Posted on by Fraser Cain

The Strange Nebula Around Eta Carinae

One of the five PHOENIX spectrograph of Eta Carinae. Image credit: Gemini Observatory/AURA. Click to enlarge
Eta Carinae is an unusual variable star just 8,000 light years away from Earth. It’s about 100 times more massive than our Sun – one of the most massive known – and it shines about 5 million times brighter than the Sun. It’s surrounded by an unusual cloud of material known as the Homunculus Nebula, which astronomers believe was created by successive explosions on the star’s surface. The Gemini Observatory has revealed a shockwave of expanding material moving through space at 500 km/second (310 miles/s).

Although the Homunculus Nebula around the massive star Eta Carinae has been the subject of intense study for many years, it has always been reluctant to divulge its innermost secrets. However, an important chapter in the recent evolution of this unique star was revealed when Nathan Smith (University of Colorado) used the high-resolution infrared spectrograph PHOENIX on the Gemini South telescope to observe the bipolar nebula surrounding Eta Carinae.

Multi-slit spectroscopy allowed Smith to reconstruct both the geometry and the velocity structure of the expanding gas in the nebula based on the behavior of the molecular line of hydrogen H2 at 2.1218 microns and the atomic line of ionized iron [Fe II] at 1.6435 microns.

Analysis of the PHOENIX spectrum shows a very well-defined shell structure expanding ballistically at about 500 kilometers per second. A “thick,” warm inner dust shell traced by [Fe II] emission is surrounded by a cooler and denser outer shell that is traced by strong H2 emission. Even though the outer H2 skin is remarkably thin and uniform it contains about 11 solar masses of gas and dust ejected over a period of less than five years. The Gemini spectra show that the density in the outer shell may reach 107 particles per cm3.

The spatio-kinematic structure of H2 emission at the pinched waist of the nebula helps explain the unusual and complex structures seen in other high-resolution images. The current shape of the Homunculus nebula is of two well-defined polar lobes outlined by an outer massive shell of gas and dust. Smith states that these Gemini/PHOENIX data indicate that most of the mass lost during the Great Eruption of the mid-nineteenth century was limited to the high latitudes of the star, with almost all of the mechanical energy escaping between 45 degrees and the pole.

“The mass distribution in the nebula indicates that its shape is a direct result of an aspherical explosion from the star itself, instead of being pinched at the waist by the surrounding circumstellar material,” said Smith.

For more details read “The Structure of the Homunculus: I. Shape and Latitutude Dependence from H2 and [Fe II] velocity Maps of Eta Carinae,” by Nathan Smith, The Astrophysical Journal, in press or at astro-ph/0602464.

Original Source: Gemini Observatory

Posted on by Fraser Cain

Mars Rovers Head for New Sites After Studying Layers

Coarse-grained layers inside Mars’ Gusev Crater. Image credit: NASA/JPL/Cornell. Click to enlarge
NASA engineers have moved the Spirit Mars rover to a safe North-facing slope to ride out the Martian winter. Since the rover is in the Southern hemisphere, it gets much less sunlight during the Winter. This maneuver was made more difficult because its right-front wheel has stopped working – the robot is dragging it along like an anchor. Spirit requires a good angle towards the sun to catch energy from the Sun onto its solar panels. It needs to store enough electricity to run the overnight heaters that protect its electronics.

NASA’s Mars rover Spirit has reached a safe site for the Martian winter, while its twin, Opportunity, is making fast progress toward a destination of its own.

The two rovers recently set out on important — but very different — drives after earlier weeks inspecting sites with layers of Mars history. Opportunity finished examining sedimentary evidence of ancient water at a crater called “Erebus,” and is now rapidly crossing flat ground toward the scientific lure of a much larger crater, “Victoria.”

Spirit studied signs of a long-ago explosion at a bright, low plateau called “Home Plate” during February and March. Then one of its six wheels quit working, and Spirit struggled to complete a short advance to a north-facing slope for the winter. “For Spirit, the priority has been to reach a safe winter haven,” said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the Mars Exploration Rover project.

The rovers have operated more than eight times as long as their originally planned three-month explorations on Mars. Each has driven more than 6.8 kilometers (4.2 miles) about 11 times as far as planned. Combined, they have returned more than 150,000 images. Two years ago, the project had already confirmed that at least one place on Mars had a wet and possibly habitable environment long ago. The scientific findings continue.

