Tour of the Sky: April 2009

Podcast Episode Summary

This tool displays the approximate Moon phases for a given month(images are close approximations). For official phase times and dates for this month and past months are available from the U.S. Naval Observatory.

Astronomical Online Glossary

Download this month's sky map!

Northern hemisphere sky map or theSouthern hemisphere sky map so you can follow along with our viewing sessions.
Creator: Kym Thalassoudis

Southern Hemisphere Additional Information

Planets for April 2009

April will be a morning viewing month for planets with a lovely lunar meet and greet with Jupiter and Mars and an occultation of Venus. Saturn is available for evening viewers!

Beginning of the month

April 21st

• Mercury- In superior conjunction on March 31st look for Mercury at its greatest elongation east on April 26th. This will be the Northern H. best view all year. Look just between the waxing crescent Moon and the horizon just after sunset -2.1 mag (1st) to -0.4 mag (21st)

  
  April 26th

   

• Venus- Just stunning in the morning sky growing to -4.7 after mid month. Watch for the lunar occultation starting just around sunrise and ending about an hour later! Large binos and small telescope should catch the action! -3.9 mag (1st) to -4.4 mag (21st)

  
  Venus just before sunrise passing behind the Moon....and later, after sunrise, reappearing

   

• Mars- Finally starts to get brighter and over the next few months Mars will run (almost) a circle around Venus as their positions change in relation to Earth. This little game of tag within the constellations will be fun to watch for the next several months. 1.2 (1st) to 1.2 mag (21st)
  
• Jupiter- Should be high enough in the morning to be seen. (unless you are in Seattle and we have our perpetual planet zapping cloud banks) Look for Jupiter during the day on the 19th as the Moon passes close by. On the 26th pull out the telescope and see if you can catch the "fake moon" mag 5.9 44 Capricorni -1.9 mag (1st) to -1.9 mag (21st)
  
• Saturn- In eastern Leo Saturn's rings are inclined 3.8 deg towards Earth. Definitely a dramatic difference from last year! 0.6 mag (1st) to 0.6 mag (21st)

  

   

• Uranus- In Aquarius 5.9 mag (1st) to 5.9 mag (21st)
• Neptune- In Capricorn 8.0 mag (1st) to 7.9 mag (21st)
• Ceresand Eta - Finder chart from the New Zealand RAS (RASNZ) great charts! Northern Hemisphere observers this time you get to flip the chart or stand on your head!
  Vesta chart temporarily missing...use this one until site is corrected

Key Dates for April 2009

Days and Times in UT: (help with time)
Observations are for 9 pm for everyone!
Today's sunrise and sunset times or plan ahead using the US Naval Observatory Website

Occultation information can be found at the IOTA website!

Astronomical Highlights - April 2009

Date information courtesy of: RASC Observer's Handbook, Skymaps.com, Astronomical Calendar 2009, CalSky, Skymaps.com. sunrise and sunset times for your home*
Comparative lengths of day and night

Monthly Messier*

(I'm trying to find out what has happened to the NGC/IC Project homepage. It has been a standard AAGG reference for 3 years but seems to have disappeared! If you have any information on this great site please let me know....until then the images will be from: "Messier45.com" )

M41

This cluster in Canis Major is visible as a hazy patch to the naked eye just below Sirius. M41 is resolvable in binoculars and appears fairly loose in telescopes at low power.

M93

This is a small fuzzy patch of light in Puppis, partially resolvable in binoculars. The hardest part of finding this cluster in binoculars is picking it out of a fairly rich region of the milky way. Use low power to examine this cluster and the surrounding richness in a telescope. Medium power provides a nice view of the cluster itself.

M47

A bright cluster in Puppis, easily visible as a hazy patch to the naked eye. Binoculars will show a large hazy patch with many stars resolvable. Telescopes show a fairly loose cluster with stars of wide variety of magnitudes.

M46

This cluster is right next to M47 and is also visible to the naked eye. In binoculars M46 appears as a large hazy patch with no stars resolvable, giving a nice contrast to M47. In telescopes at low powers this cluster evenly fills the eyepiece. While you are here go to medium or high power and look for the planetary nebula NGC2438. It will appear as a faint uneven ring, with a blue/green color.

M50

An open cluster in Monoceros. This is a small hazy patch in binoculars, partially resolvable. Like M93, the richness of the surrounding field is the only difficulty in finding this object. This is a fairly tight cluster at low power in a telescope.

M48

Moving on to Hydra, we find another naked eye cluster. M48 is a large fuzzy patch in binoculars, partially resolvable. Use low to medium power in your telescope for a spectacular view.

M67

In the southeast portion of Cancer is another open cluster, barely visible as a fuzzy patch to the naked eye. Binoculars show M67 as a large hazy patch of light, similar to M46. Use low power to resolve this large, rich cluster in a telescope.

