Space Weather Update: 05/26/2016
By Spaceweather.com, 05/26/2016
CHANCE OF MINOR STORMS: NOAA forecasters estimate a 40% chance of minor G1-class geomagnetic storms on May 27th when Earth enters a high-speed stream of solar wind. High-latitude sky watchers should be alert for auroras, especially in the southern hemisphere where darkening autumn skies favor visibility of faint lights. Aurora alerts: text, voice.
SPRITES (AND SOMETHING MORE) OVER OKLAHOMA: On May 23rd, an enormous swarm of sprites flickered and danced across the top of a thunderstorm in Oklahoma. Almost 400 miles away in New Mexico, amateur astronomer Thomas Ashcraft trained his cameras on the display. He captured the sprites–and something more:
“Note the dendritic upward spray in the midst of the sprite cluster,” points out Ashcraft. “That is a possible ‘pop-through gigantic jet’–a rare event.”
Ashcraft has posted a video of the event with VLF-ELF radio emissions he recorded as a soundtrack. Turn up the volume: “The deep bass sound of the lightning stroke sounds like a distant shotgun blast in the night,” he says.
What is a pop-through gigantic jet? Lightning scientist Oscar van der Velde of the Technical University of Catalonia explains: “A cluster of sprites can actually warp Earth’s ionosphere, bringing it down from its usual altitude of 90 km to only 40 km.” This sets the stage for the jet.
“The sprite cluster triggers an upward-directed discharge which in the past received fancy names as ‘troll’ or ‘palm tree’,” says van der Velde. “A satellite-based study by Taiwanese researchers in 2012 found them similar to gigantic jets–large isolated discharges reaching from the thundercloud toward the ionosphere. In case of a ‘pop-through gigantic jet,’ the lowering of the ionosphere is not uniform and the jet may then reach higher than the bottom tendrils of the sprite.”
Although sprites have been seen for at least a century, most scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now “sprite chasers” routinely photograph sprites–and more!–from their own homes. “They are easily detected by certain cameras,” says van der Velde, “and if a storm is in the mood, you may record one every few minutes.” Give it a try!
FEAR AND DREAD AROUND MARS: The moons of Mars are so small, some astronomers believe they are captured asteroids. Named Phobos and Deimos (Fear and Dread), the diminutive satellites average 17 km in diameter and are rarely seen in pictures of the Red Planet. On May 24th, astrophotographer Dennis Simmons of Brisbane, Australia, attempted to capture both. Rate of success: 100%.
Mars shines 242,000 times brighter than Phobos and 741,000 times brighter than Deimos. The two moons are easily lost in the glare. “Deimos was relatively easy, but Phobos had to be gently teased out of the data,” says Simmons, who used a 9 inch Celestron telescope.
This is a good time for astrophotographers to seek Fear and Dread. Why? Because Mars is unusually close to Earth. On May 30th, the two planets will be only 47 million miles apart–the closest they’ve been since 2005. This proximity not only boosts the apparent brightness of the tiny moons, but also increases their angular separation from Mars. Browse the gallery for sightings.
WAITING FOR NOCTILUCENT CLOUDS: Every year in late May, noctilucent clouds (NLCs) gather over Earth’s north pole where they remain, rippling hypnotically, until the end of Arctic summer. NLCs are, by far, Earth’s highest clouds. Seeded by meteoroids, they float in a thin layer ~83 km above the planet’s surface. With the beginning of the season upon us, NASA’s AIM spacecraft is monitoring the Arctic for signs of electric blue:
This is called a “daily daisy.” It assembles scans from AIM’s Cloud Imaging and Particle Size (CIPS) instrument into an ensemble picture of the Arctic. Noctilucent clouds would appear as wispy filaments criss-crossing the Arctic Circle. You can see the daily daisy updated every 24 hours right here on Spaceweather.com.
So far AIM’s daily daisy is empty–no NLCs. There has been one ground-based sighting that suggests the season might already be underway. We will know for sure when AIM spots the first Arctic NLCs of 2016 from space.
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 May. 26, 2016, the network reported 7 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 May 26, 2016 there were 1701 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:Asteroid
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
Situation Report — Oct. 30, 2015Stratospheric Radiation (+37o N)
Cosmic ray levels are elevated(+6.1% above the Space Age median). The trend is flat. Cosmic ray levels have increased +0% in the past month.
Sept. 06: 4.14 uSv/hr (414 uRad/hr)
Sept. 12: 4.09 uSv/hr (409 uRad/hr)
Sept. 23: 4.12 uSv/hr (412 uRad/hr)
Sept. 25: 4.16 uSv/hr (416 uRad/hr)
Sept. 27: 4.13 uSv/hr (413 uRad/hr)
Oct. 11: 4.02 uSv/hr (402 uRad/hr)
Oct. 22: 4.11 uSv/hr (411 uRad/hr)
These measurements are based on regular space weather balloon flights: learn more.
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. Our measurements show that someone flying back and forth across the continental USA, just once, can absorb as much ionizing radiation as 2 to 5 dental X-rays. For example, here is the data from a flight on Oct. 22, 2015:
Radiation levels peak at the entrance to the stratosphere in a broad region called the “Pfotzer Maximum.” This peak is named after physicist George Pfotzer who discovered it using balloons and Geiger tubes in the 1930s. Radiation levels there are more than 80x sea level.
Note that the bottom of the Pfotzer Maximim is near 55,000 ft. This means that some high-flying aircraft are not far from the zone of maximum radiation. Indeed, according to the Oct 22th measurements, a plane flying at 45,000 feet is exposed to 2.79 uSv/hr. At that rate, a passenger would absorb about one dental X-ray’s worth of radiation in about 5 hours.
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.
speed: 359.8 km/sec
density: 12.2 protons/cm3
explanation | more data
Updated: Today at 1751 UTX-ray Solar Flares
6-hr max: C1 1337 UT May26
24-hr: C1 1337 UT May26
explanation | more data
Updated: Today at: 1700 UTDaily Sun: 26 May 16Departing sunspot AR2546 is crackling with minor C-class solar flares. Credit: SDO/HMI
Sunspot number: 27
What is the sunspot number?
Updated 26 May 2016
Current Stretch: 0 days
2016 total: 0 days (0%)
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 26 May 2016
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/OvationPlanetary K-index
Now: Kp= 1 quiet
24-hr max: Kp= 1 quiet
explanation | more data
Interplanetary Mag. Field
Btotal: 3.8 nT
Bz: 1.4 nT south
explanation | more data
Updated: Today at 1748 UTCoronal Holes: 26 May 16Solar wind flowing from the indicated coronal hole could reach Earth on May 26-27. Credit: SDO/AIA.Noctilucent Clouds Images from NASA’s AIM spacecraft are once again appearing on Spaceweather.com. Check back daily for space-based sightings of noctilucent clouds.
Switch view: Europe, USA, Asia, PolarUpdated at: 05-26-2016 03:55:03
Updated at: 2016 May 25 2200 UTC
Probabilities for significant disturbances in Earth’s magnetic field are given for three activity levels: active, minor storm, severe stormUpdated at: 2016 May 25 2200 UTCMid-latitudes