Astronomy News for the Month of April 2013

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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.

The Month At-A-Glance
A calendar displaying the daily astronomical events.


The Moon



Moon/Planet Pairs

For reference: The Full Moon subtends an angle of 0.5°.

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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 otherwise noted.)

Planetary Highlights for Aperil - Jupiter and Saturn are still the dominant planets this month. Venus and Mars are hidden behind the Sun. Mercury makes a brief appearance early in the month in the morning sky. Uranus and Neptune are will return to the morning sky late in the month. Comet PANSTARRS remains visible through binoculars and the Lyrid meteor shower peaks.
Mercury - Having just passed greatest western elongation (28° above the eastern horizon) on March 31st, Mercury is visible during the first week of April low on the eastern horizon. Mercury rises at 5:47 a.m. and about 5:38 a.m. by month's end. Mercury moves from the constellation of Aquarius into Pisces shining at magnitude 0.2 on the 1st.
Venus - Is still lost behind the Sun and is not visible this month. Venus will return to the evening sky in May. Venus moves from the constellation of Pisces into Aries this month.
Earth - N/A.
Mars - Is in conjunction with the Sun on the 17th. Mars is also not visible this month. Mars moves from the constellation of Pisces into Aries this month. Mars will return to the morning sky in June.
Jupiter - Dominates the evening sky all month. Jupiter sets at 12:24 a.m. on the 1st and about 10:49 p.m. by month's end. Jupiter is in the constellation of Taurus shining at magnitude -2.0.
Saturn - Reaches opposition on the 28th, rising as the Sun sets. Saturn is at its best for the year. Saturn rises at 9:30 p.m. on the 1st and about 7:21 p.m. by month's end. Look to the east to spot Saturn in the evening. The view through a telescope reveals the ring system tilted 18° to our line of site, making the view of the ringed planet quite spectacular. Saturn is in the constellation of Libra shining at magnitude 0.1 at opposition.
Uranus - Rises at 6:40 a.m. on the 1st and about 4:46 a.m. by month's end. Uranus is barely visible in the east soon after the Sun rises with binoculars or a small telescope during the last half of the month. Uranus is in the constellation of Pisces shining at magnitude 5.9.
Neptune - Is visible in the morning sky this month rising at 5:18 a.m. on the first and about 3:22 a.m. by month's end. Neptune is in the constellation of Aquarius shining at magnitude 7.9.

Dwarf Planets

Ceres - Ceres sets at 3:08 a.m. on the 1st and about 1:55 a.m. by month's end. Look for Ceres trailing Jupiter by a couple of hours. Ceres moves through the constellation of Auriga into Gemini shining at magnitude 8.7.
Pluto - Is visible in the morning sky rising at 2:14 a.m. on the 1st and about 12:16 a.m. by month's end. Pluto is in the constellation of Sagittarius shining at magnitude 14.1.

As always, good luck at spotting these two, a large telescope and dark skies will be needed.

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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. -- However, this month, the Moon will interfere with viewing most of the meteors except for the brightest.

    For more information about Meteor Showers, visit Gary Kronk's Meteor Showers Online web page.

  • Comets

  • Comet C/2011 L4 PANSTARRS will pass by the Andromeda Galaxy (M31) on April 4th and 5th on its way towards the constellation of Cassiopeia, however, only shining at 5th magnitude will be difficult to spot without binoculars or a small telescope under relatively dark skies. Look towards the northwest soon after sunset and again in the northeast before sunrise to spot Comet PANSTARRS.

  • 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, visit Gary Kronk's webpage.

  • Eclipses

  • A partial lunar eclipse occurs on the 25th across most of the Eastern hemisphere.

  • Observational Opportunities

  • Jupiter dominates the evening sky all month.
  • Saturn reaches opposition this month so will be well placed in the east soon after sunset.
  • Comet PANSTARRS is still visible both in the evening and early morning skies.
  • The Lyrid meteor shower peaks on the 22nd.
  • Asteroids

    (From west to east)
    • Vesta is in the constellation of Orion.
    • Amphitrite is in the constellation of Leo.
    • Eunomia is in the constellation of Hydra.
    • Irene is in the constellation of Leo.

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

    IOTA Logo

  • Information on various occultations can be found by clicking the IOTA logo.
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    Planetary/Lunar Exploration Missions

    (Excerpts from recent JPL mission updates)
    Cassini - March 27, 2013
    Saturn is Like an Antiques Shop, Cassini Suggests

    "A new analysis of data from NASA's Cassini spacecraft suggests that Saturn's moons and rings are gently worn vintage goods from around the time of our solar system's birth.

