Posted on by Fraser Cain

Gmail Invites

I made a mention in yesterday’s newsletter that I had a few Gmail invites left over. You know, this is Google’s competitor to Hotmail and Yahoo that gives you a free email address with one GB of space. It’s still in beta, but I’m really impressed with it so far. I made a small mention down at the bottom, but I was still deluged with email requests for a Gmail invite. I had posted 6 invites in the Universe Today forum, and they were snapped up in a few minutes.

Now, I know there are hundreds of you reading this newsletter with some Gmail invites to spare, so I was wondering if you could help out. Visit the forum, head down to the bottom and post any spare invite links that you have. I’ve posted instructions in the forum on how to do this. Do not email me directly asking for an invite.

Here’s a link to the thread in the forum where everyone is posting their invites. Please help out if you can.

Thanks!

Fraser Cain
Publisher
Universe Today

P.S. The Universe Today forum has nearly 3,000 members now from all around the world. Come, hang out, and chat with other space enthusiasts!

Posted on by Fraser Cain

Arizona Telescope Turned Into a Robot

Today, the world of astronomy meets the science fiction world of Isaac Asimov’s “I, Robot” with the commissioning of a new robotic telescope. While it lacks the humanoid qualities of the movie version, this robot will aid in humanity’s quest to understand the early universe by observing the most distant and powerful explosions known.

Located at the Fred L. Whipple Observatory on Mt. Hopkins, Arizona, the Peters Automated Infrared Imaging Telescope (PAIRITEL) is the first fully “robotic” infrared telescope in North America dedicated to observing transient astronomical events. The telescope, used for several years in a major all-sky survey (2MASS), has been refurbished to work autonomously. It will operate in tandem with NASA’s new gamma-ray burst satellite “Swift,” to be launched on November 8 from Kennedy Space Center.

With PAIRITEL, a team of astronomers led by Dr. Joshua Bloom of the Harvard Society of Fellows, Harvard-Smithsonian Center for Astrophysics (CfA) and UC Berkeley, hopes to pinpoint the gamma-ray burst explosions from the first and most distant stars in the universe. A gamma ray burst (GRB) is a quick flash of gamma-ray radiation lasting about a minute, accompanied by an afterglow emission of X-rays, visible, infrared, and radio light. The afterglow may be observable for days to weeks afterward. The majority of GRBs are believed to be due to massive stars that explode violently and release tremendous blasts of energy.

“Innovatively exploring the night sky in the time domain – seeing how things change from night to night, and even from minute to minute – is the next big frontier in astronomy,” said Bloom. “PAIRITEL was optimized to study cosmic events like GRBs that are here today and gone tomorrow.”

Peering back to a time when the universe was less than 1 billion years old is the holy grail of observational astronomy. So far, only energetic galaxy cores known as quasars have been used to probe the early universe. But gamma-ray burst afterglows, if astronomers are able to image them quickly, hold clear advantages over quasars. For up to one hour after the burst, afterglow brightnesses can reach up to 1000 times that of the brightest known quasar in the universe.

Also, explained Bloom, “The stars that create GRBs likely formed before the black holes that create quasars. So by looking for the youngest and most distant GRBs, we can study the earliest epochs of the universe.”

A key feature of PAIRITEL that will allow the location of distant GRBs is its rapid response time. PAIRITEL will receive signals from Swift and automatically move, in under 2 minutes, to the part of the sky where a GRB has appeared.

“My ultimate vision is to have astronomy robots talking to robots, deciding what to observe and how, with no human intervention,” said Bloom. “As it is, PAIRITEL only e-mails us when it’s found a particularly interesting source, or when something goes wrong and it needs help!”

Another key feature of PAIRITEL is its sensitivity at infrared wavelengths, setting this system apart from the bevy of visible-light robotic telescopes already in existence. Images taken with infrared filters (about twice the wavelength of visible light) are indispensable: visible light emitted from more than 12 billion light-years away is completely extinguished for observers on Earth. Bloom explained, “Forget about the dimming due to the extreme distances: the hydrogen gas between us and the explosions makes it like searching for a firefly behind a thick London fog. In the infrared we can peer through the shroud to the good stuff.” In addition, the unique camera on PAIRITEL takes pictures simultaneously at three different wavelengths of light, allowing for instantaneous full-color snapshots.

The Swift spacecraft will find GRBs at a rate 10 to 20 times higher than currently feasible, and should find more bursts in 6 months than all well-studied bursts to date. Bloom said he is most excited about using Swift and PAIRITEL “together to find the golden needle in the haystack – a high-redshift GRB that’s farther away than the most distant known galaxy or quasar.”

