[astronews] IAAS Monthly Astronomy Newsletter

  • From: Burness Ansell <ki0ar@xxxxxxxxx>
  • To: Astronomy Newsletter <astronews@xxxxxxxxxxxxx>
  • Date: Fri, 1 Apr 2011 19:59:32 -0700 (PDT)

IAAS Monthly Astronomy Newsletter
April 2011

The International Association for Astronomical Studies provides this newsletter 
as a service for interested persons worldwide.

This newsletter is published on the World Wide Web at 
http://www.ki0ar.com/astro.html - The Home of KI0AR - and is received 
nationally and internationally. A PDF formatted downloadable version of the 
newsletter is at http://www.ki0ar.com/current_nl.pdf.

This newsletter is now available as an iTunes podcast. Visit 
http://www.apple.com, download and install iTunes (for either Mac or Windows). 
Search for "IAAS" and subscribe to the podcast. You may also go to 
http://www.ki0ar.com/astro.html and click on the Subscribe/RSS link. Update 
your iPod or mp3 player and listen to the newsletter at your leisure. Since 
this is a new feature, comments and constructive criticisms are greatly 

An Open Invitation - For amateur radio operators and scanner enthusiasts, when 
in the Denver metro area, please join the Colorado Astronomy Net on the Rocky 
Mountain Radio League's (http://rmrl.hamradios.com/) 146.94 MHz repeater on 
Tuesday nights at 7 P.M. 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.

In This Newsletter...

* The Moon
* The Planets
* Astronomical Events
* Planetary/Lunar Exploration Missions
* Web Sites of Interest
* Acknowledgments and References
* Subscription Information

The Month At-A-Glance at http://www.ki0ar.com/ataglance.html
A calendar displaying the daily astronomical events.

The Moon

* New Moon occurs on the 3rd.
* First Quarter Moon occurs on the 11th.
* Full Moon occurs on the 17th.
* Last Quarter Moon occurs on the 24th.

* The Moon is at Apogee on the 2nd, 252,684 miles from Earth.
* The Moon is at Perigee on the 17th, 222,507 miles from Earth.
* The Moon is at Apogee on the 29th, 252,301 miles from Earth.

Moon/Planet Pairs:
* The Moon passes 8° south of Saturn on the 17th.
* Mercury passes 0.8° north of Mars on the 19th.
* Venus passes 0.9° south of Uranus on the 22nd.
* The Moon passes 6° north of Neptune on the 27th.
* The Moon passes 6° north of Uranus on the 29th.
* The Moon passes 7° north of Venus on the 30th.

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

The Planets & Dwarf Planets
Planetary Reports are generated by "TheSky" software. 
(http://www.ki0ar.com/planrpts.html) These reports provide predicted data for 
the planets on 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. 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 - Saturn rules the evening skies this month. 
Saturn reaches opposition and is at its best viewing this month. Venus is 
prominent in the early morning sky before sunrise. However, you will have to 
wait until the end of the month to see the other visible planets, Mercury, Mars 
and Jupiter, although Mercury and Mars will be much more difficult to spot than 

* Mercury - Is in inferior conjunction on the 9th. Mercury is stationary on the 
22nd. Mercury will return to the morning sky at the end of this month. Mercury 
rises at 5:09 a.m. by the end of the month. When visible, Mercury is in the  
constellation of Pisces shining at magnitude 0.9.

* Venus - Rises at 4:26 a.m. on the 1st and about 4:57 a.m. by month's end. 
Venus shines brightly in the morning sky before sunrise. Venus moves from the 
constellation of Aquarius into Pisces this month shining at magnitude -3.9.

* Earth - N/A.

* Mars - Returns to the morning sky late this month but may not be visible 
through the morning twilight glow. Mars rises around 5:18 a.m. by the end of 
the month, shining at magnitude 1.2 in the constellation of Pisces.

* Jupiter - Is in conjunction with the Sun on the 6th. Jupiter returns to the 
morning sky in late April. Jupiter rises about 5:19 a.m. by month's end. 
Jupiter is in the constellation of Pisces this month shining at magnitude -2.1.