    Though they are tinted on the surface from recent "pollution," these bodies date back more than 4 billion years. They are from around the time that the planetary bodies in our neighborhood began to form out of the protoplanetary nebula, the cloud of material still orbiting the sun after its ignition as a star. The paper, led by Gianrico Filacchione, a Cassini participating scientist at Italy's National Institute for Astrophysics, Rome, has just been published online by the Astrophysical Journal.

    "Studying the Saturnian system helps us understand the chemical and physical evolution of our entire solar system," said Filacchione. "We know now that understanding this evolution requires not just studying a single moon or ring, but piecing together the relationships intertwining these bodies."

    Data from Cassini's visual and infrared mapping spectrometer (VIMS) have revealed how water ice and also colors -- which are the signs of non-water and organic materials -- are distributed throughout the Saturnian system. The spectrometer's data in the visible part of the light spectrum show that coloring on the rings and moons generally is only skin-deep."

    Raw images are available at

    Cassini Imaging Team

    For the latest mission status reports, visit Cassini Mission Status web page. The speed and location of the spacecraft along its flight path can be viewed on the Present Position webpage.

    New Horizons - February 28, 2013
    Pluto Moons: The Votes Are In

    "The public has spoken, choosing candidate names for Pluto's newest and smallest moons. "Vulcan" and "Cerberus" topped the list after more than 450,000 total votes were cast.Read More."

    LORRI Looks Back

    New Horizons gallery

    Find New Horizons in the iTunes App Store here.

    For more information on the New Horizons mission - the first mission to the ninth planet - visit the New Horizons home page.

    Dawn - January 03, 2013
    Picture This: Vesta's Dark Materials in Dawn's View
    Full image and caption

    "A new study of images from NASA's Dawn mission examines remarkable, dark-as-coal material that speckles the surface of the giant asteroid Vesta. Scientists are using the images, taken by Dawn's framing camera, to understand the impact environment early in Vesta's evolution. In the most comprehensive analysis of the dark material to date, Dawn scientists describe how this carbon-rich material tends to appear around the edges of two giant impact basins in Vesta's southern hemisphere. The analysis suggests that the dark material was most likely delivered by the object that created the older of the two basins, known as Veneneia, about 2 to 3 billion years ago. Some of those materials were later covered up by the impact that created the younger basin, Rheasilvia."

    Dawn's Virtual Flight over Vesta

    A gallery of images can be found online.

    For more information on the Dawn mission, visit the Dawn home page.

    MESSENGER - March 26, 2013
    Newly Named Mercury Craters Honor Hawaiian Guitarist, Beloved Young Adult Author

    "The International Astronomical Union (IAU) -- the arbiter of planetary and satellite nomenclature since its inception in 1919 -- recently approved a proposal from the MESSENGER Science Team to assign names to nine impact craters on Mercury. In keeping with the established naming theme for craters on Mercury, all of the newly designated features are named after famous deceased artists, musicians, or authors or other contributors to the humanities. The newly named craters are

    • Alver, for Betti Alver (1906-1989), an Estonian writer who rose to prominence in the 1930s, toward the end of Estonian independence and on the eve of World War II. She published her first novel, Mistress in the Wind, in 1927. She also wrote several short stories, poetry, and translations.

    • Donelaitis, for Kristijonas Donelaitis (1714-1780), a Lutheran pastor who was considered one of the greatest Lithuanian poets. He is best known for The Seasons, considered the first classic Lithuanian poem. It depicts the everyday life of Lithuanian peasants. His other works include six fables and a tale in verse.

    • Flaiano, for Ennio Flaiano (1910-1972), an Italian screenwriter, playwright, novelist, journalist, and drama critic especially noted for his social satires. He became a leading figure of the Italian motion-picture industry after World War II, collaborating with writer Tullio Pinelli on the early films of writer and director Federico Fellini.

    • Hurley, for James Francis "Frank" Hurley (1885-1962), an Australian photographer and adventurer. He participated in several expeditions to Antarctica and served as an official photographer with Australian Imperial Forces during both world wars. The troops called him "the mad photographer," because he took considerable risks to obtain photographs.

    • L'Engle, for Madeleine L'Engle (1918-2007), an American writer best known for young-adult fiction, particularly the award-winning A Wrinkle in Time and its sequels: A Wind in the Door, A Swiftly Tilting Planet, Many Waters, and An Acceptable Time. Her works reflect both her Christian faith and her strong interest in modern science.

