Astronomy News for the Month of April 2007


  This news letter is provided as a service by
The International Association for Astronomical Studies
located in Denver, Colorado. The astronomical data presented here is
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For amateur radio and scanner enthusiasts, when in the Denver metro area, please join the Colorado Astronomy Net on the Rocky Mountain Radio League repeater on a frequency of 146.94 MHz on Tuesday nights at 7PM local time.


Special Notice to Denver, CO area residents and visitors to the area:

The Plains Conservation Center in Aurora hosts Full Moon Walks every month weather permitting on or near the night of the full Moon. Visit http://www.plainsconservationcenter.org for more information and directions.


 Excerpts from JPL mission updates are provided as a public service as part
of the JPL Solar System Ambassador/NASA Outreach program.

For special JPL programs and presentations in your area visit the JPL Solar System Ambassador website.
(Click on the logo to link to the JPL SSA homepage.)


In this Newsletter...

Background screen credits:NGC5775 -Imaged March 21/22, 2001 using the 16" Kitt Peak Visitors Center telescope as part of the Advanced Observing Program.


14

The Moon

Phases

Apogee/Perigee

Moon/Planet Pairs

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The Planets & Dwarf Planets

Planetary Reports generated by "TheSky" software. These reports provide predicted data for the planets for the first of each month for the current year. The rise and set times for the Sun and the Moon for each day of the month are also included in the reports.

(All times are local unless other wise noted.)
Planetary Highlights for April - "One of the sky's prettiest sights is the blazing planet Venus floating above the horizon at dusk. This month, Venus passes south of the Pleiades, and the star cluster's diminutive sparkles make quite a sight in binoculars. Not far off, Comet 2P/Encke makes a month long hook through Aries and Cetus. Once Venus sets, Saturn rules the night - until Jupiter rises in the hours before dawn." from Astronomy Magazine, April 2007, p. 44.
Mercury - Rises about 5:56 am on the 1st and about 5:59 am by the end of the month. Mercury is best viewed during the first week of April when it will be rising about 50 minutes before the Sun. After that, Mercury is lost in the early morning twilight. Mercury shines at magnitude 0.0 on the 1st.
Venus - Dominates the evening sky soon after sunset this month. Venus sets about 10:28 pm on the 1st and about 11:28 pm by month's end. Venus is in the constellation of Taurus and shines at magnitude -4.0.
Earth - N/A.
Mars - Can be spotted in the early morning sky before sunrise this month. Mars rises at 5:02 am on the 1st and about 4:02 am by month's end. Mars is in the constellation of Aquarius. Mars shines at magnitude 1.1.
Jupiter - Rises at 12:51 am on the 1st and about 10:48 pm by month's end. Jupiter is in the constellation of Ophiuchus and shines at magnitude -2.4.
Saturn - Is visible in the early evening sky by the time the Sun sets. Saturn sets around 4:47 am on the 1st and about 2:49 am by month's end. Saturn is in the constellation of Leo and shines at a magnitude of 0.3.
Uranus - Has returned to the morning sky. Uranus rises about 5:49 am on the 1st and about 3:55 am by the end of the month. Uranus is in the constellation of Aquarius and shines at magnitude 5.9.
Neptune - Rises at 4:44 am on the 1st and about 2:48 am by month's end. Neptune is in the constellation of Capricornus and shines at magnitude 7.9.

Dwarf Planets

Ceres - Is still lost in the twilight glow and is not visible this month. Ceres returns to the morning sky in late April rising about 4:38 am by the end of the month.
Pluto - Rises about 12:11 am on the 1st and about 11:08 pm by month's end. Pluto is in the constellation of Sagittarius. Pluto shines at magnitude 13.9. As always, good luck at spotting this one.

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Astronomical Events

Meteor Showers

  • The Lyrid Meteor Shower - The Lyrids are typically visible between April 16 and 25. Maximum occurs during April 21-22. Although the maximum rate is about 10, there have been instances during the last 200 years when rates were near or over 100 per hour. The average magnitude of the meteors is near 2.4 and the speed is described as rapid. About 15% of the meteors leave persistent trains.

    For more information about Comets and Meteor Showers, visit Gary Kronk's Comets & Meteor Showers webpage.

  • Comets

  • Comet 2P/Encke swings around the Sun on the 19th. Encke arcs through the constellation of Aries and into Cetus. The best time to catch a glimpse of Comet Encke is during the first week of April. Comet Encke won't brighten to much more than about 6th magnitude, so binoculars or a telescope will be needed to spot Encke low on the western horizon about an hour after sunset.
  • Comet 96P/Machholz can be spotted before sunrise passing through the constellation of Pegasus later in the month.

