Astronomy News for the Month of April 2015


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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.


22

The Moon

Phases

Apogee/Perigee

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 as well as meteor shower radiants are also included in the reports. These reports have been optimized for the Denver, Colorado location, however, the times will be approximate for other locations on Earth.

(All times are local unless otherwise noted.)

Planetary Highlights for April

Venus, Jupiter and Saturn put on great planetary shows this month. Venus dominates the early evening sky soon after sunset. Jupiter dominates the night sky and Saturn dominates the early morning sky. However, there are two events that are dependent on the weather this month. The first is the total lunar eclipse when the Moon passes through the Earth's shadow on the morning of the 4th. The second is the Lyrid meteor shower occurring on the night of the 22/23. This is the first meteor shower of 2015 that the Moon will not interfere with observing.

Mercury

Is in superior conjunction on the 9th. Mercury rises at 6:34 a.m. on the 1st. Mercury sets about 9:41 p.m. by month's end. Look for Mercury low to the west about 30 minutes after sunset during the last two of weeks of April. Mercury moves from the constellation of Pisces into Taurus shining at magnitude -0.5 on the 30th.

Venus

Sets at 10:30 p.m. on the 1st and about 11:30 p.m. by month's end. Look for Venus fairly high above the western horizon soon after sunset. On the evening of the 10th, look for Venus passing about 3° south of the Pleiades star cluster. Venus moves from the constellation Aries into Taurus shining at magnitude -4.1.

Earth

N/A.

Mars

Sets at 8:58 p.m. on the 1st and about 8:51 p.m. by month's end. Mars can be spotted well below Venus this month rapidly approaching the western horizon. Mars is in the constellation of Aries this month shining at magnitude 1.4.

Jupiter

Is stationary on the 8th. Sets at 4:29 a.m. on the 1st and about 2:33 a.m. by month's end. Jupiter is visible almost all night long. Look for Jupiter high in the sky just east of zenith soon after sunset. Jupiter is in the constellation of Cancer shining at magnitude -2.2.

Saturn

Rises at 11:34 p.m. on the 1st and about 9:29 p.m. by month's end. Look for Saturn in the late evening and after midnight this month. Saturn is in the constellation of Scorpius shining at magnitude 0.2.

Uranus

Is in conjunction with the Sun on the 6th. Sets at 7:42 p.m. on the 1st. Uranus rises about 5:06 a.m. by month's end. Uranus returns to the morning sky after about mid-month but is still lost in the twilight glow until month's end. Uranus is in the constellation of Pisces shining at magnitude 5.9.

Neptune

Rises at 5:31 a.m. on the 1st and about 3:35 a.m. by month's end. Look for Neptune low to the east in the morning sky. Neptune is in the constellation of Aquarius shining at magnitude 7.9.

Dwarf Planets

Ceres

Rises at 4:53 a.m. on the 1st and about 3:25 a.m. by month's end. Ceres will be difficult to spot to the southeast before sunrise. Ceres is in the constellation of Capricornus shining at magnitude 9.0.

Pluto

Is stationary on the 17th. Pluto rises at 2:36 a.m. on the 1st and about 12:38 a.m. by month's end. Pluto is in the constellation of Sagittarius shining at magnitude 14.2.

As always, good luck at spotting Neptune, Ceres and Pluto, a large telescope and dark skies will be needed.

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Astronomical Events

Meteor Showers

  • The Lyrids [meteor shower] 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 Meteor Showers, visit Gary Kronk's Meteor Showers Online web page.

  • Comets

  • Comet Lovejoy (C/2014 Q2) is continuing its northward journey through the constellation of Cassiopeia this month making it visible for northern observers all night long. Shining around 10th magnitude, Comet Lovejoy will still be difficult to spot unless observed from dark sky sites.

  • 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 Cometography.com webpage.

  • Lunar Eclipse

  • A total lunar eclipse occurs on the morning of the 4th at 8:06 a.m. EDT. The farther west you live the better view of the eclipse observers will have. Partial eclipse begins at 6:16 a.m. EDT (3:16 a.m. PDT and totality at 4:48 a.m. PDT).