M44

Known as the Praesepe or Beehive Cluster, this open cluster is easily visible to the naked eye as a large, fuzzy patch bigger than the moon. Binoculars or rich field telescopes provide the best view of M44.

M81, M82

This pair of galaxies in Ursa Major are very possible to see in binoculars, they look like a pair of fuzzy stars. Both galaxies will fit into the same low power telescope field. M81 will appear as a large oval gray patch of light. M82 is a pencil like streak of light next to and perpendicular to the long axis of M81.

From the Tony Cecce, Corning, NY - Twelve Month Tour of The Messier Catalog

Comets for April 2009

• 144P/Kushida: ~ 8 mag - in Gemini, evening
• C/2007 N3/Lulin: ~8.5 mag in Gemini early evening
• C/2006 W3 ( Christensen ): ~9 mag in Pegasus, pre-dawn

Mark has developed his own website so let's all trot on over and see the pages of wonderful history he has for us this month!

Help us out by leaving a donation in the ol' PayPal hat

Music Scottish Guitar Quartet -"Romance Within You"
Marqui Adora- "Catch the Sun"
Sean Wiggins- "Mercury in Retrograde"

Earth's major motions for 2009

Planet Positions for 2009

Interesting Planet Pairing for 2009

• December 31, 2008 - Jupiter and Mercury - After sunset a little more than one degree apart in Sagittarius. Pull out the binos and telescopes because Mercury will be a mere 15 arcminutes from the globular cluster M75. All three will be together in one field of view in most home binoculars.
• January 22nd - Venus and Uranus - After sunset 1.3 degrees apart a few days later on the 29th they are joined by a waxing crescent moon.
• February 23rd - Jupiter, Mars and Mercury - In the early morning sky just before sunrise the trio are in a space about 2 degrees wide. Binoculars will be helpful but beware the quickly rising Sun. The Moon, almost invisible, will be between Mars and the Sun.
• March 23rd - Mars, Moon, Neptune, and Jupiter - Makes a nice line-up in the morning sky with Neptune just off the tip of the waning crescent moon.
• April 21st - Venus, Mars, Uranus, waning crescent Moon, Neptune and Jupiter - all in the pre-dawn sky together. First the right triangle of Venus, Mars, and Uranus followed by the waning crescent Moon and then finally by Neptune and Jupiter. Mars will be a faint 1.41 mag so binoculars will be helpful. The next day, possible occultation of Venus by the Moon. Check the IOTA website for occultations in your area.
• May 25th - Jupiter and Neptune - Jupiter is less than 1/2 degree South of Neptune in the morning sky. If you have ever had problems finding Neptune this would be a good time to try, between now and June.
• June 19th - Venus and Mars - In the pre-dawn sky just south of a waning crescent Moon. Closer to the Sun is Mercury and the Pleiades.
• August 17th - Saturn and Mercury - Very close to the Sun low in the evening sky. Much better view for Southern viewers.
• September 3rd UT 4:43 - Jupiter hides its Galilean moons. Not until 2019 will all of Jupiter's Galilean moons orbit in such a way.
• September 4th - Saturn - Not exactly a pairing but the Earth will cross the plane of the rings from south to north making the rings invisible
• October 16th - Mercury, Venus, and Saturn - All lined up in the pre-dawn sky close to the horizon. A faint waning crescent is just south of the trio.
• December 24th - Jupiter and Neptune - Just after sunset Jupiter and Neptune sit side-by-side just north of delta Capricornus and east of the "42,44,45 Cap Wall"

Phases of the Moon 2009

(click to enlarge)

Universal Time

      NEW MOON    FIRST QUARTER       FULL MOON     LAST QUARTER

       d  h  m          d  h  m         d  h  m          d  h  m
       
                 JAN.   4 11 56   JAN. 11  3 27   JAN.  18  2 46
JAN.  26  7 55   FEB.   2 23 13   FEB.  9 14 49   FEB.  16 21 37
FEB.  25  1 35   MAR.   4  7 46   MAR. 11  2 38   MAR.  18 17 47 
MAR.  26 16 06   APR.   2 14 34   APR.  9 14 56   APR.  17 13 36  
APR.  25  3 23   MAY    1 20 44   MAY   9  4 01   MAY   17  7 26
MAY   24 12 11   MAY   31  3 22   JUNE  7 18 12   JUNE  15 22 15
JUNE  22 19 35   JUNE  29 11 28   JULY  7  9 21   JULY  15  9 53  
JULY  22  2 35   JULY  28 22 00   AUG.  6  0 55   AUG.  13 18 55  
AUG.  20 10 02   AUG.  27 11 42   SEPT. 4 16 03   SEPT. 12  2 16
SEPT. 18 18 44   SEPT. 26  4 50   OCT.  4  6 10   OCT.  11  8 56  
OCT.  18  5 33   OCT.  26  0 42   NOV.  2 19 14   NOV.   9 15 56  
NOV.  16 19 14   NOV.  24 21 39   DEC.  2  7 30   DEC.   9  0 13  
DEC.  16 12 02   DEC.  24 17 36   DEC. 31 19 13

Eclipses for 2009

February 09 - Penumbral Lunar Eclipse ( see map, times): The first lunar eclipse of 2009 is one of four such events during the year. The first three eclipses are penumbral while the last (on Dec. 31) is partial. The Feb 09 event is the deepest penumbral eclipse of the year with a penumbral magnitude of 0.899. It will be easily visible to the naked eye as a dusky shading in the northern half of the Moon. The times of the major phases are listed below.

