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The volume of the Moon is about 21.9 billion cubic kilometers.
Does that sound like a lot? For comparison, the volume of the Earth is 1 trillion cubic kilometers. In other words, the volume of the Moon is only 2% the volume of the Earth.
The interior of the Moon is composed of a crust, mantle and core. Astronomers think that the lunar core is about 350 km across, and accounts for only 20% of the size of the Moon. Most other planets and moons in the Solar System have a core that accounts for about 50% of their diameter. Outside the core is the middle mantle, and this is surrounded by an upper mantle.
Hubble and its most recent science image. Credit: NASA
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The space shuttle mission to repair and update the Hubble Space Telescope has been delayed. Mission managers were aiming for a February 2009 launch for STS-125 flight for the fifth and final shuttle mission to the Hubble Space Telescope. The replacement component for the data handling system that recently caused problems for the telescope not be ready by February, and now NASA is looking for a May 2009 launch. On a positive note, the “other” shuttle mission waiting in the wings, STS-126 to the International Space Station, is looking good and is go for launch. Current launch date is set for November 14 at 7:55 p.m. EST.
“We now have done enough analysis of all the things that need to happen with the flight spare unit to know that we cannot be ready for a February launch,” said NASA’s Astrophysics Division Director Jon Morse at NASA Headquarters in Washington. The spare Science Instrument Command and Data Handling system unit will replace one that failed on Hubble in late September, causing the agency to postpone the servicing mission, which had been targeted for Oct. 14.
A significant anomaly occurred during testing of the unit and NASA says six and a half months of further testing is needed before the it can be certified to fly. NASA’s plan is to have the spare unit ready to ship in the April 2009 timeframe so as to support a May 2009 launch. sts-126 mission. Credit: NASA
Endeavour’s STS-126 flight, set to launch on November 14 will feature important repair work to the station and prepare it for housing six crew members during long-duration missions. The primary focus of the 15-day flight and its four planned spacewalks is to service the station’s two Solar Alpha Rotary Joints, which have not been working correctly. They allow the station’s solar arrays to track the sun. Endeavour will carry about 32,000 pounds to orbit, including supplies and equipment necessary to double the crew size from three to six members in spring 2009. The new station cargo includes additional sleeping quarters, a second toilet and a resistance exercise device.
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Numerous news articles recently have reported problems with the Ares rocket. Some articles detailed critical design flaws, others wondered if Ares was doomed, others reported that Ares was on the US Congress’s “chopping block,” and still others purported that a different launch architecture would be superior to the Ares design. So many rumors were floating around that NASA felt the need to hold a press briefing yesterday to address the rumors and calm any fears that the Constellation program was on the verge of collapse. At the briefing, NASA officials said that while there are some challenges for the program to overcome, Ares is making outstanding progress toward flight. “Some recent news reports about Ares have been inaccurate and draw false conclusions,” said Steve Cook, who leads the development of the rocket.
But isn’t that what everyone expected them to say? Are they telling the truth? To get an unbiased look at the state of the Constellation program, Universe Today contacted Dr. Scott Pace, who is the Director for the Space Policy Institute at George Washington University in Washington, DC. Pace said the problems facing Ares are typical and not insurmountable, and that Constellation is the right choice for our country’s space program. “In my view,” said Dr. Pace, “if the nation is going to return to the Moon and eventually send humans to Mars, then political and technical realities argue that the Ares I, Orion, and Ares V are the way to go.”
Pace said the only reason not to use the Constellation architecture is if our nation decides it is content with staying in low Earth orbit or decides to cease its participation in government sponsored human spaceflight.
Pace discussed some of the issues being debated for the Ares rocket. “From my perspectives, there are a couple of things going on that can be broken down into 1) normal technical issues, 2) system engineering issues, and 3) architecture issues,” said Pace. Dr. Scott Pace. Courtesy Dr. Pace
He said the thrust oscillation issue is a typical issue with all solid propellant motors and there are multiple ways to solve it. “As an analogy,” said Pace, “the pogo issue with Saturn on its first flights was much more serious.”