    Credit: http://shadowandsubstance.com

  • Observational Opportunities

  • Look for Venus and Mars to the west soon after sunset.
  • Observe Jupiter almost all night long.
  • Observe Saturn in the early morning sky before sunrise.
  • Enjoy the Lyrids on the moonless evenings around the 22nd.
  • Try to spot Comet Lovejoy with a small telescope or binoculars.
  • Asteroids

    (From west to east)
    • Juno is in the constellation of Cancer.
    • Iris is in the constellation of Sextans.
    • Nysa is in the constellation of Virgo.
    • Massalia is at opposition on the 20th in the constellation of Virgo.
    • Herculina is in the constellation of Ophiuchus.
    • Pallas is stationary on the 19th in the constellation of Ophiuchus.

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

    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 30, 2015
    Saturn Spacecraft Returns to the Realm of Icy Moons

    Full image and caption

    "A dual view of Saturn's icy moon Rhea marks the return of NASA's Cassini spacecraft to the realm of the planet's icy satellites. This follows nearly two years during which the spacecraft's orbits carried it high above the planet's poles. Those paths limited the mission's ability to encounter the moons, apart from regular flybys of Titan.

    The new image is available at:

    http://www.jpl.nasa.gov/spaceimages/details.php?id=pia19057

    Cassini's orbit will remain nearly equatorial for the remainder of 2015, during which the spacecraft will have four close encounters with Titan, two with Dione and three with the geyser-moon, Enceladus.

    The two views of Rhea were taken about an hour-and-a-half apart on Feb. 9, 2015, when Cassini was about 30,000 to 50,000 miles (50,000 to 80,000 kilometers) away from the moon. Cassini officially began its new set of equatorial orbits on March 16.

    The views show an expanded range of colors from those visible to human eyes in order to highlight subtle color variations across Rhea's surface. In natural color, the moon's surface is fairly uniform. The image at right represents the highest-resolution color view of Rhea released to date."

    The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. More information about Cassini is available at the following sites:
    http://www.nasa.gov/cassini
    http://saturn.jpl.nasa.gov "

    Raw images are available at http://saturn.jpl.nasa.gov/photos/raw/index.cfm.

    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 - March 27, 2015
    New Horizons Sampling 'Space Weather' on Approach to Pluto

    "As NASA's New Horizons spacecraft approaches the Pluto system, its space plasma (also called charged particle) instruments - SWAP and PEPSSI - have already been taking measurements and assessing the space weather environment in the Kuiper Belt near Pluto.

    "Results from those measurements are being radioed to the ground and our team is already learning new things about the distant environment near Pluto's orbit, 3 billion miles from Earth," says New Horizons Principal Investigator Alan Stern, from Southwest Research Institute, Boulder, Colo.

    The solar wind consists mainly of protons and electrons, but also has trace amounts of ions of helium and oxygen that New Horizons detects. Typical solar wind speeds at Pluto's orbit distance range from 350-500 kilometers per second (about 750,000-1 million miles per hour); typical densities of the solar wind near Pluto's orbit are about 6,000 particles per cubic meter - about a 1,000 times less than the solar wind at Earth. For comparison, the Earth's atmosphere at its surface is one hundred billion-billion times denser."

    What is Pluto?

    On Video: How Do We Get to Pluto? Practice, Practice, Practice

    Part I: The Encounter Begins
        - Small mp4 (38 MB, 640x360)
        - Large mp4 (116 MB, 1280x720)

    Part II: Passing Pluto
        - Small mp4 (34 MB, 640x360)
        - Large mp4 (102 MB, 1280x720)"

    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 - March 06, 2015
    NASA Spacecraft Becomes First to Orbit a Dwarf Planet

    Full image and caption

    "NASA's Dawn spacecraft has become the first mission to achieve orbit around a dwarf planet. The spacecraft was approximately 38,000 miles (61,000 kilometers) from Ceres when it was captured by the dwarf planet’s gravity at about 4:39 a.m. PST (7:39 a.m. EST) Friday.

    Mission controllers at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California received a signal from the spacecraft at 5:36 a.m. PST (8:36 a.m. EST) that Dawn was healthy and thrusting with its ion engine, the indicator Dawn had entered orbit as planned.

    "Since its discovery in 1801, Ceres was known as a planet, then an asteroid and later a dwarf planet," said Marc Rayman, Dawn chief engineer and mission director at JPL. "Now, after a journey of 3.1 billion miles (4.9 billion kilometers) and 7.5 years, Dawn calls Ceres, home."