Opportunity spent most of the past four months at Erebus, a highly eroded impact crater about 300 meters (1,000 feet) in diameter, where the rover found extensive exposures of thin, rippled layering interpreted as a fingerprint of flowing water. “What we see at Erebus is a thicker interval of wetted sediment than we’ve seen anywhere else,” said Dr. John Grotzinger of the California Institute of Technology, “The same outcrops also have cracks that may have formed from wetting and drying.”

In mid-March, Opportunity began a 2-kilometer (1.6-mile) trek from Erebus to Victoria, a crater about 800 meters (half a mile) across, where a thick sequence of sedimentary rocks is exposed. In the past three weeks, Opportunity has already driven more than a fourth of that distance.

At Home Plate, Spirit found coarse layering overlain by finer layering in a pattern that fits accumulation of material falling to the ground after a volcanic or impact explosion. In one place, the layers are deformed where a golfball-size rock appears to have fallen on them while they were soft. “Geologists call that a ‘bomb sag,’ and it is strong evidence for some kind of explosive origin,” Squyres said. “We would like to have had time to study Home Plate longer, but we needed to head for a north-facing slope before winter got too bad.”

Spirit is in Mars’ southern hemisphere, where the sun is crossing lower in the northern sky each day. The rovers rely on solar power. The amount available will keep dropping until the shortest days of the Mars winter, four months from now. To keep producing enough electricity to run overnight heaters that protect vital electronics, Spirit’s solar panels must be tilted toward the winter sun by driving the rover onto north-facing slopes. However, on March 13 the right-front wheel’s drive motor gave out. Spirit has subsequently driven about 80 meters (262 feet) using five wheels and dragging the sixth, but an initial route toward a large hill proved impassable due to soft ground. Last week, the team chose a smaller nearby ridge, dubbed “Low Ridge Haven,” as the winter destination. Spirit reached the ridge Sunday and has a favorable 11-degree tilt toward the north.

“We have to use care choosing the type of terrain we drive over,” Dr. Ashitey Trebi-Ollennu, a rover planner at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., said about the challenge of five-wheel driving. In tests at JPL, the team has been practicing a maneuver to gain additional tilt by perching the left-front wheel on a basketball-size rock.

Spending eight months or so at Low Ridge Haven will offer time for many long-duration studies that members of the science team have been considering since early in the mission, said Dr. Ray Arvidson of Washington University in St. Louis, deputy principal investigator. These include detailed mapping of rocks and soils; in-depth determination of rock and soil composition; monitoring of clouds and other atmospheric changes; watching for subtle surface changes due to winds; and learning properties of the shallow subsurface by tracking surface-temperature changes over a span of months.

JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Exploration Rover Project for the NASA Science Mission Directorate.

For images and information about the rovers, see http://www.nasa.gov/rovers or http://marsrovers.jpl.nasa.gov .

For information about NASA and agency programs on the Web, visit http://www.nasa.gov .

Original Source: NASA News Release

Posted on by Mark Mortimer

Book Review: Destination Moon


Perhaps Krafft Ehricke put it best when he said if God wanted us to be a spacefaring race, He would have given us a Moon. The Apollo Space Program validated this statement by placing astronauts on the lunar surface. Rod Pyle in his book entitled Destination Moon � The Apollo Missions in the Astronauts’ Own Words brings back those heady days when anything seemed possible, if only we had the will.

Today, with NASA’s sights reset upon our Moon, there are many people with the desire to revisit their earlier sojourns to the same locale. A generation has matured without experiencing the euphoria of proving that the Earth is round, that it orbits the Sun and that people can walk on land other than of Earth. The Apollo Space Program showed that the universe is indeed a big place and that people aren’t inherently constrained to one little planet. Using technology of the day, stronauts rocketed up to the Moon, studied the geology and drove vehicles about the surface. Twelve people stood on the surface, surveyed the landscape, poked and prodded the rocks and left foot prints. Hundreds of thousands of others helped put them there. Those times were indeed heady for humankind.

Pyle’s objective with his book is to transport the reader back to that time of breathless wonder, to enjoy and (re) experience the Apollo program as those who did firsthand. To achieve this, he uses a picture book format with a superb collection of photographs culled from thousands of original negatives. Vibrant, evocative photographs fill the pages. Square images take up the whole page, while rectangular images expand across two. Most are in colour, though many of the views of the lunar surface look black and white for obvious reasons. The clarity of each is sharp, well depicting the memorable moment, and strongly evocative of the times. With the emotion transfixed on the many displayed faces, it is very easy to return to the times of Apollo.