As for the launch pad drift problems and cross-wind limits on launch, these issues, too, have multiple solutions. “The fast start up of solids compared to liquids means less time to ‘drift,’” said Pace. “However, if a solid goes bad, it goes real bad, and that’s why the abort motor system on the Orion has to be proven to work from the launch pad up to high altitude.”
Pace believes a potentially more serious issue that should be resolved by modeling and test flights are the bending moments of the SRB “stick” itself in flight. “It’s built out of segments, not a single structure and lacks the stiffing of attachment to an External Tank (as with Shuttle and the Ares V design). This is a classic systems engineering problem,” said Pace, and deferred that NASA engineers are more qualified to comment on that issue.
Other issues are criticisms over the architecture choice of Ares I and V, over using an EELV (Evolved Expendable Launch Vehicle) for Orion or the DIRECT 2.0 design of the “Jupiter” rockets. The Jupiter rockets for the DIRECT 2.0 project. Credit: DIRECT 2.0
“The EELVs don’t have the performance to launch a 6-person Orion to ISS or take a 4-man crew to the Moon,” said Pace. “If one built a 3-4 person Orion to go only to ISS, it begs the question of what to do with the other ISS crew in an emergency and creates a potential government competitor for COTS providers.”
Pace said the use of EELV’s also means trying to creating a separate vehicle to provide lift to go to the Moon and Mars. “One could do the Moon with multiple EELV launches (as the Chinese might do with their Long March 5) at additional cost and risk over an Ares I and Ares V launch combination,” said Pace. “But you’re not going to Mars without a heavy-lifter like Ares V.”
Pace continued, “So, if we truly would like to go to Mars, build an Ares V and use it to make going to the Moon efficient. If we’re using an Ares V, separating humans onto a Ares I that shares much of the industrial base with the current Shuttle makes sense. This also allows an Orion capsule that can meet ISS and lunar requirements.”
Pace said EELVs could be useful for cargo to the ISS and, if someone were to pay for man-rating, they may even be useful for COTS crew missions. “But they can’t do the baseline government job of assuring U.S. human access to space.”
To make the Constellation program a success, Pace said NASA will need to focus on configuration control and consistency of analytical models, making sure the avionics interfaces are sufficient and being able to obtain adequate funding of full-scale tests.
* Author’s note: As an addendum, Dr. Pace said he has no problem with adding that he recently worked for NASA’s Program Analysis & Evaluation office, a fact I did not include in the article. “I understand that some may see that as a bias and perhaps relevant,” he said. Dr. Pace was named the Director of SPI in May 2008.
Colored global elevation map based on terrain data from the Kaguya orbiter Credit: Japan Aerospace Exploration Agency (JAXA)
Are you looking for a map of the Moon? As it turns out, there are plenty of resources on the internet that show the Moon’s topography, geology, and map out it’s many interesting surface features – such as craters, volcanoes, and surface rilles. These maps are the result of decade’s worth of satellite and telescopic imaging, lunar landing missions, and even manned missions to the Moon. The exploration is ongoing, and more data pours in with every passing year!
And it just so happens that we’ve compiled a list for your convenience and viewing pleasure. Below are a short collection of websites that provide comprehensive and even interactive maps of the Moon, as well as access to archival images and thousands of pictures of the surface. Click on the links and prepare to do a little exploring of your own!
Observatorio ARVAL – This map of the Moon shows the location of all the seas and major craters on the surface of the Moon.
Google Moon – This is one of the coolest tools you can use to see a lunar map. It has the locations of all the Apollo landing sites.
USGS Moon Maps – The USGS has released a series of topographical maps of the Moon, and various images returned from the Clementine and other missions. If you want data… here’s where you’ll find it.
Albedo Map of the Moon – Here are some maps of the Moon built up with 50,000 images gathered by the Clementine mission.
Maps of the Moon – A collection of mosaic, labelled, and color-coded topographic maps provided by Professor Seligman (BA Astronomy and Physics, MA Astronomy, from UCLA).