* Saturn - Is at opposition on the 3rd, rising as the Sun sets. Saturn rises at 
6:22 p.m. on the 1st and about 5:15 p.m. by month's end. Saturn is the dominant 
evening planet this month and will remain so for several more months. Saturn is 
in the constellation of Virgo shining at magnitude 0.4.

* Uranus - Rises at 5:24 a.m. on the 1st and about 4:30 a.m. by month's end. 
Although Uranus has returned to the morning sky, Uranus will be difficult to 
spot through the early morning twilight glow. Uranus is in the constellation of 
Pisces shining at magnitude 5.9.

* Neptune - Rises at 4:08 a.m. on the 1st and about 3:12 a.m. by month's end.  
Neptune is in the constellation of Aquarius shining at magnitude 8.0.

Dwarf Planets  
* Ceres - Rises at 5:53 a.m. on the 1st and about 4:24 a.m. by month's end. 
Ceres is in the constellation of Aquarius this month shining at magnitude 9.3.

* Pluto - Is stationary on the 9th. Pluto rises at 12:55 a.m. on the 1st and 
about 11:53 p.m. by month's end. Pluto is in the constellation of Sagittarius 
shining at magnitude 14.0.

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

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 Meteor Showers, visit Gary Kronk's Meteor Showers 
Online web page at http://meteorshowersonline.com/.

* There is no significant comet activity this 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, visit Gary Kronk's Cometography.com web 
page at http://cometography.com/.

* There is no eclipse activity this month.

Observational Opportunities
* Saturn is at its best this month when it reaches opposition on the 3rd.
* On the morning of the 30th look for a crescent Moon along with Venus, Mars, 
Jupiter and Mercury low in the east before sunrise, though you may need a good 
pair of binoculars or a small telescope to spot Mars and Mercury in the 
twilight glow.

Asteroids (From west to east)
* Iris is in the constellation of Cancer.
* Juno is stationary on the 29th in the constellation of Leo.
* Massalia is in the constellation of Leo.
* Hygiea is in the constellation of Libra.
* Vesta is in the constellation of Capricornus.
* Nysa is in the constellation of Leo.

* Information about the Minor Planets can be found at 
http://www.minorplanetobserver.com the Minor Planet Observer web site.

* Information on various occultations can be found at 
http://lunar-occultations.com/iota/iotandx.htm , the International Occultation 
Timing Association's (IOTA) web site.
Planetary/Lunar Exploration Missions
(Excerpts from recent mission updates)

* Cassini - March 31, 2011
Forensic Sleuthing Ties Ring Ripples to Impacts

"PASADENA, Calif. - Like forensic scientists examining fingerprints at a cosmic 
crime scene, scientists working with data from NASA's Cassini, Galileo and New 
Horizons missions have traced telltale ripples in the rings of Saturn and 
Jupiter back to collisions with cometary fragments dating back more than 10 
years ago.

The ripple-producing culprit, in the case of Jupiter, was comet Shoemaker-Levy 
9, whose debris cloud hurtled through the thin Jupiter ring system during a 
kamikaze course into the planet in July 1994. Scientists attribute Saturn's 
ripples to a similar object - likely another cloud of comet debris -- plunging 
through the inner rings in the second half of 1983. The findings are detailed 
in a pair of papers published online today in the journal Science.

"What's cool is we're finding evidence that a planet's rings can be affected by 
specific, traceable events that happened in the last 30 years, rather than a 
hundred million years ago," said Matthew Hedman, a Cassini imaging team 
associate, lead author of one of the papers, and a research associate at 
Cornell University, Ithaca, N.Y. "The solar system is a much more dynamic place 
than we gave it credit for."

Cassini Imaging Team's website - http://ciclops.org.

For the latest mission status reports, visit 
http://saturn.jpl.nasa.gov/home/index.cfm. The speed and location of the 
spacecraft can be viewed on the "Present Position" web page.

* New Horizons - March 18, 2011
Later, Uranus: New Horizons Passes Another Planetary Milestone

"New Horizons is ready to put another planet - or at least the planet's orbit - 
in its rearview mirror. The Pluto-bound spacecraft crosses the path of Uranus 
around 6 p.m. EDT on March 18, more than 1.8 billion miles from Earth.