When PAIRITEL is not chasing down GRBs, it will be used to make precision measurements of supernovae to help determine the few fundamental parameters that dictate the expansion of the universe. Among other projects, Dr. Michael Pahre (CfA) will use PAIRITEL to study the near-infrared light of nearby galaxies to compare it with mid-infrared light in images obtained with NASA’s Spitzer Space Telescope. Harvard graduate student Cullen Blake, who has written software for the project, will also use PAIRITEL to try to find Earth-mass planets around brown dwarfs. Other PAIRITEL team members include: Prof. Mike Skrutskie (Univ. of Virginia), Dr. Andrew Szentgyorgyi (CfA), Prof. Robert Kirshner (Harvard University/CfA), Dr. Emilio Falco (CfA), Dr. Thomas Matheson (NOAO), and Dan Starr (Gemini Observatory, Hawaii). The staff of Mt. Hopkins-Wayne Peters, Bob Hutchins, and Ted Groner-worked on the automation of the telescope.

PAIRITEL, nearly 2 years after the inception of the project, is being dedicated today to the late Jim Peters, who worked for the Smithsonian Astrophysical Observatory, first on satellite tracking and then as a telescope operator on Mt. Hopkins for 25 years. His widow and son will be in attendance at the ceremony.

The project was funded by a grant from the Harvard Milton Fund. The telescope is owned by the Smithsonian Astrophysical Observatory and the infrared camera is on loan from the University of Virginia.

Additional information about Swift and PAIRITEL is available online at:

http://swift.gsfc.nasa.gov/docs/swift/swiftsc.html
http://pairitel.org/

Original Source: CfA News Release

Posted on by Fraser Cain

Mystery Object in the Milky Way’s Halo

Most of the stars in our Milky Way galaxy lie in a very flat, pinwheel-shaped disk. Although this disk is prominent in images of galaxies similar to the Milky Way, there is also a very diffuse spherical “halo” of stars surrounding and enclosing the disks of such galaxies.

Recent discoveries have shown that this outer halo of the Milky Way is probably composed of small companion galaxies ripped to shreds as they orbited the Milky Way.

A discovery announced today by the Sloan Digital Sky Survey (SDSS) reveals a clump of stars unlike any seen before. The findings may shed light on how the Milky Way’s stellar halo formed.

This clump of newly discovered stars, called SDSSJ1049+5103 or Willman 1, is so faint that it could only be found as a slight increase in the number of faint stars in a small region of the sky.

“We discovered this object in a search for extremely dim companion galaxies to the Milky Way,” explains Beth Willman of New York University’s Center for Cosmology and Particle Physics. “However, it is 200 times less luminous than any galaxy previously seen.”

Another possibility, adds Michael Blanton, an SDSS colleague of Willman’s at New York University, is that Willman 1 is an unusual type of globular cluster, a spherical agglomeration of thousands to millions of old stars.”

“Its properties are rather unusual for a globular cluster. It is dimmer than all but three known globular clusters. Moreover, these dim globular clusters are all much more compact than Willman 1”, explains Blanton. “If it’s a globular cluster, it is probably being torn to shreds by the gravitational tides of the Milky Way.”

The real distinction between the globular cluster and dwarf galaxy interpretations is that galaxies are usually accompanied by substantial quantities of dark matter, says Julianne Dalcanton, an SDSS researcher at the University of Washington. “Clearly the next step is to carry out additional measurements to determine whether there is any dark matter associated with Willman 1.”

SDSS consortium member Daniel Zucker of the Max Planck Institute for Astronomy in Heidelberg, Germany, says the Sloan Digital Sky Survey has proven to be “a veritable gold mine for studies of the outer parts of our galaxy and its neighbors, as shown by Dr. Willman’s discovery, and by our group’s earlier discovery of a giant stellar structure and a new satellite galaxy around the Andromeda Galaxy.”

If Willman 1 does turn out to be a dwarf galaxy, this discovery could shed light on a long-standing mystery.

The prevailing ‘Cold Dark Matter’ model predicts that our own Milky Way galaxy is surrounded by hundreds of dark matter clumps, each a few hundred light years in size and possibly populated by a dwarf galaxy.

However, only 11 dwarf galaxies have been discovered orbiting the Milky Way. Perhaps some of these clumps have very few embedded stars, making the galaxies particularly difficult to find.

