Whats Up, Ron? is a monthly almanac for Northern American astronomersastras

WHAT'S UP?

by Ronald A. Leeseberg, the Star Geezer

March 2011 - Vol. 15 No. 3

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Features: Calendar | Lunar Almanac | Monthly Topic

This Month's Night Sky - NOTE: The next paragraph describes the sky as it appears at 10 pm EST (11 pm EDT) near mid- month. The sky also looks this way at 11 pm EST (midnight EDT) during the beginning of the month and at 9 pm EST (10 pm EDT) by month's end.

Angular Measurement Review: It is interesting to note that the relationship between the angle subtended by combinations of fingers on your fully outstretched arm are the same for all viewers. This is due to the fact that the hand's size is proportional to the arm's length. A shorter arm is attached to a smaller hand while a longer arm is attached to a larger hand, thus the angle measured remains the same. If you hold your arm fully outstretched, your little finger, when sighted down your arm, is one degree wide. Your three middle fingers is five degrees, your fist, 10 degrees, and the distance between your little finger and your pointer finger is 15 degrees no matter what your age or size.

Spring finally arrives! The constellations Taurus, with M45 (the Pleiades), a "dipper-like" asterism), Orion and the Winter Triangle are now sinking in the W. Castor and Pollux (the Gemini "twins") are shining in the NW while Capella (Auriga) glows above them. Regulus (Leo) shines high in the S as the wandering constellation Hydra appears to create a void below since it has no bright stars. The "Big Dipper" asterism (Ursa Major) high in the NE has appeared to "rotate" so its "handle" is now nearly horizontal. Spica (Virgo) and Arcturus (Bootes) are now rising in the E.

MERCURY makes its best evening appearance of the year. It should be visible, very low on the W horizon from the second through the last week of this month. VENUS remains the bright "morning star". It is visible in the SE about two hours before sunrise, then fades from view as the sun rises. MARS is lost in the sun's glare this month. JUPITER sets in the W about two hours after sunset. SATURN shines in the SE all night this month. It rises about two hours after sunset at the beginning of the month but at sunset by month's end. The SUN reaches the equinox on the 20th. of this month, thus Spring begins in the Northern Hemisphere.

Calendar of Events

NOTE: For those observers not in the ET zone, convert the calendar times to your zone's time by subtracting one hour for CT, two for MT and three for PT. Don't forget to adjust for Daylight Savings Time when necessary by subtracting one hour from your planisphere's time.; Dawn and dusk times must also be corrected. See your local newspaper, TV news, or cable TV's Weather Channel for sunrise and sunset times. Unfortunately some of these events may occur during daylight hours in your area.

DATE EVENT
01
Look ESE about an hour before sunrise to see a conjunction of the crescent Moon and Venus.
05

Using binoculars, look W, at dusk, to see Mercury very low on the horizon. The crescent Moon is above and to the right while Jupiter floats nigh above and to the left.

06
Look W at dusk to see a distant conjunction of the crescent Moon and Jupiter, to the left.
Mar 13
Daylight-Savings Time (DST) begins at 2 AM. If this occurs in your area, be sure to subtract one hour from your planisphere's reading.
13-16
Daylight-Savings Time (DST) begins at 2 AM. If this occurs in your area, be sure to subtract one hour from your planisphere's reading.
17-28
At dusk Mercury remains around 10 degrees above the W horizon. Don't miss it!
20
Spring begins in the Northern Hemisphere. The equinox occurs at 7:21 PM EDT.
20-21
The bright star, Spica (Virgo), remains in pseudo-conjunction with the Moon all night.
3/21-4/5
There is still time to view spring's Zodiacal Light. Begin looking from a dark site with a clear view of the W horizon about an hour and a quarter after sunset. (See last month's issue for details.)
31
Look ESE at dawn to see a conjunction Venus and the crescent Moon.
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Lunar Almanac for March 2011

Phases of the Moon Phase and Date(s)

Best viewed before local midnight

New
04

Deep Space Objects

1st. Qtr
12

Planets & Moon

Full
19

Moon

Last
Qtr 26

Deep Space & Planets

Topic of the month: Sidewalk Astronomy, Telescope Mounts

From the point of view of the Sidewalk Astronomer, the telescope's mount is almost more important than the telescope itself. There are a confusing number of different mounts:

These mounts fall into two general categories: (1) equatorial and (2) altazimuth. The advantage of the equatorial mount is that it can easily track celestial objects. One only has to move one (Declination) axis since the telescope follows the rotation of the Earth around its polar axis when properly set up.

Unfortunately this is difficult, if not impossible, for the Sidewalk Astronomer, especially if children are involved.

Remember that the purpose of Sidewalk Astronomy is to show the brighter celestial objects to many people at a time. Often children must stand on some sort of ladder to reach the telescope's eyepiece. Naturally, the first thing the child grabs is the eyepiece...so much for equatorial mounts and their precise polar alignments!

For my street astronomy, I use refractors. My 2.4" solar telescope has an f/number of f/11 (660mm/60mm) and my 120mm telescope has an f/number of f/8.3 (1000/120). Since, due to the usual intense street lighting, only very bright celestrial objects are visible through the haze, greater magnification of the Sun, Moon and the bright planets and bright, but compact, deep space objects is more appropriate. These smaller refractors are easier to set up and transport. Also, since they are sealed, dust is less of a problem, and they reach equalized temperature very quickly.

Mount & Tripod I use here in Florida

The advantage of the alt-azimuth mount is the ease and speed of refinding a bright object once the telescope's orientation has been lost. Since we are not interested in capturing the very last photon emitted by our target, and must find the target very quickly once lost, the alt-azimuth mount is the most useful for me.

--See you next month!
Ron, the star geezer

This installment of "Whats Up?" is ©2011 Ronald A. Leeseberg, encoded by Dawn Jenkins for Astra's Stargate. Images used in this installment of "Whats Up?, Ron"are ©2011 by Ronald A. Leeseberg

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