    For information, orbital elements and ephemerides on observable comets, visit the Observable Comets page from the Harvard-Smithsonian Center for Astrophysics.

    For more information about Comets and Meteor Showers, visit Gary Kronk's Comets & Meteor Showers webpage.


  • Eclipses

  • No eclipse activity this month.
  • Ocultations

    IOTA Logo

  • More information on occultations can be found by clicking the IOTA logo.
  • Asteroids

    (From west to east)
    • Iris is in the constellation of Gemini.

    • Parthenope is in the constellation of Virgo.

    • Juno is at opposition on the 9th in the constellation of Virgo.

    • Vesta is in the constellation of Ophiuchus.

    • Information about the Minor Planets can be found at the Minor Planet Observer website.

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    Planetary/Lunar Exploration Missions

    (Excerpts from recent JPL mission updates)
    Cassini - March 27, 2007 - Cassini Images Bizarre Hexagon on Saturn
    Saturn's Active North Pole

    "Pasadena, Calif. -- An odd, six-sided, honeycomb-shaped feature circling the entire north pole of Saturn has captured the interest of scientists with NASA's Cassini mission.

    NASA's Voyager 1 and 2 spacecraft imaged the feature over two decades ago. The fact that it has appeared in Cassini images indicates that it is a long-lived feature. A second hexagon, significantly darker than the brighter historical feature, is also visible in the Cassini pictures. The spacecraft's visual and infrared mapping spectrometer is the first instrument to capture the entire hexagon feature in one image.

    "This is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides," said Kevin Baines, atmospheric expert and member of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We've never seen anything like this on any other planet. Indeed, Saturn's thick atmosphere where circularly-shaped waves and convective cells dominate is perhaps the last place you'd expect to see such a six-sided geometric figure, yet there it is."

    Cassini Imaging Team

    For the latest mission status reports, visit Cassini Mission Status webpage. The speed and location of the spacecraft along its flight path can be viewed on the "Where is Cassini Now?" webpage.

    New Horizons - March 30, 2007 - Storm Spectra

    "These images, taken with the LEISA infrared camera on the New Horizons Ralph instrument, show fine details in Jupiter's turbulent atmosphere using light that can only be seen using infrared sensors. These are "false color" pictures made by assigning infrared wavelengths to the colors red, green and blue. LEISA (Linear Etalon Imaging Spectral Array) takes images across 250 IR wavelengths in the range from 1.25 to 2.5 microns, allowing scientists to obtain an infrared spectrum at every location on Jupiter. A micron is one millionth of a meter."

    For more information on the New Horizons mission - the first mission to the ninth planet - visit the New Horizons homepage: http://pluto.jhuapl.edu/ for more information about the mission.

    Pack Your Backpack

    Calling all explorers! Tour JPL with our new Virtual Field Trip site. Stops include Mission Control and the Rover Lab. Your guided tour starts when you select a ÓfaceÓ that will be yours throughout the visit. Cool space images and souvenirs are all included in your visit.

    Past, Present, Future and Proposed JPL Missions - http://www.jpl.nasa.gov/missions

    Visit JPL's mission pages for current status.

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       Mars Missions

    Mars Global Surveyor - No new news since January 10, 2007 - Panel Will Study Mars Global Surveyor Events

    "NASA has formed an internal review board to look more in-depth into why NASA's Mars Global Surveyor went silent in November 2006 and recommend any processes or procedures that could increase safety for other spacecraft.

    Mars Global Surveyor launched in 1996 on a mission designed to study Mars from orbit for two years. It accomplished many important discoveries during nine years in orbit. On Nov. 2, the spacecraft transmitted information that one of its arrays was not pivoting as commanded. Loss of signal from the orbiter began on the following orbit.

    Mars Global Surveyor has operated longer at Mars than any other spacecraft in history and for more than four times as long as the prime mission originally planned."

    Every six months, a new suite of MGS MOC data are archived with the NASA Planetary Data System (PDS).

    Information about how to submit requests is online at the new Mars Orbiter Camera Target Request Site, at http://www.msss.com/plan/intro"

    Newly-released MOC images can be seen in the MOC Gallery, a website maintained by Malin Space Science Systems, the company that built and operates MOC for the Jet Propulsion Laboratory and NASA.

    Visit the MGS pages at http://mars.jpl.nasa.gov/mgs/index.html. There are over 200,000 images of Mars from the MGS, check out the newest MGS images of the surface of Mars.

    Mars Odyssey Orbiter - March 27, 2007 - Mars Odyssey Mission Status

    "Engineers for NASA's Mars Odyssey mission are examining data from the orbiter to determine whether onboard backup systems never used by the 6-year-old spacecraft could still be available if needed.

