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  Night Sky

Night Sky

.Enjoy our starry night skies
Be a considerate neighbor: reduce nighttime glare.
Shield your outside lights downward.
Let the stars light up the night.

April 2012 Night Sky

Charlie Christmann

Evening Spectacle

In case you haven’t noticed, the western sky in the evening holds quite a sight: two very bright planets side-by-side. The middle of March was the best time to see the pair snuggling up close, and throughout April, Jupiter dives toward the horizon ahead of Venus.

After enjoying those planets, look overhead, in Leo, for bright, rusty Mars next to Regulus. Mars is just past opposition. Every 26 months, Mars and Earth form a straight line from the sun. This is “opposition,” the point where Mars is opposite the sun in the sky. This is also the time when the distance between Earth and Mars is at a minimum. You may hear, almost every cycle, how Mars will be bigger and brighter than the Moon. Well, look close, because this is about as big and bright as Mars will get this year.

Mars is also in retrograde at this time. Instead of progressing from east to west through the Zodiac, retrograde planets appear to temporarily move backward in the sky. Retrograde motion will continue through the middle of June.

Now look above the eastern horizon for Saturn to the right of the bright star Spica in the constellation Virgo.

Active Sun

It seemed like Solar Cycle 24 would never come. This is the 24th eleven-year cycle of the sun that has been observed. Each cycle starts and ends with the sun quiet, showing few sun spots. In the middle, activity peaks and erupts with numerous sunspots and large flares.

The last cycle, number 23, ended in 2009, when the sun went spotless for 260 days. Since then, the sun spot activity has ramped up slowly. However, spot number AR1429 is extremely active, spewing the largest solar eruptions of the cycle. Starting 29th, several large explosions rocked the far side of the sun ejecting solar material into space.

There are three categories of solar flares: X, M, and C. X-class are the big ones, triggering planet-wide radio blackouts and long-lasting radiation storms. M-class are mid-sized ones causing brief radio blackouts that affect Earth’s Polar Regions. And, C-class flares are hardly noticeable. The largest known flare occurred on September 1, 1859, producing auroras at tropical latitudes such as Cuba or Hawaii, and set telegraph systems on fire. It also left a chemical signature in the Greenland glaciers. In modern times, the largest flare was on November 4, 2003, blinding the GOES satellite solar detectors. The estimated rating was X45 and had auroras visible in New Mexico. Many strong M-class and X-class flares are associated with coronal mass ejections (CME).

March 2nd, is the day AR1429 debuted on the edge of the earth-facing sun face with an M-3 class flare. This sun spot has been extremely active:

Flare Date/Flare class

March 2 / M-3
March 3 / M-2
March 4 / X-1
March 7 / X-5 with Earth-directed CME
March 8 / M-6 with Earth-directed CME
March 10 / M-8 almost an X-class
March 13 / M-7

As of March 14th, busy spot AR1429 has traveled across the face of the sun and is now disappearing from sight. Auroras have been observed for a full week near the Arctic Circle and some as far south as the Canadian-US border.

Along with the M and X flares, satellites and astronauts in orbit can experience higher radiation levels and must take precautions. For X-class flares, airlines will sometimes reroute polar traversing flights to avoid elevated radiation.

Though this solar cycle is forecast to be less active than the previous, with fewer flare producing spots, higher levels of activity are expected as this cycle peaks sometime in 2013.

The Planets and Moon

  • Venus and the Pleiades cluster will be in conjunction on the 3rd. Look on the 24th to see bright Venus to the upper right of the waxing crescent Moon after sunset.
  • On April 1st—Mars will be as big and as bright at the full moon. Look for Mars to the left of Regulus in a conjunction on the 15th.
  • Saturn reaches opposition on the 15th.
  • The Moon is full at 1:19 p.m. on the 6th, which is also Good Friday. Also look for Spica, 2 hours after sunset, to the left of the full Moon. The Moon is new at 1:18 a.m. on the 21st.
  • Easter is on the 8th. Enjoy Astronomy Day on the 28th.
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