Moon-Edu – A resource collection of Moon interactive maps, images and sky-watcher/moon-watcher guides, provided by Wikispaces.
Consolidated Lunar Atlas – an online collection of Lunar resources maintained by The Lunar and Planetary Institute, a research institute that provides support services to NASA and the planetary science community.
For more information and resources about the Earth’s Moon, be sure to check out the websites of the various federal space agencies that helped contribute to our growing understanding of it. These include NASA’s Solar System Exploration, the European Space Agency’s The Moon – Our Neighbor and Destination: Moon, the Japan Aerospace Exploration Agency’s (JAXA) Lunar Exploration Program.
Welcome back to Constellation Friday! Today, in honor of the late and great Tammy Plotner, we will be dealing with “Berenice’s Hair” – the Coma Berenices constellation!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.
One of these is the constellation Coma Berenices, an ancient constellation located in the norther skies. In the Almagest, Ptolemy considered the asterism to be part of the constellation Leo. Today, it is one of the 88 constellations recognized by the International Astronomical Union, and is bordered by the constellations of Canes Venatici, Ursa Major, Leo, Virgo and Boötes.
Name and Meaning:
In mythology, it is easy to see why this dim collection of stars was once associated with Leo and considered to be the tuft of hair at the end of the Lion’s tail. However, as the years passed, a charming legend grew around this sparkling group of stars. Since the time of Ptolemy, this grouping of stars was recognized and although he didn’t list it as one of his 88 constellations, he did refer to is as “Berenice’s Hair”.
Coma Berenices as seen by the naked eye. Credit: Till Credner/ AlltheSky.com
As legend would have it, the good Queen Berenice II of Egypt offered to sacrifice her beautiful long hair to Aphrodite for the safe return of her husband from battle. When she cut off her locks and placed it on the altar and returned the next day, her sacrifice was gone. To save his life, the court astronomer proclaimed Aphrodite had immortalized Berenice’s gift in the stars… and thus the Lion lost his tail and the astronomer saved his hide!
History of Observation:
Like many of the 48 constellations recognized by Ptolemy, Coma Berenices traces it routes back to ancient Mesopotamia. To Babylonian astronomers, it was known as Hegala, which translated to “which is before it”. However, the first recorded mention comes from Conon of Samos, the 3rd century BCE court astronomer to Ptolemy III Euergetes – the Greek-Egyptian king. It was named in honor of his consort, Berenice II, who is said to have cut off her long hair as a sacrifice to ensure the safety of the king.
The constellation was named “bostrukhon Berenikes” in Greek, which translates in Latin to “Coma Berenices” (or “Berenice’s hair”). Though it was previously designated as its own constellation, Ptolemy considered it part of Leo in his 2nd century CE tract the Almagest, where he called it “Plokamos” (Greek for “braid”). The constellation was also recognized by many non-western cultures.
In Chinese astronomy, the stars making up Coma Berenices belonged to two different areas – the Supreme Palace Enclosure and the Azure Dragon of the East. Eighteen of the constellation’s stars were in an area known as Lang wei (“seat of the general”). To Arabic astronomers, Coma Berenices was known as Al-Du’aba, Al Dafira and Al-Hulba, forming the tuft of the constellation Leo (consistent with Ptolemy’s designation).
Fragment of Mercator’s 1551 celestial globe, showing Coma Berenices. Credit: Harvard Map Collection
By the 16th century, the constellation began to be featured on globes and maps produced by famed cartographers and astronomers. In 1602, Tycho Brahe recognized it as its own constellation and included it in his star catalogue. In the following year, it was included in Johann Bayer’s famed celestial map, Uranometria. In 1920, it was included by the IAU in the list of the 88 modern constellations.
Notable Objects:
Despite being rather dim, Coma Berenices is significant because it contains the location of the North Galactic Pole. It is comprised of only 3 main stars, but contains 44 Bayer/Flamsteed designated members. Of its main stars, Alpha Comae Berenices (aka. Diadem) is the second-brightest in the constellation.