"New Horizons is all about delayed gratification, and our 9 1/2-year cruise to  
the Pluto system illustrates that," says Principal Investigator Alan Stern, of 
the Southwest Research Institute.  "Crossing the orbit of Uranus is another 
milepost along our long journey to the very frontier of exploration."

New Horizons is headed for a rendezvous with planet Pluto and its three moons 
in July 2015 and, soon after, possible encounters with smaller bodies in the 
distant Kuiper Belt. The fastest spacecraft ever launched, New Horizons has 
already covered serious space since lifting off in January 2006 — traversing 20 
times the distance between Earth and the sun, including a flight through the 
Jupiter system in 2007 for a gravity-assisted speed boost and scientific 
observations of the giant planet and its largest moons."

New Horizons gallery http://pluto.jhuapl.edu/gallery/sciencePhotos/.

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

* Dawn - March 29, 2011
When is an Asteroid Not an Asteroid?

"On March 29, 1807, German astronomer Heinrich Wilhelm Olbers spotted Vesta as 
a pinprick of light in the sky. Two hundred and four years later, as NASA's 
Dawn spacecraft prepares to begin orbiting this intriguing world, scientists 
now know how special this world is, even if there has been some debate on how 
to classify it.

Vesta is most commonly called an asteroid because it lies in the orbiting 
rubble patch known as the main asteroid belt between Mars and Jupiter. But the 
vast majority of objects in the main belt are lightweights, 100-kilometers-wide 
(about 60-miles wide) or smaller, compared with Vesta, which is about 530 
kilometers (330 miles) across on average. In fact, numerous bits of Vesta 
ejected by collisions with other objects have been identified in the main belt.

"I don't think Vesta should be called an asteroid," said Tom McCord, a Dawn 
co-investigator based at the Bear Fight Institute, Winthrop, Wash. "Not only is 
Vesta so much larger, but it's an evolved object, unlike most things we call 

The layered structure of Vesta (core, mantle and crust) is the key trait that 
makes Vesta more like planets such as Earth, Venus and Mars than the other 
asteroids, McCord said. Like the planets, Vesta had sufficient radioactive 
material inside when it coalesced, releasing heat that melted rock and enabled 
lighter layers to float to the outside. Scientists call this process 

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

* MESSENGER - March 29, 2011
MESSENGER Sends Back First Image of Mercury from Orbit

"MESSENGER has delivered its first image 
 since entering orbit about Mercury on March 17. It was taken today at 5:20 am 
EDT by the Mercury Dual Imaging System as the spacecraft sailed high above 
Mercury's south pole, and provides a glimpse of portions of Mercury's surface 
not previously seen by spacecraft. The image was acquired as part of the 
orbital commissioning phase of the MESSENGER mission. Continuous global mapping 
of Mercury will begin on April 4."

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.
+ http://virtualfieldtrip.jpl.nasa.gov/ ;
* Past, Present, Future and Proposed JPL Missions - 

* For special JPL programs and presentations in your area visit the JPL Solar 
System Ambassador web site at http://www2.jpl.nasa.gov/ambassador/index.html.

Mars Missions

* Mars Odyssey Orbiter - No new news since December 15, 2010
NASA's Odyssey Spacecraft Sets Exploration Record on Mars

"PASADENA, Calif., -- NASA's Mars Odyssey, which launched in 2001, will break 
the record Wednesday for longest-serving spacecraft at the Red Planet. The 
probe begins its 3,340th day in Martian orbit at 5:55 p.m. PST (8:55 p.m. EST) 
on Wednesday to break the record set by NASA's Mars Global Surveyor, which 
orbited Mars from 1997 to 2006.

Odyssey's longevity enables continued science, including the monitoring of 
seasonal changes on Mars from year to year and the most detailed maps ever made 
of most of the planet. In 2002, the spacecraft detected hydrogen just below the 
surface throughout Mars' high-latitude regions. The deduction that the hydrogen 
is in frozen water prompted NASA's Phoenix Mars Lander mission, which confirmed 
the theory in 2008. Odyssey also carried the first experiment sent to Mars 
specifically to prepare for human missions, and found radiation levels around 
the planet from solar flares and cosmic rays are two to three times higher than 
around Earth."

