Nightskies_apr_7

Jeff Green | Apr 07, 2005

Night Skies April 7, 2005

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by Leo Enright

The increase in hours of daylight is easily noticed as the month of April passes, and with the change to Daylight Saving Time on Sunday, April 3, that increase seems more dramatic than it actually is. At the beginning of April, sunset in this area is at about 7:30 p.m. EDT, and by the end of the month, it occurs a little after 8 p.m. EDT. This change of about 30 minutes in a 30-day month means that sunset is about one minute later each evening. The end of evening twilight changes by more than one minute per day, since it advances from 9:15 p.m. EDT at the first of the month to about 10 p.m. EDT at months end. In the mornings, sunrise times are earlier by an average of almost two minutes per day, moving from 6:50 a.m. at the first of the month to 6 a.m. on the last day of April.

During evening twilight, sky watchers can easily see the winter star patterns sinking low in the western sky and the large spring constellations moving up into the eastern and southern parts of the sky. High in the south, the outline of Leo, the Lion, is seen with its large backwards question mark forming the outline of the head and forepaws, with the brilliant star Regulus marking one front paw. Somewhat to his left and down into the southeastern sky stretches Virgo, the Maiden, marked by the very bright star Spica. Further to her left and down near the southeastern horizon is the box-like pattern of four stars known as Libra, the Scales. In the regions of these three large constellations, observers who have binoculars or a telescope can spend hours finding and studying many distant galaxies, and also many interesting variable stars within our own galaxy.

Of the five bright planets that so many people enjoy watching throughout the year, this month will give a good opportunity to see only three of them with the other two possibly seen be a few people, but there will be chances for excellent and memorable views of the three easily seen planets. Jupiter, the largest of all the planets, rises in the east at sunset, its brilliance dominating the eastern sky during the entire evening, and it finally sets in the west at sunrise. It is now closer to earth and appears larger in telescopes that at any other time this year, and anyone who has a telescope, large or small, or even a pair of binoculars should direct it toward Jupiter for the views of the darkish and lightish bands on its surface and the four bright moons that are always dancing around the planet and always seen in a different arrangement from night to night. Best binocular or telescopic views are to be obtained not right after sunset when the planet is low and in the atmospheric haze, but later in the evening when it is higher in the sky The planet Saturn, however, is one that is to be enjoyed both with the naked eye views and with a telescope right after sunset, or as soon as it can be seen, because, it is very high in the west in the constellation Gemini, as it has been for the past two years. During April, careful observers will notice that Saturn moves slowly eastward toward Geminis two brightest stars, Castor and Pollux, and if those observers have a small telescope, they may notice that the shadow of the planet actually falls across Saturns great ring system more clearly than it has in a long time. The third planet, reddish Mars, is to be seen rising in the southeastern sky, just over two hours before sunrise. Those who have star maps will notice that it has moved from the constellation Sagittarius into Capricornus. Observers with a telescope will also notice that in the second week of the month, Mars appears very close to a far more distant planet Neptune, one of the planets that can be seen only with binoculars or a telescope. Mars also brightens noticeably during the month of April, and this should remind us that later this year it will appear much brighter than usual and much larger in our telescopes, as it did in 2003, and also a reminder that it is only every second year that Mars puts on its show of brightness, and late 2005 will be one of those years. Mercurys chances of being seen are quite poor, because only those lucky enough to have clear skies very close to the horizon less than an hour before sunrise in the last week of the month are likely to see it for a few minutes before it disappears into the glow of the rising sun. Venus, too, will likely remain unseen until early May, though it is possible that a few fortunate people may spot it for several minutes above the northwestern horizon about 30 minutes after sunset in the last week of April.

The moon in its monthly orbit around the earth has several interesting conjunctions with planets this month. An hour before sunrise on the morning of April 3, the waning crescent moon presents an interesting sight just to the right of Mars, and the following morning it appears just below Mars. At the end of twilight on the evenings of April 14, 15, and 16, dont miss the views of the waxing crescent moon high in the western sky crossing the constellation Gemini near the planet Saturn and the bright stars Castor and Pollux. Also, at the end of twilight on the evening of April 21, there is the chance to see the gibbous moon above Jupiter in the constellation Virgo. At the same time the following evening, the moon is just below that planet, and the evening after that (April 23) the almost full moon is about the same distance below Spica, the brightest star in the constellation Virgo.

Three other events deserve an explanation. The annual Lyrid Meteor Shower occurs in April and reaches its maximum on April 21, 22, and 23, but unfortunately this year, many of the meteors from this shower will be difficult to see because of the bright moonlight on these nights just before the April Full Moon. Also, some people may hear of the semi-annual eclipse season bringing us two eclipses, a Solar Eclipse on April 8, and a Lunar Eclipse on April 24. The solar eclipse path is in the South Pacific Ocean, with some of the partial phase being visible in the southern U.S. It is NOT visible from any part of Ontario. As for the lunar eclipse, it is a penumbral lunar eclipse, with the moon not even touching the earths dark umbra, but only the nebulous penumbra or partial shadow, and so, locally it may be barely detectable in the short while before the moon sets very early on the morning of April 24. With the moon very low in the west at that time, the chances of noticing the slight darkening of the lunar disk are not very good. Observers in British Columbia and the Yukon will have the best chance of any Canadians of seeing this event with the moon high in the sky.

For the thirty-third year, Astronomy Day is being celebrated internationally on Saturday, April 16. The RASC is planning a day of activities, with displays and talks, to be held at Isabel Turner Library, near Kingstons Cataraqui Town Centre from 9 a.m. to 5 p.m. More information about all aspects of astronomy is to be found in the book, The Beginners Observing Guide, available from Sharbot Lake Pharmacy.

and the Pleiades star cluster, a very beautiful sight, but one that may require binoculars to see! The following night, May 10, at about the same time, the crescent will be slightly larger, but still a beautiful sight as it appears to the left of the bright start Capella. Two nights later still, on May 12, a larger crescent moon is to be seen just below the stars Castor and Pollux in Gemini, and on the 13th it is just to the left of these twin stars and just above the planet Saturn. On the nights of May 19 and 20, the gibbous moon is in the constellation Virgo, beside Jupiter on the 19th, and beside the star Spica on the 20th, an excellent demonstration of how far across the sky the moon travels in one day. During the night of the Full Moon, May 23 -24, the moon may be seen moving closer and closer to Antares, the brightest star in the constellation Scorpius, and in fact, covering the star, and hiding it for about an hour or more, in an event that is called an occultation. The disappearance of the star, as seen from this area should be at about 4:15 a.m. Once again I would be interested in hearing from anyone in the area who observes the event (whether using binoculars, a small telescope, or the unaided eye) and records precisely the time when the disappearance occurs. Another event well worth observing is the very close approach of Last Quarter Moon and the planet Mars during morning twilight on May 31.

The peak of the well-known Eta Aquarid Meteor Shower occurs between May 3 and 10 with the best chance of seeing bright and fast meteors in the southern sky early in the morning hours of May 5 and 6. If you observe for an hour or more on either or both of these mornings, be sure to record the number of meteors you see each hour.

More information about observing the moon, planets, and other objects of the spring and summer sky is to be found in the book The Beginners Observing Guide which is now available at Sharbot Lake Pharmacy.