The name is derived from the Greek word diádema, which means “band” or “fillet”, and represents the gem in Queen Berenice’s crown. It is sometimes known by its other traditional name, Al-Zafirah, which is Arabic for “the braid”. It is a binary star composed of two main sequence F5V stars that are at a distance of 63 light years from Earth.
The Black Eye Galaxy (Messier 64). Credit: NASA/The Hubble Heritage Team (AURA, STScI)
It’s brightest star, Beta Comae Berenices, is located 29.78 light years from Earth and is a main sequence dwarf that is similar to our Sun (though larger and brighter). It’s third major star, Gamma Comae Berenices, is a giant star belonging to the spectral class K1II and located about 170 light years from Earth.
Coma Berenices is also home to several Deep Sky Objects, which include spiral galaxy Messier 64. Also known as the Black Eye Galaxy (Sleeping Beauty Galaxy and Evil Eye Galaxy), this galaxy is located approximately 24 million light years from Earth. This galaxy has a bright nucleus and a dark band of dust in front of it, hence the nicknames.
Then there is the Needle Galaxy, which lies directly above the North Galactic Pole and was discovered by Sir William Herschel in 1785. It is one of the most famous galaxies in the sky that can be viewed edge-on. It lies at a distance of about 42.7 million light years from Earth and is believed to be a barred spiral galaxy from its appearance.
Coma Berenices is also home to two prominent galaxy clusters. These includes the Coma Cluster, which is made up of about 1000 large galaxies and 30,000 smaller ones that are located between 230 and 300 million light years from Earth. South of the Coma Cluster is the northern part of the Virgo Cluster, which is located roughly 60 million light years from Earth.
The globular cluster Messier 53 (NGC 5024), located in the Coma Berenices constellation. Credit: NASA (Wikisky)
Other Messier Objects include M53, a globular cluster located approximately 58,000 light years away; Messier 100, a grand design spiral galaxy that is one of the brightest members of the Virgo cluster (located 55 million light years away); and Messier 88 and 99 – a spiral galaxy and unbarred spiral galaxy that are 47 million and 50.2 million light years distant, respectively.
Finding Coma Berenices:
Coma Berenices is best visible at latitudes between +90° and -70° during culmination in the month of May. There is one meteor shower associated with the constellation of Coma Berenices – the Coma Berenicid Meteor shower which peaks on or near January 18 of each year. Its fall rate is very slow – only one or two per hour on average, but these are among the fastest meteors known with speeds of up to 65 kilometers per second!
For both binoculars and telescopes, Coma Berenices is a wonderland of objects to be enjoyed. Turn your attention first to the brightest of all its stars – Beta Coma Berenices. Positioned about 30 light years from Earth and very similar to our own Sun, Beta is one of the few stars for which we have a measured solar activity period – 16.6 years – and may have a secondary activity cycle of 9.6 years.
Now look at slightly dimmer Alpha. Its name is Diadem – the Crown. Here we have a binary star of equal magnitudes located about 65 light years from our solar system, but it’s seen nearly “edge-on” from the Earth. This means the two stars appear to move back-and-forth in a straight line with a maximum separation of only 0.7 arcsec and will require a large aperture telescope with good resolving power to pull them apart. If you do manage, you’re separating two components that are about the distance of Saturn from the Sun!
The location of the northern constellation Coma Berenices. Credit: IAU/Sky&Telescope magazine
Another interesting aspect about singular stars in Coma Berenices is that there are over 200 variable stars in the constellation. While most of them are very obscure and don’t go through radical changes, there is one called FK Comae Berenices which is a prototype of its class. It is believed that the variability of FK Com stars is caused by large, cool spots on the rotating surfaces of the stars – mega sunspots! If you’d like to keep track of a variable star that has notable changes, try FS Comae Berenices (RA 13 3 56 Dec +22 53 2). It is a semi-regular variable that varies between 5.3m and 6.1 magnitude over a period of 58 days.
For your eyes, binoculars or a rich field telescope, be sure to take in the massive open cluster Melotte 111. This spangly cloud of stars is usually the asterism we refer to as the “Queen’s Hair” and the area is fascinating in binoculars. Covering almost 5 full degrees of sky, it’s larger than most binocular fields, but wasn’t recognized as a true physical stellar association until studied by R.J. Trumpler in 1938.