The book’s title is also accurate when it states that the missions are discussed in the astronauts’ own words. This is because Pyle uses the astronauts’ mission dialogue and interviews straight from NASA. These are the astronauts own words but they contain nothing original. However, the translation’s of Pete Conrad singing are particularly humorous and the chosen passages highlight the flavour of the particular mission. Throughout these dialogues, brief explanatory notes orient the reader and put the dialogue in context. In all, these provide a valuable reference when viewing the photographs.

Pyle uses a chronological format through the book. He begins with outlines of Apollo 1, 7 and 8, the preparations for flight, the testing and the experience of failure. Next he combines Apollo 9 and 10 and the success of all up testing. Then he dedicates a chapter for each of the following 7 missions. With the description of each mission, he includes the official crew pictures to remind the reader of the human element. He closes with a chapter describing Al Bean’s artwork and thoughts on spaceflight and the future. In addition to including the crew pictures for each mission, there are many spectacular photographs of the lunar surface. In the words of Buzz Aldrin, these really show the magnificent desolation of the topology. Photographs address many other times in the mission, such as pre-launch, the lunar module ascension to the command module, and, the return capsule hitting the water. With all these well chosen, striking pictures, this book makes a wonderful gift to someone who hasn’t partaken in the experience or anyone who wants to re-fresh the feelings of optimism from those days.

Walking on the Moon’s surface is possible, people have already done it! Rod Pyle in his book entitled Destination Moon � The Apollo Missions in the Astronauts’ Own Words provides dramatic evidence of this. He lets photographs do most of the talking as he returns the reader to the exciting days when people walked on the Moon. We may soon return.

Review by Mark Mortimer

Read more reviews online or purchase a copy from Amazon.com

Posted on by Fraser Cain

Swirly Stormy Saturn

Dynamic Saturn. Image credit: NASA/JPL/SSI. Click to enlarge
Saturn, up close and personal. In this Cassini image, you can see the subtle, swirling storms that roll across Saturn’s atmosphere. Unlike the Earth, Saturn is still a planet in formation; it’s continuing to slowly contract, which generates the massive amounts of heat that drive its dramatic weather systems. Cassini took this photograph on March 7, 2006 when it was 2.9 million kilometers (1.8 million miles) from Saturn.

Streamers, swirls and vortices roll across the dynamic face of Saturn.

Unlike Earth, where most of the weather is driven by the Sun, Saturn’s storms and circulation are driven in part by internal heating. Amazingly, the planet is still contracting (ever so slightly) from its formation, more than 4.5 billion years ago. This gravitational contraction liberates energy in the form of heat.

The image was taken in polarized infrared light with the Cassini spacecraft narrow-angle camera on March 7, 2006, at a distance of approximately 2.9 million kilometers (1.8 million miles) from Saturn. The image scale is 17 kilometers (10 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

Mars Wants You to Have a Nice Day

This is a photograph of the unusually happy Galle Crater on Mars. ESA’s Mars Express took a series of 5 images shaped like strips which were then assembled on computer to build up a single photograph. Galle Crater is 230 km (143 miles) across, and located on the eastern rim of the Argyre Planitia impact basin on Mars.

These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, show the Galle Crater, an impact crater located on the eastern rim of the Argyre Planitia impact basin on Mars.

The HRSC obtained these images during orbits 445, 2383, 2438, 2460 and 2493 with a ground resolution ranging between 10-20 metres per pixel, depending on location within the image strip.

The images show Crater Galle lying to the east of the Argyre Planitia impact basin and south west of the Wirtz and Helmholtz craters, at 51 degrees South and 329 degrees East.

The images of the 230 km diameter impact crater are mosaics created from five individual HRSC nadir and colour strips, each tens of kilometres wide.

A large stack of layered sediments forms an outcrop in the southern part of the crater. Several parallel gullies, possible evidence for liquid water on the Martian surface, originate at the inner crater walls of the southern rim.

Crater Galle, named after the German astronomer J.G. Galle (1812-1910), is informally known as the ‘happy face’ crater.

The ‘face’ was first pointed out in images taken during NASA’s Viking Orbiter 1 mission.

***image4:left***Its interior shows a surface which is shaped by ‘aeolian’ (wind-caused) activity as seen in numerous dunes and dark dust devil tracks which removed the bright dusty surface coating.