    In addition to being the first spacecraft to visit a dwarf planet, Dawn also has the distinction of being the first mission to orbit two extraterrestrial targets. From 2011 to 2012, the spacecraft explored the giant asteroid Vesta, delivering new insights and thousands of images from that distant world. Ceres and Vesta are the two most massive residents of our solar system’s main asteroid belt between Mars and Jupiter."

    Ion propulsion isn't something found only in science fiction. Ion engines are a real deal and drive NASA's Dawn spacecraft, en route to dwarf planet Ceres. Big things do come in small packages.

    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 27, 2015
    MESSENGER Completes 4,000th Orbit of Mercury

    "On March 25, the MESSENGER spacecraft completed its 4,000th orbit of Mercury, and the lowest point in its orbit continues to move closer to the planet than ever before. The orbital phase of the MESSENGER mission, which was originally designed to collect data for one Earth year, just completed its fourth year of operation around Mercury. The mission has received a final extension to allow scientists to gather specific low-altitude data over an additional several weeks.

    "When we completed our first Mercury flyby on January 14, 2008, after months of preparations and testing, we were amazed and perhaps even a little skeptical when the science team told us that the orbital phase could be characterized as two flybys of data collection every Earth day (and eventually three per day starting in April 2012)," said MESSENGER Mission Operations Manager Andy Calloway, of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. "Now that we have surpassed 4,000 orbits and more than 17 Mercury years since Mercury orbit insertion, we know just what was meant by that prediction.'"

    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 - http://www.jpl.nasa.gov/missions

    Visit JPL's mission pages for current status.

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    Mars Missions

    Be A Martian

    Mars website mobile version is here!

    Mars on the Go! NASA Be A Martian Mobile App
    If you want the latest news as it happens, try our Be A Martian app.
    Download on Mobile Devices
    Android | iPhone | Windows Phone
    JMARS

    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.

     

    Laboratory for Atmospheric and Space Physics

    "The Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder (CU) began in 1948, a decade before NASA. We are the world's only research institute to have sent instruments to all eight planets and Pluto. LASP is an affiliate of CU-Boulder AeroSpace Ventures, a collaboration among aerospace-related departments, institutes, centers, government labs, and industry partners."

    MAVEN Status Update: March 18, 2015
    MAVEN Detects Aurora and Mysterious Dust Cloud around Mars

    "The MAVEN spacecraft has observed two unexpected phenomena in the Martian atmosphere: an unexplained high-altitude dust cloud and aurora that reaches deep into the Martian atmosphere.

    The presence of the dust at orbital altitudes from about 93 miles (150 kilometers) to 190 miles (300 kilometers) above the surface was not predicted. Although the source and composition of the dust are unknown, there is no hazard to MAVEN and other spacecraft orbiting Mars.

    "If the dust originates from the atmosphere, this suggests we are missing some fundamental process in the Martian atmosphere," said Laila Andersson of the University of Colorado’s Laboratory for Atmospherics and Space Physics (CU/LASP)."

    Visit LASP and MAVEN for more information.

    Mars Science Laboratory - Curiosity - March 27, 2015

    Scars on Mars from 2012 Rover Landing Fade -- Usually
    Full image and caption

    "A series of observations from Mars orbit show how dark blast zones that were created during the August 2012 landing of NASA's Curiosity rover have faded inconsistently.

    The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter made the observations on multiple dates from landing to last month. After fading for about two years, the pace of change slowed and some of the scars may have even darkened again.

    The images track changes in blast zones at four locations caused by different pieces of Curiosity hardware, such as the heat shield and the descent stage. The four series, each with images from five to seven different dates since landing."

    To follow the Mars Curiosity rover and NASA on Foursquare, visit: http://www.foursquare.com/MarsCuriosity and http://www.foursquare.com/NASA

    For information about NASA's partnership with Foursquare, visit:http://www.nasa.gov/connect/foursquare.html.

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

      Visit the Mars Science Laboratory page.

    Mars Exploration Rover Mission (Spirit and Opportunity) - March 24, 2015

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

    "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)."

    OPPURTUNITY UPDATE: Flash Reformatted and Marathon Completed - sols 3963-3969, March 18, 2015-March 24, 2015: :

    "The Opportunity mission is now the first human enterprise to exceed marathon distance of travel on another world.

    Opportunity is on the west rim of Endeavour Crater near 'Marathon Valley', a putative location for abundant clay minerals. The rover is approaching a feature called 'Spirit of St. Louis Crater' at the entrance to Marathon Valley.