Located about 288 light years from our Earth, Melotte 111 is neither approaching nor receding… unusual – but true. At around 400 million years old, you won’t find any stars dimmer than 10.5 magnitude here. Why? Chances are the cluster’s low mass couldn’t prevent them from escaping long ago…
Now turn your attention towards rich globular cluster, Messier 53. Achievable in both binoculars and small telescopes, M53 is easily found about a degree northwest Alpha Comae. At 60,000 light years away from the galactic center, it’s one of the furthest globular clusters away from where it should be. It was first discovered by Johann Bode in 1755, and once you glimpse its compact core you’ll be anxious to try to resolve it.
The Needle Galaxy (NGC 4565). Credit: ESO
With a large telescope, you’ll notice about a degree further to the east another globular cluster – NGC 5053 – which is also about the same physical distance away. If you study this pair, you’ll notice a distinct difference in concentrations. The two are very much physically related to one another, yet the densities are radically different!
Staying with binoculars and small telescopes, try your hand at Messier 64 – the “Blackeye Galaxy”. You’ll find it located about one degree east/northeast of 35 Comae. While it will be nothing more than a hazy patch in binoculars, smaller telescopes will easily reveal the signature dustlane that makes M64 resemble its nickname. It is one of the brightest spiral galaxies visible from the Milky Way and the dark dust lane was first described by Sir William Herschel who compared it to a “Black Eye.”
Now put your telescope on Messier 100 – a beautiful example of a grand-design spiral galaxy, and one of the brightest galaxies in the Virgo Cluster. This one is very much like our own Milky Way galaxy and tilted face-on, so we may examine the spiral galaxy structure. Look for two well resolved spiral arms where young, hot and massive stars formed recently from density perturbations caused by interactions with neighboring galaxies. Under good observing conditions, inner spiral structure can even be seen!
Try lenticular galaxy Messier 85. In larger telescopes you will also see it accompanied by small barred spiral NGC 4394 as well. Both galaxies are receding at about 700 km/sec, and they may form a physical galaxy pair. How about Messier 88? It’s also one of the brighter spiral galaxies in the Virgo galaxy cluster and in a larger telescope it looks very similar to the Andromeda galaxy – only smaller.
How about barred spiral galaxy M91? It’s one of the faintest of the Messier Catalog Objects. Although it is difficult in a smaller telescope, its central bar is very strong in larger aperture. Care to try Messier 98? It is a grand edge-on galaxy and may or may not be a true member of the Virgo group. Perhaps spiral galaxy Messier 99 is more to your liking… It’s also another beautiful face-on presentation with grand spiral arms and a sweeping design that will keep you at the eyepiece all night!
There are other myriad open clusters and just as many galaxies waiting to be explored in Coma Berenices! It’s a fine region. Grab a good star chart and put a pot of coffee on to brew. Comb the Queen’s Hair for every last star. She’s worth it.
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Moonrise is the first appearance of the Moon over the Earth’s horizon.
Unlike the Sun, the rising of the Moon changes from day to day and location to location because the Moon is orbiting the Earth. The Moon takes just over 27 days to complete an orbit around the Earth, so you can actually trace its movement in the sky from hour to hour. This is why a lunar eclipse only lasts a few hours. That’s how long it takes for the Moon to pass through the Earth’s shadow.
The movement of the Moon comes from both the rotation of the Earth – which makes the Sun and the stars move through the sky, as well as the orbital speed of the Moon.
Where and when the Moon rise depends on your location on Earth. So you can’t just see a generic table of moon rise times.
Fortunately, the Internet comes to the rescue. Here are some links to some calculators that will help you find out what time the Moon will rise in your specific location.
Moonrise and Moonset at Specified Location (NASA) – This calculator lets you punch in your specific latitude and longitude, year and month and then see a table of times that the Moon will rise and set for your location.