Global Martian Map: http://www.mars.asu.edu/maps/?layer=thm_dayir_100m_v11.

"A simulated fly-through using the newly assembled imagery is available online 
at http://www.nasa.gov/mission_pages/mars/missions/odyssey/20060313.html.

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

Thermal Emission Imaging System (THEMIS) web site: 

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 at 

* Mars Exploration Rover Mission (Spirit and Opportunity) - March 30, 2011

SPIRIT UPDATE: Spirit Remains Silent at Troy - sols 2567-2573, March 24-30, 

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

Deep Space Network X-band listening and recovery commanding continue. The 
project has been systematically conducting commanding over a range of 
frequencies and over a range of local solar times on Mars. This covers the 
possibility that the rover's receiver has degraded and/or the clock has drifted 
significantly since March of 2010.

The project is continuing the commanding of extra-long ultra-high frequency 
(UHF) relay passes to account for possible rover clock drift or clock error and 
to make the rover responsive to UHF relay (if it is has experienced a 
mission-clock fault). The team is also commanding the backup solid-state power 
amplifier, in case the primary X-band transmitter has failed.

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

OPPORTUNITY UPDATE: Opportunity Completes Several Drives This Week - sols 
2546-2553, March 23-30, 2011:

"Opportunity has resumed the trek towards Endeavour crater with a series of 

On Sol 2547 (March 24, 2011), the rover drove over 100 meters (328 feet) due 
east away from Santa Maria crater and toward Endeavour. On the next sol, 
Opportunity completed another long drive of over 114 meters (374 feet), but 
this time to the south to avoid some boulder-strewn terrain. On Sol 2551 (March 
28, 2011), the rover continued in a south-southeast direction with a 71-meter 
(233 foot) drive to avoid more difficult terrain. Opportunity drove again on 
Sol 2552 (March 29, 2011), with a 39-meter (128-foot) drive, crossing another 
odometry mark. Opportunity has now driven over 27 kilometers (almost 17 miles) 
on Mars!

There has been a small increase in the motor currents for the right-front 
wheel. The project is keeping a close eye on this. A diagnostic of the 
miniature thermal emission spectrometer (Mini-TES) instrument was performed on 
Sol 2550 (March 27, 2011). The result of these tests still indicates anomalous 
behavior. More testing is planned. As of Sol 2552 (March 29, 2011), solar array 
energy production was 423 watt-hours with an elevated atmospheric opacity (Tau) 
of 0.914 and a solar array dust factor of 0.560.

Total odometry is 27,035.63 meters (27 kilometers, or 16.80 miles)."

Landing sites link - http://marsoweb.nas.nasa.gov/landingsites/ ;

Visit the Mars Exploration Rover page at

* Mars Reconnaissance Orbiter Mission - March 09, 2011
Prolific NASA Orbiter Reaches Five-Year Mark

"PASADENA, Calif. -- NASA's versatile Mars Reconnaissance Orbiter, which began 
orbiting Mars five years ago on March 10, has radically expanded our knowledge 
of the Red Planet and is now working overtime.

The mission has provided copious information about ancient environments, 
ice-age-scale climate cycles and present-day changes on Mars.

The orbiter observes Mars' surface, subsurface and atmosphere in unprecedented 
detail. The spacecraft's large solar panels and dish antenna have enabled it to 
transmit more data to Earth -- 131 terabits and counting, including more than 
70,000 images -- than all other interplanetary missions combined. Yet many 
things had to go well for the mission to achieve these milestones."


All of the HiRISE images are archived here:

More information about the MRO mission is available online at 

* 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: 
http://mars.jpl.nasa.gov/missions/ and the Mars Exploration page: 

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

* Astronomy A-Go-Go - http://astronomy.libsyn.com/
In the car, at work or under the night time sky astronomy goes where you go! 
(This page has not been updated since September 2010)

* "TheSky" Software - http://www.bisque.com ;

* A Short Guide to Celestial Navigation - http://www.celnav.de/ ;

* Astrogirl Homepage - http://www.astrogirl.org ;

* Astronomical Lexicon - http://www.ki0ar.com/astrolex.html ;
Many of the astronomical terms used in this newsletter are defined here.