    On Sol 3964 (March 19, 2015), the flash-memory file system was reformatted using new flight software. The reformat was successful. The rover is again using flash for nonvolatile data storage. On Sol 3966 (March 21, 2015), Opportunity began approaching the Spirit of St. Louis Crater with a 177-foot (54-meter) drive, avoiding some obstacles along the way. The drive was preceded with some targeted Pancam imagery and followed by a Navcam panorama, which is typical practice when driving.

    On Sol 3968 (overnight March 23 to March 24), Opportunity made history. The rover the rover drove 154 feet (46.9 meters) in a dog leg around the crater. With that drive, Opportunity exceeded the distance for a marathon (26.219 miles or 42.195 kilometers). On Sol 3959 (March 24), the rover continued to advance with a 28-foot (8.5-meter) approach to a light-toned rock outcrop.

    As of Sol 3969, the solar array energy production was 610 watt-hours with an atmospheric opacity (Tau) of 0.678 and a solar array dust factor of 0.717.

    Total odometry as of Sol 3969 (March 24, 2015) is 26.241 mile (42.230 kilometers)."

    Landing sites

    Visit the Mars Exploration Rover page.

    Mars Reconnaissance Orbiter Mission - February 09, 2014
    NASA Spacecraft Completes 40,000 Mars Orbits

    Full image and caption

    -- NASA's Mars Reconnaissance Orbiter, at Mars since 2006, has now orbited the Red Planet more than 40,000 times

    -- The continuing mission studies the whole planet and has shown that Mars is diverse and dynamic

    "NASA's Mars Reconnaissance Orbiter passed a mission milestone of 40,000 orbits on Feb. 7, 2015, in its ninth year of returning information about the atmosphere, surface and subsurface of Mars, from equatorial to polar latitudes.

    The mission's potent science instruments and extended lifespan have revealed that Mars is a world more dynamic and diverse than was previously realized. Now in its fourth mission extension after a two-year prime mission, the orbiter is investigating seasonal and longer-term changes, including some warm-season flows that are the strongest evidence so far for liquid water on Mars today.

    The orbiter has returned 247 terabits of data, which is more than the combined total from every other mission that has ever departed Earth to visit another planet."

    Simulated Flyover of Mars Canyon Map

    This animation simulates a flyover of a portion of a Martian canyon detailed in a geological map produced by the U.S. Geological Survey and based on observations by the HiRISE camera on NASA's Mars Reconnaissance Orbiter. The landforms include a series of hills called Candor Colles.

    MARS RECONNAISSANCE ORBITER HIRISE IMAGES
    All of the HiRISE images are archived here.

    More information about the MRO mission is available online.

    Mars Odyssey Orbiter - December 02, 2014
    NASA's Journey to Mars

    "NASA is developing the capabilities needed to send humans to an asteroid by 2025 and Mars in the 2030s - goals outlined in the bipartisan NASA Authorization Act of 2010 and in the U.S. National Space Policy, also issued in 2010.

    Mars is a rich destination for scientific discovery and robotic and human exploration as we expand our presence into the solar system. Its formation and evolution are comparable to Earth, helping us learn more about our own planet's history and future. Mars had conditions suitable for life in its past. Future exploration could uncover evidence of life, answering one of the fundamental mysteries of the cosmos: Does life exist beyond Earth?

    While robotic explorers have studied Mars for more than 40 years, NASA's path for the human exploration of Mars begins in low-Earth orbit aboard the International Space Station. Astronauts on the orbiting laboratory are helping us prove many of the technologies and communications systems needed for human missions to deep space, including Mars. The space station also advances our understanding of how the body changes in space and how to protect astronaut health.

    Our next step is deep space, where NASA will send a robotic mission to capture and redirect an asteroid to orbit the moon. Astronauts aboard the Orion spacecraft will explore the asteroid in the 2020s, returning to Earth with samples. This experience in human spaceflight beyond low-Earth orbit will help NASA test new systems and capabilities, such as Solar Electric Propulsion, which we'll need to send cargo as part of human missions to Mars. Beginning in FY 2018, NASA's powerful Space Launch System rocket will enable these "proving ground" missions to test new capabilities. Human missions to Mars will rely on Orion and an evolved version of SLS that will be the most powerful launch vehicle ever flown."

    See the Mars As Art Gallery

    Dulles Airport Full News Release

    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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    Astronomy Links and Other Space News

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

    Green Laser

    Colorado Astronomy Links

    Other Astronomy Links

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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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