Skywatching April 2013



Image Source

Daylight continues to increase throughout April.  Nearly 80 minutes of daylight are added during the month as the sun rises north of east, rises higher in the south and sets north of west this month.

Moon Phases

Moon Phase Date Moonrise Moonset
Last Quarter April 2 1:39 a.m. 12:33 p.m.
New Moon April 10 5:59 a.m. 8:49 p.m.
First Quarter April 18 12:16 p.m. 2:25 a.m. (4/19)
Full Moon April 25 7:56 p.m. 6:20 a.m. (4/26)

Data from US Naval Observatory

The Evening Sky

Jupiter continues to dominate the sky throughout the month.  On April 1, this giant planet is about halfway up in the western sky at sunset.  It appears lower in the west each week at the same time.

jup_moon-0414

On April 14, the waxing crescent moon appears about 4 degrees to the left of Jupiter.  The chart above shows the grouping at 8:30 p.m. CDT.  The moon and Jupiter appear in front of the stars of Taurus with its bright star Aldebaran and prominent Pleiades star cluster.

Saturn rises into the eastern sky shortly after sunset this month.

sat_opposition

On April 28, Earth moves between Saturn and the sun as shown in the diagram above.  (Click the chart to see it larger.)  At this time, Saturn is visible in the sky all night and it is closest to Earth as it gets.  At opposition, Saturn rises in the southeast at sunset.  During the evening hours it rises higher into the sky, appearing south at midnight.  During the early morning hours, it moves westward appearing lower in the southwest as it sets at sunrise.

moon_sat.jpg

A few days before opposition, the moon appears near Saturn.  The chart above shows the moon’s eastward movement at 10 p.m.  CDT each evening.  On April 24, the bright nearly full moon is to the lower left of Spica.  The next night the moon appears below Saturn.

Venus begins rapid movement into the evening sky after is March superior conjunction.  By month’s end, it is about 9 degrees to the east of the sun and difficult to see. Early next month, it appears in the evening sky near the the waxing crescent moon.  For more about Venus as an Evening Star, see our detailed posting here.

Mars is not visible this month.  On April 18, the Red Planet is behind the sun at conjunction.  It will return to the morning sky during early summer, appearing near Jupiter in the morning of July 22.

Presentation1

This chart shows the relative positions of Earth, Sun, and Mars on April 18 when Mars is at conjunction.  (Click the image to see it larger.)

Morning Sky

Mercury  lingers in the April predawn sky early in the month, although it rises in mid-twilight.

merc_lune

On the morning of April 8, the waning crescent moon appears near Mercury.  The chart above shows the pair at 6 a.m. CDT, less then 30 minutes before sunrise.  Find a clear eastern horizon.  Locate the moon with binoculars and then look for Mercury  about 7 degrees to the lower right.  With 7×50 binoculars, the celestial pair may just fit into the binocular field.  Hold the binoculars so that the moon is in the upper left of the field and Mercury may appear to the lower right of the field.  Depending on the binocular, Mercury may appear just outside the view with the moon, so  move the binocular slightly so the moon leaves the field and Mercury enters the view.

By month’s end, the planet is lost in the sun’s glare.

sol_sys_0412

As viewed from above the chart shows the positions of the visible planets on April 15, 2013.   (Click the image to see it larger.) The sun is between Venus and Mars, making them difficult to observe.  Jupiter is on the evening side of Earth, while Saturn is near opposition as explained above.  Mercury is on the morning side of the sky, but difficult to observe.

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