    Odyssey reported last week that a power processing component of the backup, or "B-side," systems had stopped working. The component, the high-efficiency power supply, has a twin that is continuing to serve the "A-side" hardware, which is operating normally. Odyssey has stayed on its A-side systems, including the A-side flight computer, since launch on April 7, 2001. However, the A-side power supply cannot serve most systems on the B-side, including the backup B-side computer. If engineers do not determine a way to restore the B-side power supply, most of the backup hardware would not be available, if it were ever needed."

    "A simulated fly-through using the newly assembled imagery is available online.

    The fly-through plus tools for wandering across and zooming into the large image are at http://themis.asu.edu."

    Mars Odyssey THEMIS Images
    Thermal Emission Imaging System (THEMIS) website: http://themis.asu.edu/

    March 26-30, 2007

    The following new images from the Mars Odyssey spacecraft are now available:

    The Odyssey data are available through a new online access system established by the Planetary Data System at: http://starbrite.jpl.nasa.gov/pds/"

    Visit the Mars Odyssey Mission page.

    Mars Exploration Rover Mission (Spirit and Opportunity) - March 27, 2007

    Spirit Status: Spirit Studies Rocks in Vicinity of "Home Plate" - sol 1141-1144, March 23, 2007

    "Spirit remains healthy and spent much of the week studying a new rock target on "Mitcheltree Ridge" called "Torquas." Scientists are trying to understand what relationship Mitcheltree Ridge has to "Home Plate" -- for example, whether it is an extension of Home Plate or an entirely different rock layer, and whether it has similar composition or morphology.

    Torquas is nicknamed after a dried-up seabed covered with moss in the Barsoom science fiction saga by Edgar Rice Burroughs."

    Opportunity Status: Opportunity Begins Imaging of 'Cape of Good Hope' - sol 1118-1125, March 27, 2007

    "Opportunity is healthy and making progress on the imaging campaign of "Cape St. Vincent."

    On Sol 1116, Opportunity experienced a fault due to a known but rare race condition in the flight software. This race condition fault has now occurred three times in 1,122 sols for Opportunity and three times in 1,143 sols for Spirit. Essentially, while the rover was booting up in the morning, two sequences were competing to complete first. The lower priority task was stopped by the higher priority task and when the former attempted to complete, it was locked out of the rover's memory. The software did as it is supposed to and threw up a red flag to programmers and awaited its next commands.

    On Sols 1117 and 1118 were spent recovering the rover from the fault. Opportunity spent sols 1119 and 1120 resting since these sols fell on an Earth weekend (the project no longer has the resources to bring in a weekend sequencing team).

    On Sol 1121, Opportunity drove to a position on the "Cape of Good Hope" to image the first half of a long baseline stereo image of Cape St. Vincent. On Sol 1123, Opportunity will bump 2.5 meters (8.2 feet) to image the second half of the Cape St. Vincent stereo image.

    The remainder of the sols were spent obtaining remote sensing science."

    Landing sites

    Visit the Mars Exploration Rover page.

    Mars Reconnaissance Orbiter - March 22, 2007 - Mars Reconnaissance Orbiter Mission Status

    "NASA's Mars Reconnaissance Orbiter put itself into safe mode -- a precautionary status with minimized activities -- on March 14. It remained healthy and in communication with Earth, but with no science observations, while the flight team examined engineering data. On March 20, the team brought the spacecraft back out of safe mode.

    Science instruments were powered up March 21 and are resuming normal science operations today, March 22.

    When it went into safe mode, the spacecraft switched, for the first time in the mission, to a backup ("B") duplicate flight computer on board. Diagnosis of the "A" computer has not yet revealed what caused the switch to the B side."

    More information about the mission is available online at http://www.nasa.gov/mro.

    Mars Missions Status

    New Mars missions are being planned to include several new rover and sample collection missions. Check out the Mars Missions web page and the Mars Exploration page.

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    Links and Other Space News

    (If you have a link you would like to recommend to our readers, please feel free to submit it.)

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    Astronomical Lexicon

    Definitions of astronomical terms. Many of the astronomical terms used in this newsletter are defined here.

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    UT Logo

    Read the Universe Today Newsletter by clicking on the logo.

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    Acknowledgments and References

    Much of the information in this newsletter is from Astronomy® Magazine (Kalmbach Publishing), JPL mission status reports, the Internet, "Meteor Showers - A descriptive Catalog" by Gary W. Kronk, Sky & Telescope web pages, and other astronomical sources that I have stashed on my bookshelves.

    The author will accept any suggestions, constructive criticisms, and corrections. Please feel free to send me any new links or articles to share as well. I will try to accommodate any reasonable requests. Please feel free to send questions, comments, criticisms, or donations to the email address listed below. Enjoy!

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    Keep looking UP!
    73 from KIØAR

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