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

WHAT'S UP?

by Ronald A. Leeseberg, the Star Geezer

July 2011 - Vol. 15 No. 7

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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.

Blue-white Vega (Lyra) shines brilliantly high overhead, leading the stars of the "Summer Triangle" asterism. Although Arcturus (Bootes) and Spica (Virgo) are about to sink below the SW horizon, Antares (Scorpius) can still be seen there. The stars of the dim constellations, Scorpius and Sagittarius are at their best in the S this month. Capella (Auriga) glitters low in the N while on the E horizon, the stars of the Great Square of Pegasus are rising. Fall is coming!

Look W. to see MERCURY appear as the glow of twilight ends while the night sky darkens. At the beginning of the month it will set shortly after the crescent Moon. If you have access to a telescope, Mercury will appear as a gibbous (football-shaped) disc. NOTE: Both of the inferior (those that orbit between the Earth and the Sun) planets show phases like our Moon ... and for the same reason. VENUS appears low on the ENE horizon before dawn early in the month. By the end of the month’s second week, it will disappear into the Sun’s glow, not to reappear again until late in September. MARS appears to travel across the Constellation Taurus in the night sky. It will appear slightly dimmer that Taurus’ brightest star, Aldebaran, but nearly the same reddish color. JUPITER competes with Saturn as this month’s “poster planet”. It is the brightest planet in the night sky, rising at about 2 AM on the first of the month and two hours earlier by month’s end. If you have access to a telescope, you will be able to see the two dark equatorial bands and, of course, you will be able to observe the dance of its four bright moons, Io, Europa, Ganymede and Callisto, lined up in an almost straight line. Golden-colored SATURN appears as a bright object in the night sky some 30 degrees above the SW horizon about an hour after Sunset. Its ring system become more noticeable this month as it tilts more to our line of sight. Through the telescope, you can also observe Titan, its largest Moon.

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
02

Look WNW to see a conjunction (5 degrees) of the Moon and Mercury about a half hour after Sunset. It forms a “triangle” with the Moon (below and to the left) and the bright star Pollux and its “twin” Castor (Gemini) to the right.

06

Look for a pseudo conjunction (5 degrees) of Mars and the bright star Aldebaran (Taurus) at 10 PM.

Mercury is in pseudo conjunction with the Beehive star Cluster (M44) in Constellation Cancer. It is very low on the horizon, a difficult target!)

07
Look for a conjunction of the Moon and Saturn at midnight.
20
Mercury reaches its greatest elongation (when a planet is its greatest distance from the Sun) usually making it easiest to observe at 1 AM.
23
Look ENE at 5 AM to see a conjunction (5 degrees) of Jupiter and the Moon at 9 PM.
30
The Southern Delta Aquarid meteor shower peaks in the S at about 4 AM. Its radiant (apparent source of the meteors) is in the Constellation Aquarius. At its best, and from a very dark site, only 15-20 events/hour will be visible. However, the new moon occurs on the same day, so it won’t interfere with your viewing. Also this rate should occur one or two day on each side of the peak. This shower is active from July 12th through August 23rd.
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Lunar Almanac for July 2011

Phases of the Moon Phase and Date(s)

Best viewed before local midnight

New
01

Deep Space Objects

1st. Qtr
08

Planets & Moon

Full
15

Moon

Last
Qtr 30

Deep Space & Planets

Topic of the month: Solar Astronomy

As it becomes more difficult to find a truly dark site for night time astronomy, especially in urban areas, some of us have turned to the study of our Sun.

This month we will discuss some methods of visual solar astronomy. The two regions of the Sun available for visual study by amateurs are the PHOTOSPHERE and the CHROMOSPHERE.

NOTE: I CANNOT STRESS ENOUGH THE IMPORTANCE OF PROPER EYE PROTECTION WHEN VIEWING THE SUN! ONE SLIP AND YOU COULD SEE "SUN SPOTS" (CAUSED BY NEARLY INSTANTANEOUS EYE DAMAGE) FOR THE REST OF YOUR LIFE!!

The Photosphere is usually regarded as the "surface" of the Sun whose most prominent features are SUNSPOTS. These are the relatively cooler regions of the Sun's surface that appear through the PROPERLY FILTERED telescope as "holes". It is appropriate to use one of the commercially available glass or plastic full aperture filters to cover the objective of your telescope.

NEVER USE THE EYEPIECE FILTER SUPPLIED WITH SOME OLDER TELESCOPES! THE INTENSE HEAT GENERATED BY ALLOWING SUN LIGHT TO PASS, UNFILTERED, THROUGH THE TELESCOPE COULD EASILY CRACK AN EYEPIECE FILTER CAUSING INSTANT PARTIAL BLINDNESS!

Most commercial aperture filters pass only one thousandth of one percent of visible solar light while filtering out the IR (InfraRed) and UV (UltraViolet) radiation.

A special telescope, Coronado's PST (Personal Solar Telescope), is now available at a fairly reasonable price to us "impecunious enthusiasts". Since this telescope is mostly filter, it needs no further filtration for safe viewing. The PST filters out all of the sun's light except for a very narrow band of red light at a wavelength of 6563 angstroms. (About 500,000 human hairs would be one angstroms wide!) This telescope allows amateurs to see the sun anytime it is in the sky as it would appear during a very rare total solar eclipse. The PST shows the sun's chromosphere, which is the sun's "atmosphere", that region above the photosphere that allows us to see Prominences, Arches and Spicules.

Ron's Solar Telescopes

The image above shows the portable setup I use when give solar programs. The white telescope gives a view of the Photosphere while the piggyback gold telescope gives a view of the Chromosphere. Note the absence of a telescopic finder (safety feature) and the presence of a sun finder (on the left side of the white telescope) that allows me to track the sun while standing with my back to the sun. Most of my public program presentation telescopes use manual tracking because many folks, when viewing, tend to grasp the telescope's eyepiece, which often defeats the tracking motors in an automated system. When that happens the system must be realigned which takes too much time to be practical. This photo was taken in my east central Ohio roll- roof observatory.

There are other optical techniques available to the amateur astronomer for solar observation. One is spectroscopy, which we will discuss next month.

--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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