Cold and Snow Pushing into South-Central U.S.; Fire Weather Concerns Persist in Northern California

An Arctic front will bring a wide swath of much below normal temperatures, snow, and chilly wind chills from the Rockies to the Mississippi Valley. Another cold front will bring more snow from the Great Lakes and Ohio Valley to the Northeast. Cold Arctic air in the Great Basin will continue to produce gusty winds and Critical Fire Weather threats to northern California. Read More >

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Astronomical Data and Information

The July setting sun casts its brilliance
over Lake of the Woods, Ontario

The principle of Rayleigh Scattering explains the red or orange sunsets. As the sun moves lower in the sky, its light has to travel through "more" of the atmosphere since the sun is at a much lower angle. In fact at the horizons on a level plane, the atmosphere is about 40 times more thick than it is directly overhead. Particles and molecules in the atmosphere will scatter out the shorter wavelengths (blue in the color spectrum) more easily than longer ones (red). Thus, we are left with the reddish portion of the light spectrum to see.

Season Starting Dates and Times
2018
Spring	Mar 20	11:15 AM CDT
Summer	Jun 21	5:07 AM CDT
Autumn	Sep 22	8:54 PM CDT
Winter	Dec 21	4:23 PM CST

2018 Major Meteor Showers
Shower	Peak Dates	ZHr*	Comments
Quadrantids	Jan 3-4	50-100	Peak time is in the evening of January 3rd to early morning January 4th. This meteor shower always favors northerly latitudes. This is because the radiant is near the handle of the Big Dipper in the northern night sky, however meteors with this shower can occur anywhere. The Quadrantids peak only lasts for a few hours and furthermore this year, a near full moon will provide major interference with this shower. Therefore observers will see only the brightest meteors with rates much less than 50-100 per hour.
Lyrids	Late evening Apr 22 to early morning Apr 23	10-20	Similar to the Quadrantids, the Lyrids' peak is somewhat brief. Look in the late evening of April 22nd to the early morning hours of April 23rd. However before midnight, a first quarter moon will interfere with the Lyrids, so best viewing will be after midnight. The radiant for this shower is near the border of the constellations Lyra and Hercules.
Eta Aquariids	May 6	10-20	Peak time occurs for a couple of hours just before sunrise on May 6th. A waning gibbous moon will provide quite a bit of interference as it will be in the same part of the sky as the radiant. This shower favors the southern hemisphere and the southern latitudes of the northern hemisphere as the radiant is from near the star Eta in the constellation Aquarius. In the northern U.S. and Canada, less than 10 to 20 meteors per hour can be expected whereas the shower is quite spectacular in the southern hemisphere. However with moon interference, only the brightest meteors will be seen this year.
Delta Aquariids	July 28-29	15-20	Peak time occurs from the late evening July 28th through the early morning of July 29th. Similar to the Eta Aquariids, this shower favors the southern hemisphere and the southern latitudes of the northern hemisphere as the radiant is near the star Delta in the constellation Aquarius. In the northern U.S. and Canada, less than 15 to 20 meteors per hour can be expected and the meteors are typically rather faint. Therefore light from a full moon this year will provide major interference.
Perseids	Aug 12-13	50-100	The peak of the Perseids will occur from the evening of August 12th when it gets dark, to the early morning hours of August 13th. Part of this year's peak time will occur at night for North America from late evening on the 12th, to 3 am CDT on the 13th. When coupled with a new moon, viewing the Perseids this year could be spectacular from a dark location. The radiant is in the constellation Perseus but meteors from the Perseids are seen all over the sky.
Orionids	Oct 21-22	10-20	Peak viewing will be on the evening of October 21st through the early morning hours of October 22nd. Unfortunately the peak will occur during the daylight on October 21st for North America, and a nearly full moon will provide major interference. Still, some of the Orionids are bright which should overcome the light from the near full moon. The radiant is north of Orion's red giant star, Betelguese, but the Orionids can occur anywhere in the sky.
Leonids	Nov 17-18	15	The peak this year will favor the evening hours of November 17th through the early morning of November 18th. A waxing gibbous moon will set shortly after midnight, therefore viewing after midnight on the 18th will be best. The radiant of the Leonids emanate from the constellation Leo.
Geminids	Dec 13-14	100-120	Peak viewing will be on the evening of December 13th into the morning hours of December 14th. A near first quarter moon will set close to 11 pm CST, therefore the best viewing will occur after 11 pm on December 13th with no moon interference. Although not as noteworthy as the Perseids, the Geminids are actually usually the best and most consistent shower each year. The problem is being winter in North America, many times the Geminids are obscured by clouds. The Geminids' radiant is near the twin's heads in Gemini, but will occur anywhere in the sky.

*ZHr is the maximum numbers of meteors expected per hour at Zenith (straight up in sky) and under a very dark sky. Average meteor rate can be expected to be less (much less in an urban environment.)

Radiant: A point in the sky in which meteors appear to originate.