Why are the planets always meeting up with each other?

Wednesday, March 4, 2015

Well, that is two months of the new year we have burned through, now we are starting on the last month of the first quarter of the year.

We also have two more planets appearing close to each other in our early evening sky, this time Venus will be helping us find the dim, distant planet Uranus and there will be another one next week.

First up is the bright planet Venus. If you have been following Venus for the past few weeks it has steadily risen higher each night first past Mars and now zeroing in on Uranus.

Tonight, Wednesday, March 4, the two planets can be seen in the same field of binocular view starting about an hour after local sunset.

If you have no idea of when local sunset is point your favorite web browser to www.sunrisesunset.com, enter your country, state, and city, opt for civil and astronomical twilight, and print a calendar of sunrise and sunset times for the month.

Sunrise or sunset is the time when the geometric center of the Sun crossed the horizon either rising or setting.

Civil twilight gives the time when the geometric center of the Sun is six degrees below the horizon at either sunset or sunrise. Astronomical twilight is when the Sun is 18 degrees below the horizon and is the time when the stars are first showing up -- or disappearing--and astronomical observation can begin or end.

Understand that Venus and Uranus are not really close to each other, it only looks that way. In reality Uranus is on the outer reaches of the solar system on the opposite side of the Sun from Earth; Venus is just between us in its orbit.

Uranus is at about sixth magnitude -- almost within naked-eye range -- and will be a small, blue-green dot below Venus.

If the sky is cloudy, or you forget to go out and look, not to worry. The pair will be in the same field of view until Saturday, March seventh.

If there are still problems viewing, just hang on until March 10, when Mars takes its turn pointing the way to Uranus.

Now might be a good time to answer one question I have received, "Why do the planets and the moon always seem to be lining up near each other?" Good question.

The reason is the planets (and the moon in a sense) orbit the Sun in the galactic plane, or the ecliptic as it is called. This is also why the Sun seems to appear against the various constellations of the zodiac, changing each month.

Since they are all basically in the same plane, they upon occasion appear close to each other. Mostly, I think, for our amusement.

SKYWATCH: Full moon, tonight, Wednesday, March 4. Now is a good time to look for a dark-sky pace with an unobstructed view to the west so we will have an opportunity to view the zodiacal light from March 8-21st.

The zodiacal light is sunlight reflected off the bazillions of tiny dust particles located in the galactic plane.

In the spring of the year the plane extends almost perpendicular to the western horizon and can be observed as a cone of light (if you can see the Milky Way from where you live you can see the zodiacal light) extending above the horizon in some cases almost halfway up the sky.

One more thing, Daylight Savings Time starts at 2 a.m. on Sunday, March 8, so crank your clocks ahead an hour.

NEXT WEEK: Yet another planetary meet-up, Pluto finally gets some long-deserved attention, and more astronomical blathering.

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