The colour scenes, false-colour and near true-colour, have been derived from three HRSC colour and nadir channels gathered during five overlapping orbits. The perspective views have been calculated from a mosaic of digital terrain models derived from the stereo channels.

The black-and-white high-resolution image mosaic was derived from the nadir channel which provides the highest detail of all channels. The resolution has been decreased for use on the Internet, to around 50 m per pixel.

Original Source: ESA Mars Express

Posted on by Fraser Cain

Hubble Finds Xena’s Only a Little Bigger Than Pluto

An artist’s illustration of Xena with its moon. Image credit: NASA Click to enlarge
The powerful Hubble Space Telescope has finally been brought to bear on the newly discovered 10th planet (aka Xena), to help answer the question: is it really bigger than Pluto? Hubble is the only instrument that can make an actual visible light observation of Xena’s diameter. Hubble found that Xena is is about 2400 km (1,490 miles) across, which makes it only 113 km (70 miles) larger than Pluto. This makes the 10th planet unusually bright, probably covered in brilliant white methane snow.

For the first time, NASA’s Hubble Space Telescope has seen distinctly the “tenth planet,” currently nicknamed “Xena,” and has found that it is only slightly larger than Pluto.

Though previous ground-based observations suggested that Xena’s diameter was about 30 percent greater than Pluto, Hubble observations taken Dec. 9 and 10, 2005, showed Xena’s diameter as 1,490 miles (with an uncertainty of 60 miles). Pluto’s diameter, as measured by Hubble, is 1,422 miles.

“Hubble is the only telescope capable of getting a clean visible-light measurement of the actual diameter of Xena,” said Mike Brown, planetary scientist at the California Institute of Technology in Pasadena, Calif. Brown’s research team discovered Xena, officially cataloged as 2003 UB313, and its results have been accepted for publication in the Astrophysical Journal.

Only a handful of images were required to determine Xena’s diameter. Located 10 billion miles from Earth with a diameter a little more than half the width of the United States, the object is 1.5 pixels across in Hubble’s view. That’s enough to make a precise size measurement.

Because Xena is smaller than previously thought, but comparatively bright, it must be one of the most reflective objects in the solar system. The only object more reflective is Enceladus, a geologically active moon of Saturn whose surface is continuously recoated with highly reflective ice by active geysers.

Xena’s bright reflectivity is possibly due to fresh methane frost on its surface. The object may have had an atmosphere when it was closer to the sun, but as it moved to its current location farther away this atmosphere would have “frozen out,” settling on the surface as frost.

Another possibility is that Xena leaks methane gas continuously from its warmer interior. When this methane reaches the cold surface, it immediately freezes solid, covering craters and other features to make it uniformly bright to Hubble’s telescopic eye.

Xena’s takes about 560 years to orbit the sun, and it is now very close to aphelion (the point on its orbit that is farthest from the sun).Brown next plans to use Hubble and other telescopes to study other recently discovered Kuiper Belt objects that are almost as large as Pluto and Xena. The Kuiper Belt is a vast ring of primordial icy comets and larger bodies encircling Neptune’s orbit.

Finding that the largest known Kuiper Belt object is a virtual twin to Pluto may only further complicate the debate about whether to categorize the large icy worlds that populate the belt as planets. If Pluto were considered to be the minimum size for a planet, then Xena would fulfill this criterion, too. In time, the International Astronomical Union will designate the official name.

The Hubble Space Telescope is an international cooperative project between NASA and the European Space Agency. The Space Telescope Science Institute in Baltimore conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington

For electronic images and more Hubble news, visit: http://www.nasa.gov/hubble

Original Source: NASA News Release

Update, Pluto is no longer a planet. Why is Pluto not a planet?

Posted on by Fraser Cain

Podcast: Dark Energy Stars

Black holes… you know. Cosmic singularities that can contain the mass of billions of stars like our Sun. Where the pull of gravity is so strong, nothing, not even light can escape their fearsome grasp. They’re the source of much discussion, indirect observation and science fiction speculation. But according to George Chapline from Lawrence Livermore National Laboratory in California, they don’t exist. Instead we have dark energy stars, which are connected to that mysterious force accelerating the expansion of the Universe.
Continue reading “Podcast: Dark Energy Stars”

Posted on by Fraser Cain

What’s Up This Week – April 10 – April 17, 2006

Class I Flamsteed. Image credit: Ricardo Borba. Click to enlarge.
Greetings, fellow SkyWatchers! This week will be filled with meteor showers and moon shine – bright nebula and galaxies. The “Ring King” Saturn is now at its best, so get out under the stars, because…

Here’s what’s up!