“If this new object is in fact a dwarf galaxy, it may be the tip of the iceberg of a yet unseen population of ultra-faint dwarf galaxies,” suggests Willman.

The Milky Way has been an area of intense research by SDSS consortium members.

“The colors of the stars in Willman 1 are similar to those in the Sagittarius tidal stream, a former dwarf companion galaxy to the Milky Way now in the process of merging into the main body of our Galaxy,” explains Brian Yanny, an SDSS astrophysicist at The Department of Energy’s Fermi National Accelerator Laboratory, a leader in research on the Milky Way’s accretion of material.

Continues Yanny: “If Willman 1 is a globular cluster, then it may have piggybacked a ride into our Galaxy’s neighborhood on one of these dwarf companions, like a tiny mite riding in on a flea as it, in turn, latches onto a massive dog.”

“Whether it is a globular cluster or a dwarf galaxy, this very faint object appears to represent one of the building blocks of the Milky Way,” Willman said.

Original Source: SDSS News Release

Posted on by Fraser Cain

Orionid Meteor Shower, October 21

Would you like to see a piece of Halley’s Comet streak past a planet that looks like an exploding star? No problem. Just set your alarm.

It’s going to happen, in plain view–no telescope required, on Thursday morning, Oct. 21st.

Go outside before sunrise, around 5:30 a.m. is best, and look east. The brightest object in that direction is the planet Venus. It looks like a star going supernova. Above Venus lies Saturn, and below, near the horizon, is Jupiter. Every 10 minutes or so you’ll see a meteor streak among these planets. The meteors are pieces of Comet Halley.

“Every year around this time Earth glides through a cloud of dusty debris from Halley’s Comet,” explains Bill Cooke of the NASA Marshall Space Flight Center. “Bits of dust, most no larger than grains of sand, disintegrate in Earth’s atmosphere and become shooting stars.”

“It’s not an intense shower,” he says, “but it is a pretty one.”

Astronomers call it the “Orionid meteor shower,” because the meteors appear to stream out of a point (called “the radiant”) in the constellation Orion. The radiant is near Orion’s left shoulder. But don’t stare at that spot, advises Cooke. Meteors near the radiant seem short and stubby, a result of foreshortening. Instead, look toward any dark region of the sky about 90 degrees away. The vicinity of Venus or Jupiter is good. You’ll see just as many Orionids there, but they will seem longer and more dramatic.

Framing the scene are several bright stars: Sirius, Regulus, Procyon and others. Pay special attention to Castor and Pollux in Gemini. They’re arranged in an eye-catching line with Saturn.

To sum it up in one word: “sparkling.” Two more words: “early” and “cold.” Or how about “worth waking up for?” You decide.

More about the Orionids
The Orionids are related to the eta Aquarids, a southern hemisphere meteor shower in May. Both spring from Halley’s Comet.

Earth comes close to the orbit of Halley’s Comet twice a year, once in May and again in October,” explains Don Yeomans, manager of NASA’s Near-Earth Object Program at the Jet Propulsion Laboratory. Although the comet itself is rarely nearby–it’s near the orbit of Neptune now–Halley’s dusty debris constantly moves through the inner solar system and causes the two regular meteor showers.

In 1986, the last time Comet Halley swung past the Sun, solar heating evaporated about 6 meters of dust-laden ice from the comet’s nucleus. That’s typical, say researchers. The comet has been visiting the inner solar system every 76 years for millennia, shedding layers of dust each time.

At first, the bits of dust simply follow the comet, which means they can’t strike our planet. Earth’s orbit and Halley’s orbit, at their closest points, are separated by 22 million km (0.15 AU). Eventually, though, the dust spreads out and some of it migrates until it is on a collision course with Earth.

“Particles that leave the nucleus evolve away from the orbit of the comet for two main reasons,” explains Yeomans. “First, gravitational perturbations caused by encounters with planets are different [for the dust and for the comet]. Second, dust particles are affected by solar radiation pressure to a far greater extent than the comet itself.”

“The orbital evolution of Halley’s dust is a very complicated problem,” notes Cooke. No one knows exactly how long it takes for a dust-sized piece of Halley to move to an Earth-crossing orbit — perhaps centuries or even thousands of years. One thing is certain: “Orionid meteoroids are old.”

They’re also fast. “Orionid meteoroids strike Earth’s atmosphere traveling 66 km/s or 148,000 mph,” he continued. Only the November Leonids (72 km/s) are faster. Sometimes fast meteors explode, and they leave glowing “trains” (incandescent bits of debris in their wake) that last for several seconds to minutes. These trains, blown by upper atmospheric winds into twisted and convoluted shapes, can be even prettier than the meteors themselves.