    • Lovecraft, for Howard Phillips Lovecraft (1890-1937), an American author of horror, fantasy, and science fiction regarded as one of the most influential horror writers of the 20th Century. He popularized "cosmic horror," the notion that some concepts, entities, or experiences are barely comprehensible to human minds, and those who delve into such topics risk their sanity.

    • Petofi, for Sandor Petofi (1823-1849), a Hungarian poet and liberal revolutionary. He wrote the Nemzeti dal (National Poem), which is said to have inspired the Hungarian Revolution of 1848 that grew into a war for independence from the Austrian Empire.

    • Pahinui, for Charles Phillip Kahahawai "Gabby" Pahinui, (1921-1980), a Hawaiian guitar player considered to be one of the most influential slack-key guitar players in the world. His music was a key part of the "Hawaiian Renaissance," a resurgence of interest in traditional Hawaiian culture during the 1970s.

    • Roerich, for Nicholas Roerich (1874-1947), a Russian painter and philosopher who initiated the modern movement for the defense of cultural objects. His most notable achievement was the Roerich Pact of 1935, an international treaty signed by India, the Baltic states, and 22 nations of the Americas (including the United States), affirming that monuments, museums, scientific, artistic, educational, and cultural institutions and their personnel are to be considered neutral in times of war unless put to military use.

    Ray Espiritu, a mission operations engineer on the MESSENGER team, submitted Pahinui's name for consideration. "I wanted to honor the place where I grew up and still call home even after many years away," he says. "The Pahinui crater contains a possible volcanic vent, and its name may inspire other scientists as they investigate the volcanic processes that helped to create Mercury, just as investigation of Hawaiian volcanoes helps us understand the volcanic processes that shape the Earth we know today."

    These nine newly named craters join 95 other craters named since the MESSENGER spacecraft's first Mercury flyby in January 2008."

    The MESSENGER app is available for download from iTunes.

    For more information on the MESSENGER mission, visit the MESSENGER home page.

    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 "face" 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 -

    Visit JPL's mission pages for current status.

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                   Mars Missions

    Be A Martian


    JMARS is an acronym that stands for Java Mission-planning and Analysis for Remote Sensing. It is a geospatial information system (GIS) developed by ASU's Mars Space Flight Facility to provide mission planning and data-analysis tools to NASA's orbiters, instrument team members, students of all ages, and the general public.

    Mars Science Laboratory - Curiosity - March 25, 2013
    Curiosity Resumes Science Investigations

    "PASADENA, Calif. - NASA's Mars rover Curiosity has resumed science investigations after recovery from a computer glitch that prompted the engineers to switch the rover to a redundant main computer on Feb. 28.

    The rover has been monitoring the weather since March 21 and delivered a new portion of powdered-rock sample for laboratory analysis on March 23, among other activities.

    "We are back to full science operations," said Curiosity Deputy Project Manager Jim Erickson of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

    The powder delivered on Saturday came from the rover's first full drilling into a rock to collect a sample. The new portion went into the Sample Analysis at Mars (SAM) instrument inside the rover, which began analyzing this material and had previously analyzed other portions from the same drilling. SAM can analyze samples in several different ways, so multiple portions from the same drilling are useful.

    The Rover Environmental Monitoring Station (REMS) is recording weather variables. The Radiation Assessment Detector (RAD) is checking the natural radiation environment at the rover's location inside Gale Crater."

    To follow the Mars Curiosity rover and NASA on Foursquare, visit: and

    For information about NASA's partnership with Foursquare, visit:

      Mars Rover Landing - Free for the Xbox (requires Kinect)

      Visit the Mars Science Laboratory page.

    Mars Exploration Rover Mission (Spirit and Opportunity) - March 26, 2013

    SPIRIT UPDATE: Spirit Remains Silent at Troy - sols 2621-2627, May 18-24, 2011:

    "No communication has been received from Spirit since Sol 2210 (March 22, 2010).

    More than 1,300 commands were radiated to Spirit as part of the recovery effort in an attempt to elicit a response from the rover. No communication has been received from Spirit since Sol 2210 (March 22, 2010). The project concluded the Spirit recovery efforts on May 25, 2011. The remaining, pre-sequenced ultra-high frequency (UHF) relay passes scheduled for Spirit on board the Odyssey orbiter will complete on June 8, 2011.

    Total odometry is unchanged at 7,730.50 meters (4.80 miles)."