* Astronomy Picture of the Day - http://antwrp.gsfc.nasa.gov/apod/astropix.html ;

* Black Hole Encyclopedia - http://blackholes.stardate.org/ Excellent site from 
StarDate - University of Texas McDonald Observatory 

* Celestron Telescopes - http://www.celestron.com/c2/index.php - New beta 

* Cloudbait Observatory, Guffey Colorado - http://www.cloudbait.com - Submit 
your fireball reports here. Interesting, knowledgeable site.

* The Constellations and Their Stars - 
http://www.astro.wisc.edu/~dolan/constellations/constellations.html ;
Good site for finding out more about the 88 constellations and their associated 

* Denver Astronomical Society - http://www.denverastrosociety.org ;

* Distant Suns - http://www.distantsuns.com/ ;
Desktop Astronomy package for PCs.

* Eric's Black Sun Eclipse website -
http://www.ericsblacksuneclipse.com ;

* Green Laser - http://www.greenlaser.com
If you're looking for a reasonably priced laser pointer that is great for 
astronomy work, visit this site.

* Groovy Adventures - http://www.groovyadventures.com ;
Unique adventures and vacations including astronomy related vacations.

* The International Dark-Sky Association - http://www.darksky.org
To preserve and protect the nighttime environment and our heritage of dark 

* JPL Solar System Ambassador Program -

* JPL Solar System - http://www.jpl.nasa.gov/solar_system/ ;

* Meade Advanced Products Users Group - http://www.mapug-astronomy.net/ - 
Mapug-Astronomy Topical Archive & information resource, containing a massive 
335 page archive of discussions about Meade equipment, and much more: 
observatories, observing lists, permanent piers, equatorial wedges, remote 
operations, software, eyepieces, etc.

* My Stars Live - http://www.mystarslive.com/ ;
Interactive Star Chart

* NASA Science News - http://science.nasa.gov/ ;

* Northern Colorado Astronomical Society - http://ncastro.org/ ;

* Sangre Stargazers - http://sangrestargazers.skymtn.com/ - New astronomy club 
in the Wet Mountain Valley of Custer County (about 45 miles due west of Pueblo, 

* Sky and Space - http://www.skyandspace.com.au/public/home.ehtml ;
Astronomy from Down Under - The Southern Hemisphere's first astronomy and space 

* Skymaps.com - http://www.skymaps.com/

* Skywatch Sightings from NASA - 
http://spaceflight.nasa.gov/realdata/sightings/ ;
This site gives you the best times to watch the ISS pass over or near your 

* Southern Colorado Astronomical Society - http://www.scasastronomy.info/

* Space.com - http://space.com ;
Interesting space and astronomy articles.

* Space.com - Sky Watch Calendar -
http://www.space.com/spacewatch/sky_calendar.html ;

* Spaceflight Now - http://spaceflightnow.com/ ;

* "SpaceRef.com" - http://www.spaceref.com/ - SpaceRef's 21 news and reference 
web sites are designed to allow both the novice and specialist alike to explore 
outer space and Earth observation.
This site includes links to planetary updates such as Mercury Today, Venus 
Today, Earth Today, Moon Today, Mars Today, Jupiter Today, Saturn Today, Pluto 
Today, etc.

* Stellarium - http://www.stellarium.org
Free, downloadable planetarium/astronomy software.

* Universe Today - http://www.universetoday.com

* Wikisky - http://www.wikisky.org
WIKISKY is a non-commercial project. The main purpose of WIKISKY is to 
consolidate astronomical, astrophysical and other information about different 
space objects and astrophysical facts.

Acknowledgments and References

Much of the information in this newsletter is from "Astronomy Magazine" 
(Kalmbach Publishing), JPL mission status reports, "Meteor Showers - A 
Descriptive Catalog" by Gary W. Kronk and other astronomical sources that I 
have stashed on my book shelves.

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 KI0AR

Created by Burness F. Ansell, III

COO, Director of Aerospace Technologies, IAAS
JPL Solar System Ambassador, Colorado
Last modified: March 31, 2011

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