By Spaceweather.com, 02/11/2017
DISAPPOINTING COMET FLYBY: This weekend, Comet 45P/Honda-Mrkos-Pajdusakova is flying past Earth only 7.4 million miles away–the 8th-closest comet flyby of the Space Age. Unfortunately, the comet is invisible to the naked eye and even observers with telescopes are having trouble seeing it. After losing many of its volatile gases when it flew past the sun in December, the depleted comet is much dimmer than forecasters expected: photo gallery. Sky maps: Feb. 11, 12.
SNOW MOON PASSES THROUGH EARTH’S SHADOW: According to folklore, this weekend’s full Moon is called the “Snow Moon.” For northerners, it often feels like the brightest Moon of the year as moonlight glistens off the white February landscape. For a while on Friday night, the Snow Moon lost some of its luster when it passed, off center, through the shadow of our planet. Tom Bailey photographed the event from Urbandale, Iowa:
Note the darkening in the upper left quadrant of the lunar disk. That’s our planet’s shadow. When the Moon skims the edge of Earth’s shadow as it did on Friday night, astronomers call it a “penumbral lunar eclipse.” In this case, it was a double eclipse: “As I was shooting the eclipse, a jet passed between my location and the Moon,” says Bailey.
Observers on every continent except Australia witnessed the shadow. Browse the gallery for more sightings.
FUNNEL CLOUD: Note to photographers: When you see a funnel cloud reaching down out of a stormy sky, the correct response is usually Run! Brazilian photographer Helio C. Vital made a different choice. Click! He snapped this picture on Feb. 7th from Rio de Janeiro:
“The cloud appeared about a half hour before sunset,” says Vital. “It was part of a thunderstorm cell that was approaching, announcing the arrival of a new weather system that would bring rain to the city several hours later.”
Meteorologists call this type of cloud a “tuba” — a swirling mass of moist air that can hang down from an active thunderstorm. A tuba that touches the ground gets a new name: tornado. “Fortunately, in spite of its threatening appearance, this tuba did not reach the ground and no damage was reported,” says Vital.
Click! was the correct choice after all.
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. 11, 2017, 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 February 11, 2017 there were 1773 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: 11 Feb 17
AR2635 poses no threat for strong solar flares. Credit: SDO/HMI
Sunspot number: 18
What is the sunspot number?
Updated 11 Feb 2017
Current Stretch: 0 days
2017 total: 11 days (25%)
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 11 Feb 2017
Current Auroral Oval:
Coronal Holes: 11 Feb 17
A stream of solar wind flowing from the indicated coronal hole will probably sail northof Earth this weekend, having little effect on our planet’s magnetic field. 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: 02-11-2017 16:55:03
Updated at: 2017 Feb 10 2200 UTC
Updated at: 2017 Feb 10 2200 UTC