Monday, April 10 – Be sure to get up before dawn to enjoy the Virginid meteor shower. The radiant point will be near Gamma in the bowl of Virgo. The fall rate of 20 per hour is above average for meteor showers, and with the Moon out of the equation this morning, you’re in for a treat!

Tonight we’ll start by identifying the large mare just south of central on the lunar disc called Oceanus Procellarum. Look almost centrally within its grey expanse for a large crater which has mostly melted down. This “ghost crater” has no name, but look along its edge for Class I Flamsteed. It is very near here that Surveyor 1 still stands. It made its landing on June 2, 1966 and sent back more than 11,000 pictures of the rock strewn, desert-like floor. This area was one of the first chosen for an Apollo mission landing, but was later scratched for a more central location.

Now let’s move on to 3.2 magnitude Mebsuta – Epsilon Geminorum. Mebsuta is the brightest star (other than Castor) in northwestern Gemini. It has a very distant 9th magnitude companion. As you observe Epsilon, keep in mind its spectral class (G8) is very similar to our Sun. Despite this, Mebsuta glows with an intensity of light 7600 times brighter. It’s one of a rare class of stars called “yellow supergiants” – stars whose nuclear cores are vastly swollen due to advanced age and which have taken on “planetary” proportions. Why planetary? Because the planet Venus would find itself orbiting inside Mebsuta’s 4600 degree C temperature photosphere!

Tuesday, April 11 – Today is the birthday of William Wallace Campbell. Born in 1862, Campbell went on to become the leader of stellar motion and radial velocity studies. He was the director of Lick Observatory from 1901 to 1930, and also served as president of the University of California and the National Academy of Sciences. Also born on this day – but in 1901 – was Donald H. Menzel – assistant astronomer at Lick Observatory. Menzel became Director of Harvard Observatory, an expert on the Sun’s coronosphere and held a genuine belief in the extraterrestrial nature of UFOs. Today in 1960, the first radio search for extraterrestrial civilizations was started by Frank Drake (Project Ozma). In 1986, Halley’s Comet closed within 65 million kilometers of the Earth ? as close as it would get.

If you would like to try out a pair of less obvious lunar features, start out again tonight at Oceanus Procellarum – a vast, grey “sea” encompassing most of the northwestern portion of the Moon. On the terminator to its southwest (and almost due west geographically), you will see two craters nearly identical in size and depth. The southern crater is Billy – one of the darkest floored areas on the Moon. Inside Billy’s bright rim, you will notice an interior as featureless as a mare. North of Billy is Hansteen, whose interior is much brighter and shows complex details. Comparing the two will show Billy was once filled with smooth lava, while Hansteen avoided that fate and shows its native scarred interior.

Although skies will be bright this evening, we can still have a look at brilliant Arcturus – a star whose distance from the Earth (10 parsecs) and radial velocity (less than 200 meters per second) can almost be considered a benchmark. By skydark you will see 0.2 magnitude Arcturus – the brightest star in Bootes and 4th brightest star in the night sky – some 30 degrees above the eastern horizon. Apparent to the eye is Arcturus’ orange color. Because a star’s intrinsic luminosity relates to its apparent brightness and distance, Arcturus’ absolute magnitude is almost precisely the same as its apparent magnitude. Just because Arcturus’ radial velocity is nearly zero doesn’t mean it isn’t on the move relative to our Sun. Arcturus star is now almost as close as it will ever get and its large proper motion – perpendicular to our line of sight – exceeds 125 kilometers per second. Every 100 years Arcturus moves almost 1 degree across the sky!

Wednesday, April 12 – Today in 1961, Yuri Gagarin made one full orbit of the Earth aboard Vostok 1, while also becoming the first human in space. Also today (in 1981) Columbia became the first Space Shuttle to launch.

Tonight let’s launch our lunar explorations as we head for the far north for an “on the edge” feature – Pythagoras. Named for the Greek philosopher and mathematician, you will see this smooth, walled plain as a thin, bright ellipse standing out well against the background of northern Sinus Iridum. Pythagoras is one of the deepest craters in the northern quadrant and would be even more spectacular if visible from overhead – rather than at an angle. Look for its tall and prominent central peak.

