Night Lights: Constellations march toward spring

By Andy Veh, Redoubt Reporter

An interesting constellation in March is Leo, its shape quite closely resembling that of a male lion, looking west, in the direction that it will move during the next couple of months. Its right front paw is the bright star Regulus.

While Leo should move across the sky as gingerly as any constellation week after week, it seems to be much speedier than others. What aids or produces that perception is that sunset occurs later and later, about 20 minutes each week. Thus, with it getting darker later every evening, it seems that Leo keeps progressing faster across the sky (because we look at it later when it already has moved farther west).

As a result, I perceive Leo as the harbinger of spring. When it appears in the east, winter’s end will soon be here and when it reaches the western horizon, flowers are in full bloom and deciduous trees will have regained their leaves.

Leo with Regulus follows the bright stars of winter, perhaps chasing them off —Sirius low in the south (but the brightest star in the sky, as seen from our solar system, is no match for Jupiter and Venus). Ahead of it are Betelgeuse, Rigel, Pollux, Castor, Capella, Aldebaran and Procyon, all of them appearing above the southern horizon.

Bright stars in the remaining sky are Deneb and Vega in the north and Arcturus and Spica rising in the east in the late evening.

Jupiter has been appearing all winter long and has been well positioned above the southern horizon for quite some time, near Leo’s Regulus. The near-full moon appears near the giant planet March 29.

Venus appears very bright and brilliantly in the evening sky, high in the west, near the Pleiades. Mars appears right beneath Venus, and Uranus is very close to it, especially March 11. The crescent moon will be nearby March 22.

Saturn rises around 1 a.m. but remains low in the southern sky, albeit making a nice large triangle with Arcturus and Spica. The third-quarter moon is nearby March 12.

Neptune and Mercury are not visible this month since they rise and set virtually at the same time as the sun.

Daylight saving time began March 8. During this legislative session in Juneau, Senate Bill 6 was introduced, attempting to eliminate DST. Since Kenai and Soldotna are at 151 degrees west (of Greenwich), and since we are part of the Alaska Time Zone, our exact average noon occurs at 1:05 p.m. AST during the winter and 2:05 p.m. during the summer. Noon, by definition, should be 12:00 p.m., but Alaska is so large that that Southcentral’s local noon is pushed one hour out, and due to DST, by another hour. The extra five minutes are due to being 1 degree west of the 150-degree meridian.

That local noon is itself only an average, changing by as much as 15 minutes later and earlier, due to Earth’s axis tilt and due to Earth’s varying speed in its slightly elliptical orbit. Therefore, sunrise and sunset are equally distant from 2 p.m. ADT (or 1 p.m. AST) only a few times each year.

Spring begins in the northern hemisphere March 20, the equinox being defined as equal times of 12 hours, 0 minutes, each for day and night. Prior to that date the axis in the northern hemisphere points away from the sun, producing shorter days and less-intense heating (because the sun is lower in the sky). After that date the axis in the northern hemisphere points toward the sun, producing longer days and more-intense heating (because the sun is higher in the sky).

A solar eclipse will occur March 20, but will only be visible in Europe, Asia and northern Africa. However, solar and lunar eclipses come in pairs, and Alaska will get a total lunar eclipse April 4.

Andy Veh is an associate professor of physics, math and astronomy at Kenai Peninsula College.


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Filed under astronomy, Night Lights

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