    OPPORTUNITY UPDATE: Opportunity Moves Into Place for Quiet Period of Operations - sols 3255-3260, Mar. 21, 2013-Mar. 26, 2013 :

    "Opportunity has moved into position for the coming three-week solar conjunction period at "Cape York" on the rim of Endeavour Crater.

    This location, called 'Big Nickel,' is the last in-situ (contact) target before the rover departs from Cape York, once solar conjunction is concluded.

    Solar conjunction is when the Sun comes between Earth and Mars, which occurs about once every 26 months. During this time there will be diminished communications to Opportunity. The team will suspend sending the rover new commands between April 9 and April 26. The rover will continue science activities using a long-term set of commands to be sent beforehand. No new images are expected to be returned during this time.

    On Sol 3255 (March 21, 2013), after completing the investigation of the 'Newberries' at the location called 'Kirkwood,' Opportunity drove over 82 feet (25 meters) straight north toward the location called 'Big Nickel.' On Sol 3257 (March 23, 2013), the rover completed the approach to 'Big Nickel' with a 13-foot (4-meter) drive. In order to reach a specific surface target, Opportunity performed a modest, 0.8 inch (2-centimeter) bump on Sol 3260 (March 26, 2013).

    With the rover precisely positioned, the plan ahead is to sequence the robotic arm to collect a Microscopic Imager (MI) mosaic of the target, called 'Esperance' and place the Alpha Particle X-ray Spectrometer (APXS) for an overnight integration.

    On Sols 3255, 3256 and 3257 (March 21, 22 and 23, 2013), Opportunity benefitted from some dust cleaning of the solar arrays, improving energy production.

    As of Sol 3260 (March 26, 2013), the solar array energy production was 590 watt-hours with an atmospheric opacity (Tau) of 0.760 and an improved solar array dust factor of 0.654.

    Total odometry is 22.15 miles (35.65 kilometers)."

    Landing sites

    Visit the Mars Exploration Rover page.

    Mars Reconnaissance Orbiter Mission - March 07, 2013
    NASA Helps See Buried Mars Flood Channels in 3-D

    "PASADENA, Calif. -- NASA's Mars Reconnaissance Orbiter has provided images allowing scientists for the first time to create a 3-D reconstruction of ancient water channels below the Martian surface.

    The spacecraft took numerous images during the past few years that showed channels attributed to catastrophic flooding in the last 500 million years. During this period, Mars had been otherwise considered cold and dry. These channels are essential to understanding the extent to which recent hydrologic activity prevailed during such arid conditions. They also help scientists determine whether the floods could have induced episodes of climate change.

    The estimated size of the flooding appears to be comparable to the ancient mega-flood that created the Channeled Scablands in the Pacific Northwest region of the United States, in eastern Washington.

    The findings are reported in the March 7 issue of Science Express by a team of scientists from NASA, the Smithsonian Institution in Washington, and the Southwest Research Institute in Boulder, Colo"

    All of the HiRISE images are archived here.

    More information about the MRO mission is available online.

    Mars Odyssey Orbiter - March 20, 2013
    Sun in the Way Will Affect Mars Missions in April

    "PASADENA, Calif. - The positions of the planets next month will mean diminished communications between Earth and NASA's spacecraft at Mars.

    Mars will be passing almost directly behind the sun, from Earth's perspective. The sun can easily disrupt radio transmissions between the two planets during that near-alignment. To prevent an impaired command from reaching an orbiter or rover, mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., are preparing to suspend sending any commands to spacecraft at Mars for weeks in April. Transmissions from Mars to Earth will also be reduced.

    The travels of Earth and Mars around the sun set up this arrangement, called a Mars solar conjunction, about once every 26 months.

    "This is our sixth conjunction for Odyssey," said Chris Potts of JPL, mission manager for NASA's Mars Odyssey, which has been orbiting Mars since 2001. "We have plenty of useful experience dealing with them, though each conjunction is a little different."

    The Mars solar conjunctions that occur once about every 26 months are not identical to each other. They can differ in exactly how close to directly behind the sun Mars gets, and they can differ in how active the sun is. The sun's activity, in terms of sunspots and solar flares, varies on a 22-year cycle."

    Global Martian Map

    "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 THEMIS."

    Daily Mars Odyssey THEMIS Images
    Can be found at the Thermal Emission Imaging System (THEMIS) website.

    The Odyssey data are available through a new online access system established by the Planetary Data System.

    Visit the Mars Odyssey Mission page.

    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!

    More Acknowledgements and References

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