Although the Moon will interfere with most studies, we can still check out Iota Cancri – a fine wide disparate double of magnitudes 4.0 and 6.6 separated by some 30 arc seconds. This true binary is so distant from one another that they take over 60,000 years to complete a single orbit around their common center of gravity! Located slightly less than a fist’s width due north of M44, this pair is about 300 light years distant. Both stars shine with a light considerably brighter than our Sun and observers may note a subtle gold and pale blue color contrast between them.

Thursday, April 13 – Tonight’s Full Moon is often referred to as the “Pink Moon” of April. As strange as the name may sound, it actually comes from the herb moss pink- or wild ground phlox. April is the time of blossoming and the “pink” is one of the earliest widespread flowers of the spring season. As you might expect, this Full Moon is also known by other names as well. How about the “Full Sprouting Grass Moon,” the “Egg Moon,” or the coastal tribe based “Full Fish Moon” as we’ve entered the season when fish swim upstream to spawn.

Tonight let’s take a journey towards the 25th brightest star in the night sky – 1.3 magnitude Regulus. Regulus, known as “The Little King,” is the brightest star in Leo. At 77 light-years away, this star is considered a “dwarf” despite shining with a visible light almost 150 times that of Sol. The orange-red giant Arcturus and the blue white “dwarf” Regulus both share a common absolute magnitude very close to 0. The reason the two stars shine with a similar intrinsic brightness – despite widely different physical sizes – is Regulus’ photosphere is more than twice as hot (12,000 C) as Arcturus. While observing Regulus, look for a distant companion of magnitude 8.5. Normally low powers would best concentrate the companion’s light, but try a variety of magnifications to help improve contrast. For those with large aperture scopes, look for a 13.1 magnitude “companion’s companion” a little more than 2 arc seconds away!

Friday, April 14 – Today is the birthday of Christian Huygens. Born in 1629, the Dutch scientist went on to become one of the leaders in his field during the 17th century. Among his achievements were promoting the wave theory of light, patenting the pendulum clock, and improving the optics of telescopes by inventing a new type eyepiece and reducing false color through increasing the focal length of refractor telescopes. Huygens was the first to discover Saturn’s rings and largest satellite – Titan. Of the rings, Huygens said, “Saturn: encircled by a ring, thin and flat, nowhere touching, and inclined to the ecliptic.”

To honor Huygen’s achievements and get a sense just how “on the edge” his observations were at the time, consider the fact Huygens used a home built instrument of 12 foot (336.7) focal length and little more than 2 inches in aperture (57mm). Tonight, why not have a low power look at Saturn using your smallest scope. At what magnification does it become clear to you that the planet has “lost its ears” and gained a ring?

Saturday, April 15 – Tonight keep a watch for the “April Fireballs.” This unusual name has been given to what may be a branch of the complex Virginid stream which began earlier in the week. The absolute radiant of the stream is unclear, but most of its long tails will point back toward southeastern skies. These bright bolides can possibly arrive in a flurry – depending on how much Jupiter’s gravity has perturbed the meteoroid stream. Even if you only see one tonight, keep a watch in the days ahead. The time for “April Fireballs” lasts for two weeks. Just seeing one of these brilliant streaks will put a smile on your face!

While thinking of Jupiter, why not search for the planet’s ghost? The “Ghost of Jupiter” sits after skydark in the constellation Hydra. Start at Alpha Hydrae and head east about a fist’s width to find Lambda within a field of nearby fainter stars. Continue less than a fist southeast and locate Mu. You’ll find the “Ghost of Jupiter” (NGC 3242) lurking in the dark less than a finger-width due south. At magnitude 9, the NGC 3242 gives a strikingly blue-green appearance in even small scopes – despite being more than 1500 light years away.

Before we call it a night, let’s visit with Luna as we look along the southern shore of Mare Humorum and identify ancient crater Vitello. Notice how this delicate ring resembles earlier study Gassendi on the opposite shore.

Sunday, April 16 – With the later rise of the Moon, this is a fine opportunity to have a look at a group of galaxies between Leo’s paws. Start at Regulus and look due east toward Iota Leonis. Halfway between the two (less than a fist from Regulus) and two finger-widths northeast of Rho Leonis, you’ll encounter Messier Galaxies M95 and M96 – both within the same low power field of view. At magnitude 9.2, the brighter – and slightly rounder – M96 lies northeast of 9.7 magnitude M95. Pierre M?chain discovered both galaxies on March 20, 1781 and Messier added them to his catalog 4 days later. These two galaxies are two of the brightest members of the Leo I galaxy group located some 38 million light-years away.