You never know what you might see, before sunrise, on a magical Thursday morning.

Original Source: Science@NASA Story

Posted on by Fraser Cain

Some Stars Take an Erratic Journey

A team of European astronomers has discovered that many stars in the vicinity of the Sun have unusual motions caused by the spiral arms of our galaxy, the Milky Way. According to this research, based on data from ESA’s Hipparcos observatory, our stellar neighbourhood is the crossroads of streams of stars coming from several directions. Some of the stars hosting planetary systems could be immigrants from more central regions of the Milky Way.

The Sun and most stars near it follow an orderly, almost circular orbit around the centre of our galaxy, the Milky Way. Using data from ESA’s Hipparcos satellite, a team of European astronomers has now discovered several groups of ‘rebel’ stars that move in peculiar directions, mostly towards the galactic centre or away from it, running like the spokes of a wheel. These rebels account for about 20% of the stars within 1000 light-years of the Sun, itself located about 25 000 light-years away from the centre of the Milky Way.

The data show that rebels in the same group have little to do with each other. They have different ages so, according to scientists, they cannot have formed at the same time nor in the same place. Instead, they must have been forced together. “They resemble casual travel companions more than family members,” said Dr Benoit Famaey, Universit? Libre de Bruxelles, Belgium.

Famaey and his colleagues believe that the cause forcing the rebel stars together on their unusual trajectory is a ‘kick’ received from one of the Milky Way’s spiral arms. The spiral arms are not solid structures but rather regions of higher density of gas and stars, called ‘density waves’ and similar to traffic hot-spots along the motorway. An approaching density wave compresses the gas it encounters and favours the birth of new stars, but it can also affect pre-existing stars by deflecting their motion. After the wave has passed, many stars will thus travel together in a stream, all in the same direction, even though they were originally on different trajectories or not even born.

This research has shown that the neighbourhood of the Sun is a crossroads of many streams, made up of stars with different origins and chemical composition. These streams could also account for many of the stars with planetary systems recently discovered near the Sun.

Astronomers know that stars with planetary systems preferentially form in dense gas clouds with a high metal content, such as those located in the more central regions of the Milky Way. The streams discovered by Hipparcos could be the mechanism that brought them closer to the Sun. As Famaey explains, “If these stars are kicked by a spiral arm, they can be displaced thousands of light-years away from their birthplace.” These stars, together with their planets, can thus have migrated closer to the Sun.

To learn more about the structure of our Milky Way, an aggregate of thousands of millions of stars, astronomers look at the way in which stars stay together in a coherent way or move with respect to the Sun and relative to one another. During its four-year mission, ESA’s Hipparcos satellite has measured the distance and motion of more than a hundred thousand stars within a 1000 light-years of the Sun. However, while Hipparcos’s data show in which directions stars are moving on the sky, they cannot tell whether stars are coming towards us or going away from us.

By combining the Hipparcos data with ground-based measurements of their ?Doppler shift?, obtained with a Swiss telescope at the Observatoire de Haute-Provence, France, Famaey and his colleagues could add the missing third dimension, namely the speed with which stars approach us or recede from us. Because of the Doppler shift, the colour of a star appears to change when it travels towards us or away from us, becoming respectively bluer or redder and giving astronomers information about its motion. “By combining all these first-class data, we now have a comprehensive, three-dimensional view of how nearby stars move about us,” said Famaey.

Scientists now wonder how widespread are the streams discovered by Famaey’s team and what role they could play in the evolution of our galaxy. “This result opens up exciting new prospects for our understanding of the dynamics of the Milky Way,” said Dr Michael Perryman, ESA Hipparcos and Gaia project scientist. ESA’s forthcoming mission Gaia, scheduled for launch in 2011, will make it possible to extend this investigation over a much wider region of our galaxy. Gaia will observe more than a thousand million stars and will measure their motion in all three dimensions simultaneously, thanks to the on-board spectrograph providing information on their Doppler shift. “This will give us the clearest view ever of the structure and evolution of the Milky Way,” Perryman said.

Original Source: ESA News Release

Posted on by Fraser Cain

Early Solar System Was a Mess

Planets are built over a long period of massive collisions between rocky bodies as big as mountain ranges, astronomers announced today.

