Space Weather Update: 03/18/2016
By Spaceweather.com, 03/18/2016
GREEN COMET APPROACHES EARTH: On March 21st, Comet 252P/LINEARwill make a close approach to Earth–only 0.036 AU (5.4 million km) away. This is the fifth closest cometary approach on record and, as a result, the normally dim comet has become an easy target for backyard telescopes. Indeed, it is brightening much faster than expected.
“Comet 252P/LINEAR has surpassed expectations and is now bordering on naked eye visibility for southern observers,” reports Michael Mattiazzo of Swan Hill, Australia. “At the moment it is near magnitude +6,” Observing from Brisbane, Australia, Tom Harradine didn’t even need a telescope to photograph 252P/LINEAR. On March 17th, he caught the green comet (circled) passing by the Tarantula Nebula using just a digital camera:
“This image is a stack of 140 four second exposures I made using a Canon EOS 70D set at f/4.0, ISO 12800, and 200mm,” he says.
The comet is green because its vaporizing nucleus emits diatomic carbon, C2, a gas which glows green in the near-vacuum of space. The verdant color will become more intense in the nights ahead as 252P/LINEAR approaches Earth.
In recent days, astronomers have realized that Comet 252P/LINEAR might have a companion. A smaller and much dimmer comet named “P/2016 BA14” will buzz Earth even closer than 252P/LINEAR on March 22nd. P/2016 BA14 appears to be a fragment of 252P/LINEAR. Unlike its parent, however, P/2016 BA14 is “pitifully faint” and difficult to observe. Sky and Telescope has the full story.
There is a chance that the comet’s approach could cause a minor meteor shower. According to the International Meteor Organization, “[modeling by forecaster] Mikhail Maslov indicates that there might be a weak episode of faint, very slow meteors (15.5 km/s) on March 28–30 from a radiant near the star μ Leporis.” Little is known about meteors from this comet, so estimates of the meteor rate are very uncertain. Maslov’s models suggest no more than 5 to 10 per hour.
This is a southern hemisphere event. At closest approach on March 21st, 252P/LINEAR will speed through the constellations Triangulum Australis and Apus, far south of the celestial equator. Observers can use this ephemeris to point their cameras and telescopes.
SOLAR WIND SPARKS AURORAS: For the past three days, a stream of solar wind has been buffeting Earth’s magnetic field, causing intermittent G1-classgeomagnetic storms around the Arctic Circle. On March 15th, Didier Van Hellemont of Luosto, Finland, looked up at just the right moment and saw this:
This is called a “corona”–a spray of colorful lights seen by observers who look straight up into the folds of auroral curtains. “There were no less than 6 corona events that night!” says Van Hellemont. “This spectacular specimen showed a lot of movement. It was fantastic.”
The stream of solar wind which caused the display has been especially effective at sparking auroras. The reason: Magnetic fields inside the stream have a negative polarity. This means they can link to Earth’s magnetic field, opening a crack in our planet’s magnetosphere and allowing solar wind inside. Auroras inevitably follow.
A SPHERICAL VIEW OF THE SOLAR ECLIPSE: Eight days ago, the students ofEarth to Sky Calculus stood on a beach in Indonesia waiting for the cool shadow of the Moon to sweep over the white sands of Belitung Island. They were there to test cameras for high-altitude ballooning–specifically, the Solar Eclipse Balloon Network. One of those cameras had a spherical lens, able to see in all directions at once. Here is how it viewed the students setting up their experiment on the beach:
We already know that this camera, a Ricoh Theta S, can operate at the edge of space. It traveled there in late February and took spectacular pictures of the stratosphere. But could it photograph a total eclipse of the sun? The answer is “yes.”
Minutes after the first picture was taken, the shadow of the Moon engulfed Belitung Island, and the Ricoh did a great job capturing the alien twilight. Click here to transport yourself to the path of totality.
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. 17, 2016, the network reported 12 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 18, 2016 there were 1689 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: 427.3 km/sec
density: 2.3 protons/cm3
explanation | more data
Updated: Today at 1415 UTX-ray Solar Flares
6-hr max: B2 0710 UT Mar18
24-hr: B5 0017 UT Mar18
explanation | more data
Updated: Today at: 1400 UTDaily Sun: 18 Mar 16Not one of these sunspots has the type of unstable magnetic field that poses a threat for strong flares. Solar activity remains low. Credit: SDO/HMI
Sunspot number: 66
What is the sunspot number?
Updated 18 Mar 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 18 Mar 2016
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/OvationPlanetary K-index
Now: Kp= 2 quiet
24-hr max: Kp= 3 quiet
explanation | more data
Interplanetary Mag. Field
Btotal: 6.0 nT
Bz: 1.7 nT south
explanation | more data
Updated: Today at 1415 UTCoronal Holes: 18 Mar 16
Earth is inside a stream of solar wind flowing from the indicated coronal hole. Credit: SDO/AIA.Noctilucent Clouds The southern season for noctilucent clouds began on Dec. 13, 2015. It is expected to end in late February or March 2016.
Switch view: Ross Ice Shelf, Antarctic Peninsula, East Antarctica, PolarUpdated at: 02-12-2016 16:55:02
Updated at: 2016 Mar 17 2200 UTC
Probabilities for significant disturbances in Earth’s magnetic field are given for three activity levels: active, minor storm, severe stormUpdated at: 2016 Mar 17 2200 UTCMid-latitudes