To see another Messier member of the Leo I group, center on M96 and shift the galaxy south. From the north side of the low power field, the 9.3 magnitude galaxy M105, nearby 10th magnitude NGC 3384, and 12th magnitude NGC 3389 will come into view. M105 was discovered by M?chain on the night Messier catalogued M95 and 96 but was not formally added to Messier’s catalog. Based on M?chain’s observing notes, Helen Sawyer Hogg added it to Messier’s list in 1947 – along with galaxy M106 and globular cluster M107. M?chain failed to notice M105’s bright neighboring galaxy – NGC 3384. NGC 3384 is actually slightly brighter than the faintest Messier discovered – M91.

We’re not done yet! If you center on M105 and shift due north less than a degree and a half you will encounter 10th magnitude NGC 3377 – a small elongated galaxy with a stellar core. There are a dozen galaxies visible to moderate amateur instruments (through magnitude 12) in the Leo I region of the sky!

If you are out late enough to study the Moon, relocate previous study Petavius on the southern terminator. Just beyond its east wall, look for a bright ridge that extends from north to south separated by darkness from Petavius. This is Palitzsch, a very strange, gorge-like formation that looks as if it was caused by a meteor plowing through the Moon’s surface. Palitzsch’s true nature wasn’t known until 1954 when Patrick Moore resolved it as a “crater chain” using the 25″ Newall refractor at Cambridge University Observatory.

May all your journeys be at light speed… ~Tammy Plotner with Jeff Barbour.

Posted on by Fraser Cain

New Spacecraft Will Search for Lunar Ice

An artist’s conception of LRO on its way to the moon. Image credit: NASA Click to enlarge
NASA announced a new spacecraft today that will search for ice at the Moon’s southern pole: the Lunar CRater Observation and Sensing Satellite (LCROSS). The spacecraft will launch as a secondary payload with the Lunar Reconnaissance Orbiter in 2008. As it approaches the Moon, LCROSS will split into two spacecraft. The first will smash into the Moon’s south pole, and the second will fly through the resulting plume, analyzing it for traces of water. This mission will be developed on a shoestring; NASA has allocated a total of $80 million for its development.

NASA today announced that a small, ‘secondary payload’ spacecraft, to be developed by a team at NASA Ames Research Center, Moffett Field, Calif., has been selected to travel to the moon to look for precious water ice at the lunar south pole in October 2008.

The smaller secondary payload spacecraft will travel with the Lunar Reconnaissance Orbiter (LRO) satellite to the moon on the same rocket, the Evolved Expendable Launch Vehicle (EELV), to be launched from Kennedy Space Center, Florida. The NASA Ames team proposed the secondary payload mission, which will be carried out by the Lunar CRater Observation and Sensing Satellite (LCROSS).

“The LCROSS mission gives the agency an excellent opportunity to answer the question about water ice on the moon,” said Daniel Andrews of NASA Ames, whose team proposed the LCROSS mission. “We think we have assembled a very creative, highly innovative mission, turning the upper stage of the rocket that brought us to the moon into a substantial impactor on the moon.”

After launch, the secondary payload LCROSS spacecraft will arrive in the lunar vicinity independent of the LRO satellite. On the way to the moon, the LCROSS spacecraft’s two main parts, the Shepherding Spacecraft (S-S/C) and the Earth Departure Upper Stage (EDUS), will remain coupled.

As the spacecraft approaches the moon’s south pole, the upper stage will separate, and then will impact a crater in the south pole area. A plume from the upper stage crash will develop as the Shepherding Spacecraft heads in toward the moon. The Shepherding Spacecraft will fly through the plume, and instruments on the spacecraft will analyze the cloud to look for signs of water and other compounds. Additional space and Earth-based instruments also will study the 2.2-million-pound (1000-metric-ton) plume.

“The LCROSS mission will help us determine if there is water hidden in the permanently dark craters of the moon’s south pole,” said Marvin (Chris) Christensen, Robotic Lunar Exploration Program (RLEP) manager, and acting director of NASA Ames. “If we find substantial amounts of water ice there, it could be used by astronauts who later visit the moon to make rocket fuel,” Christensen added.

Earlier, NASA had requested proposals internally from its NASA field centers for existing or reasonably matured concepts for secondary payloads that would offer cost-effective contributions to RLEP.