New observations from NASA’s Spitzer Space Telescope reveal surprisingly large dust clouds around several stars. These clouds most likely flared up when rocky, embryonic planets smashed together. The Earth’s own Moon may have formed from such a catastrophe. Prior to these new results, astronomers thought planets were formed under less chaotic circumstances.

“It’s a mess out there,” said Dr. George Rieke of the University of Arizona, Tucson, first author of the findings and a Spitzer scientist. “We are seeing that planets have a long, rocky road to go down before they become full grown.”

Spitzer was able to see the dusty aftermaths of these collisions with its powerful infrared vision. When embryonic planets, the rocky cores of planets like Earth and Mars, crash together, they are believed to either merge into a bigger planet or splinter into pieces. The dust generated by these events is warmed by the host star and glows in the infrared, where Spitzer can see it.

The findings will be published in an upcoming issue of the Astrophysical Journal. They mirror what we know about the formation of our own planetary system. Recent observations from studies of our Moon’s impact craters also reveal a turbulent early solar system. “Our Moon took a lot of violent hits when planets had already begun to take shape,” Rieke said.

According to the most popular theory, rocky planets form somewhat like snowmen. They start out around young stars as tiny balls in a disc-shaped field of thick dust. Then, through sticky interactions with other dust grains, they gradually accumulate more mass. Eventually, mountain-sized bodies take shape, which further collide to make planets.

Previously, astronomers envisioned this process proceeding smoothly toward a mature planetary system over a few million to a few tens of millions of years. Dusty planet-forming discs, they predicted, should steadily fade away with age, with occasional flare-ups from collisions between leftover rocky bodies.

Rieke and his colleagues have observed a more varied planet-forming environment. They used new Spitzer data, together with previous data from the joint NASA, United Kingdom and the Netherlands’ Infrared Astronomical Satellite and the European Space Agency’s Infrared Space Observatory. They looked for dusty discs around 266 nearby stars of similar size, about two to three times the mass of the Sun, and various ages. Seventy-one of those stars were found to harbor discs, presumably containing planets at different stages of development. But, instead of seeing the discs disappear in older stars, the astronomers observed the opposite in some cases.

“We thought young stars, about one million years old, would have larger, brighter discs, and older stars from 10 to 100 million years old would have fainter ones,” Rieke said. “But we found some young stars missing discs and some old stars with massive discs.”

This variability implies planet-forming discs can become choked with dust throughout the discs’ lifetime, up to hundreds of millions of years after the host star was formed. “The only way to produce as much dust as we are seeing in these older stars is through huge collisions,” Rieke said.

Before Spitzer, only a few dozen planet-forming discs had been observed around stars older than a few million years. Spitzer’s uniquely sensitive infrared vision allows it to sense the dim heat from thousands of discs of various ages. “Spitzer has opened a new door to the study of discs and planetary evolution,” said Dr. Michael Werner, project scientist for Spitzer at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

“These exciting new findings give us new insights into the process of planetary formation, a process that led to the birth of planet Earth and to life,” said Dr. Anne Kinney, director of the universe division in the Science Mission Directorate at NASA Headquarters, Washington. “Spitzer truly embodies NASA’s mission to explore the universe and search for life,” she said.

JPL manages the Spitzer Space Telescope for NASA’s Science Mission Directorate. Artist’s concepts and additional information about the Spitzer Space Telescope is available at http://www.spitzer.caltech.edu.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Edge of Huygens Crater

This image, taken by the High Resolution Stereo Camera (HRSC) on board ESA?s Mars Express spacecraft, shows the eastern rim of the Martian impact crater Huygens.

The image was taken during orbit 532 in June 2004 with a ground resolution of approximately 70 metres per pixel. The displayed region is centred around longitude 61? East and latitude 14? South.

Huygens is an impact structure, about 450 kilometres wide, located in the heavily cratered southern highlands of Mars. Crater counts of the rim unit of the impact basin indicate that it is almost 4000 million years old.

This implies that this basin was formed in the early history of the planet and indicates a period of heavy bombardment in roughly the first 500 million years of the planet?s lifetime.

The basin shows an inner ring that has been subsequently filled by sediments transported into the crater.

Thia image showa part of the eastern rim of the crater. The rim is heavily eroded and shows a ?dendritic? pattern. This observation suggests surface water run-off.

Dendritic systems are the most common form of drainage system found on Earth. They consist of a main ?river? valley with tributaries with their own tributaries. From above, they look like a tree or a river delta in reverse.

The valley system is blanketed by dark material, which was either transported by a fluid running through the channels or by wind-driven (?aeolian?) processes. Part of the area has been covered by slightly redder material, which implies a different chemical composition.

