By Spaceweather.com, 02/25/2017
ANNULAR SOLAR ECLIPSE: On Sunday, Feb. 26th, the Moon will pass in front of the southern hemisphere sun, covering as much as 99% of the solar disk. Astronomers call this an “annular” solar eclipse. Observers in parts of South America and Africa will be able to witness a magnificent “ring of fire” in the sky as crescent-shaped sunbeams dance on the ground below. Watch this cool animation from ShadowandSubstance.com.
SOLAR WIND SPARKS AURORAS: Earth is moving deeper into a solar wind streamflowing from a hole in the sun’s atmosphere. With wind speeds topping 600 km/s, the stream is buffeting our planet’s magnetic field and sparking bright auroras round the Arctic Circle. Frank Olsen sends this picture from Morfjord at Lofoten, Norway:
NOAA forecasters say there is a 40% chance that G1-class magnetic storms will occur on Feb. 25th. That means the next photos could be even better. Monitor the realtime aurora gallery for sightings. Free: Aurora Alerts
POLLEN CORONAS: In parts of New Mexico, people are starting to sneeze–and see colorful rings around the sun. The two experiences are related. They are both manifestations of pollen. Photographer Harald Edens of Magdalena NM explains: “Every year in late February or early March, the juniper trees in New Mexico produce pollen. The pollen particles are all quite small and uniform in size; as a result, they scatter sunlight and produce colored rings around the sun.”
“Today’s pollen corona was by far the most intense I have observed in New Mexico over the past 14 years, with up to four orders (repeated color bands) readily visible to the unaided eye,” Edens continues. “The pollen is so abundant that it appears like smoke coming off the juniper trees whenever there is a gust of wind, or a bird lands in a tree.”
Readers, if you see a pollen corona, here’s something else to look for: The colorful rings are not always circular. Pollens are non-spherical; many have air sacs to help carry them in the wind. These align the grains to give beautiful elliptical coronas with bright spots.
AURORA ROCKET LAUNCH: On Feb. 22nd, shortly after midnight, bright green auroras erupted over Alaska’s Poker Flat Research Range. Researchers from Dartmouth College promptly launched a rocket into the glowing maelstrom. Photographer Marketa Murray of Fairbanks captured the event in a perfectly-timed self-portrait:
“We tuned into the Poker Flat Research Range radio for a heads-up that the rocket was about to launch,” explains Murray. “The picture shows both stages of the Black Brant IX sounding rocket burning for the ionosphere.”
The goal of the mission, named ISINGLASS (Ionospheric Structuring: In Situ and Groundbased Low Altitude Studies) is to decipher the mysterious shapes of the aurora borealis. Some auroras look like flames, others like swirls, ripples or curtains. The rocket was designed to scatter an array of sensors into the auroral zone, mapping the particles and fields underlying these forms.
“Auroras are the last step of a chain of processes connecting the solar wind to the atmosphere,” says Dr. Kristina Lynch of Dartmouth, the mission’s principal investigator. “We are seeking to understand what structure in these visible signatures can tell us about the electrodynamics of processes higher up.”
“It was a beautiful launch with an extensive set of collaborative ground based data, and will make a great study,” she says.
Ultimately, the results could allow researchers to look up at the sky and, based on little more than the shapes they see, predict conditions at the edge of space. Was the mission a success? Stay tuned for updates from the launch team.
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. 25, 2017, the network reported 80 fireballs.
(79 sporadics, 1)
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 25, 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: 25 Feb 17
The magnetic field of sunspot AR2638 is decaying, and it no longer harbors energy for M-class solar flares. Credit: SDO/HMI
Sunspot number: 27
What is the sunspot number?
Updated 25 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 25 Feb 2017
Current Auroral Oval:
Coronal Holes: 25 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 24 2200 UTC
Updated at: 2017 Feb 24 2200 UTC