To prepare for the return of astronauts to the moon, NASA will conduct various RLEP robotic missions from 2008 to potentially 2016 to study, to map and to learn about the lunar surface. These early missions will help determine lunar landing sites and whether resources, such as oxygen, hydrogen and metals, are available for use in NASA’s long-term lunar exploration objectives.

“Establishing research stations on the moon will give us the experience and capabilities to extend to Mars and beyond,” noted robotics deputy program manager Butler Hine of Ames.

“An exploration science program with a sustained human presence on the moon gives us the opportunity to conduct fundamental science in lunar geology, history of the solar system, physics and the biological response to partial (Earth) gravity,” said Christopher McKay, lunar exploration program scientist at Ames.

The space agency specified that the winning proposal must demonstrate an affordable concept beneficial to RLEP, according to the document that asked NASA centers to submit suggestions for the secondary payload. NASA noted that the secondary payload mission should cost no more than $80 million. NASA also required that the payload mass not exceed 2,205 pounds (1,000 kilograms).

NASA encouraged its field centers to team with industry to develop proposals. On Jan. 10, NASA issued a request for information to industry to allow businesses to provide secondary payload concepts to NASA. Each NASA center reviewed ideas from industry as well as secondary payload concepts developed internally.

NASA asked that the concepts advance the Vision for Space Exploration to include missions that evolve lunar science, characterize the lunar environment and support identification sites for future human missions as well as the utility of those sites.

The space agency said that it was looking for missions that demonstrate technology that could enhance future exploration, that show operational schemes to support exploration, that develop or emplace infrastructure in support of exploration, that advance commercial opportunities and those missions that would collect engineering data to support the Constellation program. That program is developing NASA’s new spaceship, the Crew Exploration Vehicle.

For images related to the LCROSS mission, please visit:
http://www.nasa.gov/centers/ames/multimedia/images/2006/lunarorbiter.html

For additional high-resolution images of the and historic information, please visit:
http://www.nasa.gov/centers/ames/news/releases/2004/moon/moon.html

http://lunar.arc.nasa.gov/

http://nssdc.gsfc.nasa.gov/planetary/lunarprosp.html

http://science.nasa.gov/newhome/headlines/ast31jul99_1.htm

Original Source: NASA News Release

Posted on by Fraser Cain

Astrophoto: Leo 1 by Bernhard Hubl

Leo 1 by Bernhard Hubl
Astronomers are beginning to see a pattern in what was previously viewed as the random distribution of galaxies tossed across the universe. Emerging is an understanding that the galaxies are distributed on the surface of huge bubbles whose interiors are void or contain material yet to be discovered. These bubbles are of various sizes but, in general, there are lots of them thus a helpful mental image of the universe’s organization may be something similar in appearance to soap suds. Where the edges of these bubbles meet, groups of galaxies tend to collect in bunches and this agrees with the observational evidence.

Our home Galaxy is called the Milky Way because the ancient Greeks rationalized its broad band of light arcing across the night sky was milk from the breast of the Queen of Gods, Hera. The Milky Way galaxy and thirty or more others which include M31, its two large satellites and M33 comprise what’s known as the Local Group. The Local Group of galaxies, in turn, interacts with four other nearby galaxy concentrations and it is thought that each of these clusters probably exchange members over some regular, but enormous, time scale.

Some of the members of the Local Group are actually satellites of our galaxy. Almost all of them are called dwarfs due to their small size and irregular shape. So far, twelve, maybe thirteen, have been identified, including the Large and Small Magellanic Clouds – more will likely be discovered. One of the most distant of these attendants, pictured here, is located about 900,000 light years from Earth and is called Leo 1.

Leo 1 was unknown until 1950 and was only visible through long exposure photographs until it was finally visually observed around 1990. The challenge with seeing or photgraphing this galaxy has less to do with its brightness than with the fact that it appears extremely close to the brightest star in the constellation Leo, which is called Regulus. Regulus is thousands of times more brilliant and the glare seen in optical instruments can wash out the presence of this small galaxy.

This remarkable photograph was produced by astronomer, Bernhard Hubl, at his imaging site in Schlierbach, Austria over a period of three nights during mid-March, 2006. This picture required over eight hours of exposure and was produced through a four inch aperture refractor with a 2 mega-pixel astronomical camera.

Do you have photos you’d like to share? Post them to the Universe Today astrophotography forum or email them, and we might feature one in Universe Today.

Written by R. Jay GaBany