Original Source: ESA News Release

Posted on by Fraser Cain

What’s Up This Week? – October 18 – 24

Monday, October 18 – For naked-eye observers, enjoy the beautiful Moon and be sure to gaze upon one of the finest of stars, Vega. Facing West at just after sundown, Vega is bright enough to shine even in the city and will appear just slightly below the zenith. The name Vega means “Falling Eagle” and it is the fifth brightest star in the sky. Enjoyed in either telescopes or binoculars, Vega has a wonderful bluish appearance and a lovely halo of spectra. This magnificent star holds a place in ancient legend and blossomed in our imaginations even more recently as it became the “star” of the movie “Contact”. As the western-most point of the “Southern Triangle”, Vega holds a special appeal for those born in the year 1977. Why? Because Vega is 27 light years away, the light you see from it tonight left the year you were born!

For telescope users, the Moon gives a wonderful opportunity tonight to study ancient the crater Posidonius. Its 84 km by 98 km (52 by 61 mile) expanse is easily seen in the most modest of optical instruments and it offers a wealth of detail in its eroded walls and 1768 meter (5800 ft.) central peak. Be sure to continue on southward from Posidonius to edge of Mare Serenitatis to view the Apollo 17 landing area!

Tuesday, October 19 – The Moon will try to overtake the skies tonight, but observers will turn their backs to it as they face north and look almost directly overhead for bright star, Deneb. Visible even under urban conditions, Deneb marks the “tail” of the constellation of Cygnus and is the northernmost star of the “Summer Triangle”. Although Deneb is around 1600 light years away, it is the 19th brightest star in the sky and also one of the most luminous. Did you know that it shines about 60,000 times brighter than our own Sun?!

For moon watchers tonight, we celebrate 35 years of space exploration as the Apollo 11 landing site now becomes visible. For telescopes and binoculars the landing area will be near the terminator at the southern edge of Mare Tranquillitatus. For those of you who would like a real challenge? Try spotting small craters Armstrong, Aldrin and Collins just east of easy craters Sabine and Ritter. No scope? No problem! Look at the Moon. The dark round area you see on the north eastern limb is Mare Crisium. The dark area below that is Mare Fecundatatis… Now look mid-way on the terminator for the dark area that is Mare Tranquillitatus.

We were there…

Wednesday, October 20 – Tonight is a wonderful chance for binoculars and small telescopes to study the Moon. Craters Aristotle and Eudoxus to the north will be easily apparent, along with the Caucasus and Apennine mountain range. For those of you looking for a slight telescopic lunar challenge? Then look no further than the Valles Alpes. More commonly known as the “Alpine Valley” this deep gash cut across the northern surface will be easily visible and the lighting conditions will be just right to explore its 1.6 km to 20.9 km (1-13 mile) wide and 177 km (110 mile) long expanse.

Don’t stay up too late, though, because the Orionid Meteor Shower is about to begin!

Thursday, October 21 – Be sure to be outdoors before dawn to enjoy one of the year’s most reliable meteor showers. The offspring of Comet Halley will grace the early morning hours as they return once again as the Orionid meteor shower. This dependable shower produces an average of 10-20 meteors per hour at maximum and the best activity begins before local midnight on the 20th; it’ll become more visible as the Moon sets, and reaches its best as Orion stands high to the south at about two hours before local dawn on the 21st.

Although Comet Halley has long since departed our Solar System, the debris left from its trail still remain scattered in Earth’s orbital pattern around the Sun allowing us to predict when this meteor shower will occur. We first enter the “stream” at the beginning of October and do not leave it until the beginning of November, making your chances of “catching a falling star” even greater! These meteors are very fast, and although they are faint, it is still possible to see an occasional “fireball” that leaves a persistent trail.

For best success, try to get away from city lights. Facing South/Southeast, simply relax and enjoy the stars of the Winter Milky Way. The “radiant”, or apparent point of origin, for this shower will be near the red giant Alpha Orionis (Betelguese), but meteors may occur from any point in the sky. You will make your meteor watching experience much more comfortable if you take along a lawn chair, blanket and a thermos of your favourite beverage.

Clouded out? Don’t despair. You don’t always need your eyes or perfect weather to meteor watch. By tuning an FM radio to the lowest frequency possible that does not receive a “clear signal”, you can practice radio meteor listening! An outdoor FM antenna pointed at the zenith and connected to your receiver will increase your chances, but it’s not necessary. Simply turn up the static and listen. Those hums, whistles, beeps, bongs, and occasional snatches of signals are our own radio signals being reflected off the meteor’s ion trail!