July 07 - Penumbral Lunar Eclipse ( see map, times.): July's penumbral eclipse is only of academic interest since the magnitude is just 0.156. Although the Moon will be above the horizon from most of Canada, the eclipse is so minor as to be completely invisible to the naked eye.

July 21-22 - Total Solar Eclipse ( see map, times, and animation!): To make up for the anemic lunar eclipse earlier in the month, a major total eclipse of the Sun occurs two weeks later. The path of the Moon's umbral shadow extends across India, China, a handful of Japanese islands and the South Pacific Ocean (Espenak and Anderson, 2008). A partial eclipse is seen within the much broader path of the Moon's penumbral shadow, which includes most of eastern Asia, Indonesia, and the Pacific Ocean.

August 05-06 - Penumbral Lunar Eclipse ( see map, times): A shallow penumbral eclipse occurs 15 days after the total solar eclipse. Since its magnitude is only 0.402, it will not be visible to the naked eye.

December 31 - Penumbral Lunar Eclipse ( see map, times): The last eclipse of 2009 occurs on New Year's Eve. This minor partial lunar eclipse takes place in Gemini, and is visible primarily from the Eastern Hemisphere (Figure 8). Greatest eclipse takes place at 19:23 UT when the eclipse magnitude will reach 0.0763.

Eclipse information from: NASA Eclipse Homepage, Eclipses Online (HM Nautical Almanac Office, UK in coordination with the U.S. Naval Observatory)

2009 Meteor Shower Calendar

Information and Table Template Courtesy The American Meteor Society, International Meteor Organization, and Meteors Online.

Explanation of the 2009 Meteor Shower Calendar

Shower: named for the constellation or closest star within a constellation where the radiant is located at maximum activity.

Activity Period: the dates when the ZHR (Zenith Hourly Rates) are equal to or greater than one.

Maximum: the date on which the maximum activity is expected to occur.

S.L.: the equivalent solar longitude of the date of maximum activity. Solar longitude is measured in degrees (0-359) with 0 occurring at the exact moment of the spring equinox, 90 at the summer solstice, 180 at the autumnal equinox, and 270 at the winter solstice.

Radiant: the area in the sky where shower meteors seem to appear from. This position is given in right ascension (celestial longitude) and declination (celestial latitude).

Velocity: the velocity at which shower meteors strike the Earth's atmosphere. The velocity depends on the angle meteoroids (meteors in space) intersect the Earth. Meteoroids orbiting in the opposite direction of the Earth and striking the atmosphere head-on are much faster than those orbiting in the same direction as the Earth. This velocity is measured in kilometers per second.

r: The Population Index, An estimate of the ratio of the number of meteors in subsequent magnitude classes. Simply stated: the lower the "r" value, the resulting overall mean magnitude of each shower will be brighter. "r" usually ranges from 2.0 (bright) to 3.5 (faint).

ZHR: Zenith Hourly Rate, the average maximum number of shower meteors visible per hour if the radiant is located exactly overhead and the limiting magnitude equals +6.5. Actual counts rarely reach this figure as the zenith angle of the radiant is usually less and the limiting magnitude is usually lower. ZHR is a useful tool when comparing the actual observed rates between individual observers as it sets observing conditions for all to the same standards.

Class: A scale developed by Robert Lunsford to group meteor showers by their intensity:

Class I: the strongest annual showers with ZHR's normally ten or better.

Class II: reliable minor showers with ZHR's normally three or better.

Class III: showers with widely variable rates. They may be strong one year and totally inactive the next.

Class IV: weak minor showers with ZHR's rarely exceeding three. The study of these showers is best left to experienced observers who use plotting and angular velocity estimates to determine shower association. Observers with less experience are urged to limit their shower associations to showers with a rating of I to III. These showers are also good targets for video and photographic work.

Moon: the age of the moon in days where 0 is new, 7 is first quarter, 14 is full, and 21 is last quarter. Meteor activity is best seen in the absence of moonlight so showers reaching maximum activity when the moon is less than 10 days old or more than 25 are much more favorably observed than those situated closer to the full moon.

Information from the "Observer's Handbook 2009" RASC