You are viewing the page for Sep. 19, 2009
  Select another date:
<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
Current conditions
Solar wind
speed: 340.7 km/sec
density: 0.5 protons/cm3
explanation | more data
Updated: Today at 2345 UT
X-ray Solar Flares
6-hr max: A2
1930 UT Sep19
24-hr: A2
1930 UT Sep19
explanation | more data
Updated: Today at: 2340 UT
Daily Sun: 18 Sept. 09
The Earth-facing side of the sun is blank--no sunspots.. Photo credit: SOHO/MDI
Sunspot number: 0
What is the sunspot number?
Updated 18 Sept 2009

Spotless Days
Current Stretch: 17 days
2009 total: 210 days (81%)
Since 2004: 721 days
Typical Solar Min: 485 days
explanation | more info
Updated 18 Sept 2009

Far side of the Sun:
This holographic image reveals an active region on the far side of the sun. It is located at latitude 30-deg south, making it a probable member of Solar Cycle 24. Image credit: Global Oscillation Network Group
Planetary K-index
Now: Kp= 0 quiet
24-hr max: Kp= 1
explanation | more data
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Interplanetary Mag. Field
Btotal: 3.6 nT
Bz: 0.0 nT
explanation | more data
Updated: Today at 2345 UT
Coronal Holes:
There are no coronal holes on the Earth-facing side of the sun. Credit: SOHO Extreme UV Telescope
NOAA Forecasts
Updated at: 2009 Sep 19 2201 UTC
0-24 hr
24-48 hr
01 %
01 %
01 %
01 %
Geomagnetic Storms:
Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2009 Sep 19 2201 UTC
0-24 hr
24-48 hr
05 %
05 %
01 %
01 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
05 %
05 %
01 %
01 %
01 %
01 %
What's up in Space
September 19, 2009

AURORA ALERT: Did you miss the Northern Lights? Next time get a wake-up call: Spaceweather PHONE.


VENUS HAS A SIDEKICK: Look east just before dawn on Sunday morning, Sept. 20th. There's Venus, as usual, shining through the rosy glow of sunrise. A pair of binoculars trained on Venus reveals a temporary sidekick: 1st-magnitude star Regulus less than 0.5o away. Don't miss it: sky map.

APPROACHING SUNSPOT: NASA's STEREO-B spacecraft stationed over the sun's eastern limb is monitoring an active region not yet visible from Earth. STEREO's extreme ultraviolet telescope captured this image on Sept. 19th:

The tangle of hot, magnetized plasma circled above almost certainly overlies a large new-cycle sunspot. We'll soon find out. The sun's rotation is turning the active region toward Earth and it could pop over the sun's eastern limb as early as Sept. 21st. Readers with solar telescopes are encouraged to monitor developments.

FOGBOW SEASON: Northern autumn is beginning and that means it's fogbow season. The weeks of late September and early October often bring banks of fog to the countryside, where moist ground has spent the night cooling under a cloudless, starry sky. When the sun comes up, warms the ground, and sunlight hits the rising mist--voila!--a fogbow:

Claude Duplessis took the picture at daybreak on Sept. 17th. "I spent the night in La Vérendrye Wildlife Reserve in Québec," he says. "In the morning, as I prepared to leave, this white 'bow popped out of the mist."

Fogbows are close cousins of rainbows. The difference is droplet size. Rainbows appear when sunlight bounces in and out of large raindrops. The same type of reflection produces a fogbow, except fog droplets are much smaller. Small droplets don't separate the colors of sunlight as widely as large raindrops do. In a fogbow, therefore, the colors are smeared together, producing a ghostly-white arc.

To see a fogbow on a misty autumn morning, face away from the rising sun and look into the fog. The lower the sun, the higher the arc, so wake up early for best results!

more images: from Daryl Pederson of Prince William Sound, Alaska; from Tyler Burg of Pisgah, Iowa; from Ákos Ujj of Bátonyterenye, Hungary;

Sept. 2009 Aurora Gallery
[previous Septembers: 2008, 2007, 2006, 2005, 2004, 2002, 2001]

Explore the Sunspot Cycle

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 September 19, 2009 there were 1073 potentially hazardous asteroids.
Sept. 2009 Earth-asteroid encounters:
Miss Distance
2009 QC35
Sept. 2
2.9 LD
35 m
2009 RY3
Sept. 11
1.9 LD
50 m
2009 RR
Sept. 16
2.8 LD
33 m
2009 RG2
Sept. 21
9.1 LD
31 m
2009 HD21
Sept. 29
22.9 LD
1.0 km
1998 FW4
Sept. 29
8.6 LD
550 m
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.
Essential Links
NOAA Space Weather Prediction Center
  The official U.S. government space weather bureau
Atmospheric Optics
  The first place to look for information about sundogs, pillars, rainbows and related phenomena.
Solar and Heliospheric Observatory
  Realtime and archival images of the Sun from SOHO.
  3D views of the sun from NASA's Solar and Terrestrial Relations Observatory
Daily Sunspot Summaries
  from the NOAA Space Environment Center
Current Solar Images
  from the National Solar Data Analysis Center
Science Central
  more links...
©2008, -- This site is penned daily by Dr. Tony Phillips.
©2019 All rights reserved.