “Venus was passing just 9° north of the sun, and had turned its lovely thin crescent exactly to the south,” says Gabzo. “Despite the angular proximity to the sun I did manage to get a glimpse of my favorite planet. The sun was obscured by the observatory’s dome to avoid risking the camera and the telescope’s optics.”
Astronomers call this an “inferior conjunction of Venus.” It is the most most beautiful time to observe Venus, but also the most perilous. Optics mis-pointed only slightly can catch the glare of the sun and focus its deadly rays onto vulnerable eyes. If you do try to observe Venus during inferior conjunction, take precautions like Gabzo did: Put the sun behind a tree or building and observe Venus from the safety of the shadows. Safer still is the Realtime Venus Photo Gallery.
FLYING TO THE AURORA AUSTRALIS: Last night, a group of sky watchers in Dunedin, New Zealand, boarded a plane and took off. They weren’t heading to another airport. Instead, they flew south into the aurora australis. Taichi Nakamura took these pictures from a window seat in Economy Class:
“I was grateful to be on board the first chartered flight to 66 degrees south last night from 45.9 degrees south Dunedin New Zealand,” says Nakamura. “Project name ‘Flight to the Light’ was a quest of aurora enthusiasts flying together to see the aurora more closely and was created by Dunedin’s Otago museum director Ian Griffin. During the flight, we were rewarded with magnificent views of the aurora australis completely surrounding us providing us a breathtaking observatory of the Southern Lights.”
A must-see video shows the lights in motion.
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. 25, 2017, the network reported 8 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 25, 2017 there were 1782 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: 25 Mar 17
Sunspot AR2643 poses no threat for strong solar flares. Credit: SDO/HMI
Sunspot number: 12
What is the sunspot number?
Updated 25 Mar 2017
Current Stretch: 0 days
2017 total: 27 days (32%)
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 25 Mar 2017
Current Auroral Oval:
Coronal Holes: 25 Mar 17
A fast-moving stream of solar wind flowing from the indicated coronal hole could reach Earth as early as March 27th (although the 28th is more likely). 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 24 2200 UTC
Updated at: 2017 Mar 24 2200 UTC