Pretty cool, huh?

Now, enjoy your day and be sure to take out your telescopes and have a look at the Moon tonight. One of the most sought-after and unusual features will be visible to small telescopes in the southern half of the Moon near the terminator – Rupes Recta! Also known as “The Straight Wall”, this 130 km (75 mile) long, 366 meter (1200 ft.) high feature slopes upward with the steepest angle on the lunar surface at 41 degrees. It will be a challenge under these lighting conditions, but look for triple ring craters Ptolemy, Alphonsus and Arzachel to guide you. The “Straight Wall” will appear as a very thin line stretching across the edge of Mare Nubium.

Friday, October 22 – Start your weekend with some lunar exploration as crater Copernicus becomes visible to even the most modest of optical aids. Small binoculars will see Copernicus as a bright “ring” about midway along the lunar dividing line of light and dark called the “terminator”. Telescopes will reveal its 97 km (60 mile) expanse and 120 meter (1200 ft.) central peak to perfection. Copernicus holds special appeal as it’s the aftermath of a huge meteoric impact! At 3800 meters (12,600 feet) deep, its walls are around 22 km (14 miles) thick and over the next few days, the impact ray system extending from this tremendous crater will become wonderfully apparent.

Saturday, October 23 – It’s a “Moon Gazer’s” weekend as our nearest astronomical neighbor continues to light up the night sky. Even from 383,000 km (238,000 miles) away! Don’t put away your telescopes and binoculars thinking there will be nothing to view, because one of the most “romantic” features on the lunar surface will be highlighted tonight.

The Sinus Iridium is one of the most fascinating and calming areas on the Moon. At around 241 km (150 miles) in diameter and ringed by the Juras Mountains, it’s known as the quiet name of “The Bay of Rainbows” but was formed by a cataclysm. Science speculates that a minor planet around 201 km (125 miles) in diameter once impacted our forming Moon with a glancing strike and the result of that impact caused “waves” of material to wash up to a “shoreline” forming this delightful C-shaped lunar feature. The effect of looking at a bay is stunning as the smooth inner sands show soft waves called “rilles”, broken only by a few small, impact craters. The picture is complete as Promentoriums Heraclides and LaPlace tower above the surface at 1800 meters (5900 ft.) and 3000 meters (9900 feet) respectively and appear as distant “lighthouses” set on either tip of Sinus Iridum’s opening.

Sunday, October 24 – Take the time tonight to once again return to the Moon and explore with binoculars or telescopes the area to the south around another easy and delightful lunar feature, the crater Gassendi. At around 110 km (70 miles) in diameter and 2010 meters (6600 feet) deep, this ancient crater contains a triple mountain peak in its center. As one of the most “perfect circles” on the Moon, the south wall of Gassendi has been eroded by lava flows over a 48 km (30 mile) expanse and offers a great amount of details to telescopic observers on its ridge and rille covered floor.

For those observing with binoculars? Gassendi’s bright ring stands on the north shore of Mare Humorum… An area about the size of the state of Arkansas!

Writing by Tammy Plotner

Posted on by Fraser Cain

Deep Impact Arrives in Florida

NASA’s Deep Impact spacecraft has arrived in Florida to begin final preparations for a launch on Dec. 30, 2004 . The spacecraft was shipped from Ball Aerospace & Technologies in Boulder , Colo. , to the Astrotech Space Operations facility located near the Kennedy Space Center .

“Deep Impact has begun its journey to comet Tempel 1,” said Rick Grammier, Deep Impact project manager at NASA’s Jet Propulsion Laboratory. “First to Florida , then to space, and then to the comet itself. It will be quite a journey and one which we can all witness together.”

The Deep Impact spacecraft is designed to launch a copper projectile into the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth. When this 820-pound “impactor” hits the surface of the comet at approximately 23,000 miles per hour, the 3-by-3 foot projectile will create a crater several hundred feet in size. Deep Impact’s “flyby” spacecraft will collect pictures and data of the event. It will send the data back to Earth through the antennas of the Deep Space Network. Professional and amateur astronomers on Earth will also be able to observe the material flying from the comet’s newly formed crater, adding to the data and images collected by the Deep Impact spacecraft and other telescopes. Tempel 1 poses no threat to Earth in the foreseeable future.

