Sky events for April 2013
May 1 – Sunrise at 5:48 a.m., sunset at 8:03 p.m.
May 1 – Last Quarter Moon (overhead at sunrise).
May 5/6 – Eta Aquarid meteor shower (*moonless*).
May 9 – New moon (rises/sets with the sun).
May 9 – Annular solar eclipse in Australia.
May 11 – Mercury is directly behind the sun.
May 13 – The moon is at apogee (252,168 miles).
May 18 – First quarter moon (overhead at sunset).
May 25 – Full moon (moon rises/sets as sun sets/rises).
May 25 – The moon is at perigee (222,685 miles).
May 31 – Last quarter moon (sets at midday).
May 31 – Sunrise at 5:17 a.m., sunset at 8:35 p.m.
Eta Aquarid meteor shower
On the night of May 5, Halley’s Comet will still be in the outer solar system, but good old Mother Earth will clean up the mess it left behind and turn them into fireworks in Portage County’s night sky.
Anytime after midnight the dust particles hit our side of Mother Earth in the face but at about 3 a.m., May 6, she gets it right between the eyes at a rate of about one per minute.
Bright planets meet at dusk
As Jupiter falls, Venus and Mercury rise, until on May 26 the three planets will unite in the twilight within two degrees of one another. Venus will be the brightest (MAG. -3.9) followed by Jupiter (MAG. -1.9) to its upper left and finally Mercury (MAG. -0.9) at the apex (to the upper right of Venus) of the three.
May finds Mars hiding behind the sun but Earth is between Saturn and the sun, making Saturn visible most of the night, all month. You can locate Saturn by finding the handle of the Big Dipper and following the arc of the handle away from the bowl of the dipper to the bright star Arcturus, and then continue curving to the bright star Spica.
However, if you don’t curve as much to Spica, you’ll hit Saturn instead.
Comet remains a treat
With just binoculars Comet PANSTARRS is easy to find and is visible all May, all night! To find the comet you’ll have to practice finding the constellation Cepheus. Cepheus is house shaped (square base, with a triangle roof).
The easiest way to locate the comet is to locate the pointer stars (the two stars at the front of the bowl of the Big Dipper) and follow the pointer stars higher in the sky to Polaris (the North Star at the end of the handle of the Little Dipper) and just continue onto the next star Alrai (gamma Cepheus).
Alrai is located at the top of the house shaped constellation. The comet will be in the lower left of Alrai early May, at Alrai mid-May, and to the upper right of Alrai at month’s end.
How many stars can you see?
The following table shows the number of stars, visible from Earth, at the following magnitude ranges.
Number of Stars Magnitude Range
2 (brightest) -1.5 to -0.51
6 -0.5 to 0.49
14 0.5 to 1.49
71 1.5 to 2.49
190 2.5 to 3.49
610 3.5 to 4.49
1,929 4.5 to 5.49
5,946 5.5 to 6.49
So with a moonless sky, no auroras, no comets, after astronomical sunset, no human light pollution, with no optical aid, a person with 20/20 vision can distinguish 8,768 stars throughout the 24-hour rotational period of the Earth from the equator.
At Portage County latitudes we see about one-fourth of the stars year round, one-half the stars seasonally, and never see one fourth of the stars. Thus, from the darkest spot in Portage County on the first day of winter (longest night), around 1,170 stars can be seen from sunset to sunrise with no optical aid, over 100,000 stars with binoculars.
Incandescent, fluorescent, LED
Producers have stopped making all the incandescent light bulbs to meet federal energy standards by 2014. Fluorescent light bulbs contain the hazardous element mercury. The benefits of LED (Light Emitting Diode) lights include energy savings (over $100 per bulb), long life (decades), instant-on, quiet (no-hum), will not fade fabrics, and mercury-free.
To see comparisons between light bulbs go to www.designrecycleinc.com/led comp chart.html This will be the first generation of people that take their light bulbs with them when they move.
Responsible lighting lights only the area intended (not the sky) using reflecting hoods to direct where the light is needed and just uses the brightness necessary. An 800 lumen bulb, one meter (3.28 feet) away, gives 64 lux of light but one-half of a meter (1.64 feet) away gives 256 lux. 50 lux is plenty to see, and 100 lux is plenty to read. GNATS
Editor’s note: Paul Konichek teaches math, astronomy and physics at SPASH. GNATS is the acronym for “go now and teach someone.”