Farmer’s Almanac – The Farmer’s Almanac website has a tool that lets you put in your ZIP or Postal Code and date and then see a list of moonrise and sunrise times. You can also browse by city. This is better if you don’t know your latitude and longitude.
US Naval Observatory – This website lets you retrieve moonrise/sunrise time table for an entire year.
We have written many articles about the Moon on Universe Today. Here’s a story about building a moon base.
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We’re back to a themeless questions show. We’re right across the Universe this time. Why are the planets lined up in a nice flat plane? Why are there no greenstars? And is the Oort Cloud contaminating our understanding of the cosmic microwave background radiation? If you’ve got a question for the Astronomy Cast team, please email it in to [email protected] and we’ll try to tackle it for a future show. Please include your location and a way to pronounce your name.
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What lurks in the eerie fractures of Enceladus that slash across the moon’s south polar region? The Cassini spacecraft will make a Halloween flyby of Enceladus and focus its cameras and other optical remote sensing instruments on the mysterious tiger-stripe-like features seen on this strange moon of Saturn. This flyby comes just over three weeks after a previous flyby of the same moon, and then just a few days later, on November 3, Cassini will make a flyby of Titan, on the inbound leg of its orbit around the ringed world. What tricks do the Cassini scientists have up their sleeves for this flyby? Will we be treated to some spectacular images? And what about those spooky sounds from Saturn?
For the Oct. 31 flby, the spacecraft will zoom by the Enceladus at 17.7 km/sec (39,600 mph, cruising just 197 km (122 miles) from the moon’s surface. Cassini will approach the moon on a fast, inclined trajectory over the northern hemisphere and will depart over the southern hemisphere. The closest approach occurs on October 31st at 17:14:51 UT over latitude 28° S and longitude 97° W. The Optical Remote Sensing (ORS) instruments are at the focus of the science operations during this fly-by. The Imaging Science Subsystem camera will execute a sophisticated series of images starting just 2 minutes after closest-approach, obtaining images of the south polar “tiger stripes” at resolutions as high as 8.4 m/pixel. Enceladus will be in eclipse (in Saturn’s shadow) for about 2.5 hours, starting about 50 minutes after closest-approach.
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Want to know when the next full moon is going to happen? Here’s a list of all the full moons, from 2008 to 2012. This full moon schedule also includes the blue moons that will happen. Please keep in mind that all the full moon dates for set for universal time (the same as Greenwich Time), so you’ll need to convert the time to your local time zone. The full moon is the worst time to do astronomy because the light of the Moon washes out the light from dim objects.
Pluto and Charon. Credit: Antonello Medugno and Daniele Gasparri
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This past summer, a group of seven amateur astronomers from Italy worked on an observation campaign of Pluto, with hopes of capturing an image of its moon, Charon. “Imaging Charon is very difficult and nobody has spotted it with amateur equipment, so far,” said Daniele Gasparri, one of the members of the group. The team made several attempts, and finally, one member of the group, Antonello Medugno, took this interesting image. “After many calculations,” said Gasparri, “we are sure that this image shows clearly Pluto and Charon, for the first time with amateur equipment.” Comparing the image to the graphic which shows the position of Pluto and Charon on the same date, it’s obvious, they nailed it! This is quite a feat considering their equipment was an “amateur” 14-inch telescope! Also, as The Bad Astronomers points out, Charon wasn’t discovered until 1978, and then a 61-inch telescope was used!
Compare their image to one taken by Hubble:
Hubble image of Pluto and Charon. Credit: NASA
Not bad!!
Gasparri is an astronomy student, and a contributor to the Italian astronomy magazine Coelum. With the support of the magazine, he coordinated the effort to image Charon. Medugno used an 14″ Schmidt-Cassegrain telescope, a Starlight Xpress SXV-H9 CCD camera and a R-IR passband filter.
The image was processed using the Lucy-Richardson Algorithm of the RAW image, composed of 21 frames of 6 seconds of exposure each, with a focal of 8900mm. “All data confirm the image: the magnitude, separation, and position angle,” said Gasparri. Nice work! Check out Gasparri’s website of more astronomical images he has taken.