Today at Astrotech, Deep Impact is being removed from its shipping container, the first of the numerous milestones to prepare it for launch. Later this week, the spacecraft begins functional testing to verify its state of health after the over-the-road journey from Colorado . This will be followed by loading updated flight software and beginning a series of Mission Readiness Tests. These tests involve the entire spacecraft flight system that includes the flyby and impactor, as well as the associated science instruments and the spacecraft’s basic subsystems.

Next, the high gain antenna used for spacecraft communications will be installed. The solar array will then be stowed and an illumination test performed as a final check of its performance. Next, Deep Impact will be ready for fueling preparations. Once this is complete, the 2,152-pound spacecraft will be mated atop the upper stage booster, the Delta rocket’s third stage. The integrated stack will be installed into a transportation canister in preparation for going to the launch pad in mid-December.

Once at the pad and hoisted onto the Boeing Delta II rocket, a brief functional test will be performed to re-verify spacecraft state of health. Next will be an integrated test with the Delta II before installing the fairing around the spacecraft.

Deep Impact mission scientists are confident such an intimate glimpse beneath the surface of a comet, where material and debris from the formation of the Solar System remain relatively unchanged, will answer basic questions about the formation of the Solar System and offer a better look at the nature and composition of these celestial wanderers.

Launch aboard the Boeing Delta II rocket is scheduled to occur on Dec. 30, 2004 from Launch Complex 17 at Cape Canaveral Air Force Station. The launch window extends from 2:39 – 3:19 p.m. EST.

The overall Deep Impact mission management for this Discovery class program is conducted by the University of Maryland , College Park , Md. Deep Impact project management is by the Jet Propulsion Laboratory in Pasadena , Calif. The spacecraft has been built for NASA by Ball Aerospace and Technologies Corporation. The spacecraft/launch vehicle integration and launch countdown management are the responsibility of the Launch Services Program office headquartered at Kennedy Space Center .

Original Source: NASA News Release

Posted on by Fraser Cain

SMART-1 Nearly Captured By the Moon

Image credit: ESA
From 10 to 14 October the ion engine of ESA?s SMART-1 carried out a continuous thrust manoeuvre in a last major push that will get the spacecraft to the Moon capture point on 13 November.

SMART-1, on its way to the Moon, has now covered more than 80 million kilometres. Its journey started on 27 September 2003, when the spacecraft was launched on board an Ariane 5 rocket from Europe?s spaceport in Kourou, French Guiana. Since then, it has been spiralling in progressively larger orbits around Earth, to eventually be captured by the lunar gravity and enter into orbit around the Moon in November this year.

The SMART-1 mission was designed to pursue two main objectives. The first is purely technological: to demonstrate and test a number of space techniques to be applied to future interplanetary exploration missions. The second goal is scientific, mainly dedicated to lunar science. It is the technology demonstration goal, in particular the first European flight test of a solar-powered ion engine as a spacecraft?s main propulsion system, that gave shape to the peculiar route and duration (13 months) of the SMART-1 journey to the Moon.

The long spiralling orbit around Earth, which is bringing the spacecraft closer and closer to the Moon, is needed for the ion engine to function and be tested over a distance comparable to that a spacecraft would travel during a possible interplanetary trip. The SMART-1 mission is also testing the response of a spacecraft propelled by such an engine during gravity-assisted manoeuvres. These are techniques currently used on interplanetary journeys, which make use of the gravitational pull of celestial objects (e.g. planets) for the spacecraft to gain acceleration and reach its final target while saving fuel.

In SMART-1?s case, the Moon?s gravitational pull has been exploited in three ‘lunar resonance’ manoeuvres. The first two successfully took place in August and September 2004. The last resonance manoeuvre was on 12 October, during the last major ion engine thrust, which lasted nearly five days, from 10 to 14 October. Thanks to this final thrust, SMART-1 will make two more orbits around Earth without any further need to switch on the engine, apart from minor trajectory correction if needed. The same thrust will allow the spacecraft to progressively fall into the natural sphere of attraction of the Moon and start orbiting around it from 13 November, when it is 60 000 kilometres from the lunar surface.

SMART-1 will reach its first perilune (initial closest distance from the lunar surface) on 15 November, while the ion engine is performing its first and major thrust in orbit around the Moon. After that it will continue orbiting around the Moon in smaller loops until it reaches its final operational orbit (spanning between 3000 and 300 kilometres over the Moon?s poles) in mid-January 2005. From then, for six months Smart-1 will start the first comprehensive survey of key chemical elements on the lunar surface and will investigate the theory of how the Moon was formed.

Original Source: ESA News Release