Last Chance to See Space Shuttle Endeavour in Night Sky … Ever

NASA's space shuttle Discovery and the International Space Station are seen in this time-lapse image as they fly over Leiden, The Netherlands, just before the two spacecraft docked on March 17, 2009 during the STS-119 mission. The shuttle is the object slightly fainter and lower in the sky. Movement is from right to left
CREDIT: Marco Langbroek

With NASA's space shuttle Endeavour set to undock from the International Space Station late Sunday (May 29), skywatchers across much of the United States and southern Canada are in for a real treat: They'll have one last chance to see Endeavour in the night sky before the shuttle retires for good.

The best times to look for Endeavour and the space station will be before sunrise on Monday and Tuesday (May 30 and 31). Weather permitting, there should be opportunities to see both the Endeavour and space station flying across the sky from many locations.

The sight should easily be visible to anyone, even from brightly lit cities. Considering that after this shuttle mission there will be only be one left before the program ends (tentatively set for July 8), the view of a shuttle and the space station flying together will soon be a sight that will pass into history.

Endeavour is in the homestretch of its last mission, a 16-day trip to upgrade and resupply the space station. The shuttle launched into space from NASA's Kennedy Space Center in Florida on May 16. Endeavour and its six-astronaut crew are due to return to Earth June 1.

Other satellites visible too
The appearance of either the space shuttle or the space station moving across the sky is not in itself unusual. On any clear night within a couple of hours of local sunset or sunrise and with no optical aid, you can usually spot several orbiting Earth satellites creeping across the sky like moving stars.

Satellites become visible only when they are in sunlight and the observer is in deep twilight or darkness. This usually means shortly after dusk or before dawn.

What makes the prospective upcoming passages so interesting is that you'll be able to see the two largest orbiting space vehicles in the sky at the same time.

Endeavour will undock from the space station Sunday at 11:53 p.m. EDT (0353 May 30 GMT). Endeavour will fly around the space station before finally pulling away at 4:36 a.m. EDT (0836 GMT).

Monday morning, Endeavour should still be visible at a relatively close distance to the space station until its scheduled return to the Kennedy Space Center in Florida early Wednesday morning.

What you can see
Here's what you can expect to see if you have a clear view of the night sky and good weather:

On Monday, Endeavour and the space station will be traveling across North America on southwest-to-northeast trajectories and should appear as a pair of very "bright stars." The space station should appear as the noticeably brighter object and will be trailing Endeavour as they move across the sky.

Across much of the eastern half of the United States, the two spaceships will fly overhead at around 4:46 a.m. EDT, only about 10 minutes after Endeavour has begun maneuvering away from the space station. As a result, the two spacecraft will appear exceptionally close, separated by only about 7 arc minutes — roughly equal to only about one-quarter the apparent width of the moon.

Binoculars will certainly aid in visually separating the two. That narrow gap between the two will have significantly widened when Endeavour and the space station fly over the western United States, just over 90 minutes later.

And for all observers in the United States and southern Canada, the separation will have increased to 30 degrees or more by Tuesday morning. Your clenched fist held at arm's length measures roughly 10 degrees; so on Tuesday expect Endeavour and the station to separated by about "three fists."

A large telescope would be needed to make out details of the sprawling station. Traveling in their respective orbits at approximately 18,000 mph (29,000 kph), both should be visible anywhere for about one to five minutes (depending on the particular viewing pass) as they glide with a steady speed across the sky.

Because of its size and configuration of highly reflective solar panels, the space station is now, by far, the brightest man-made object currently in orbit around the Earth.

Astronomers measure the brightness of a sky object in terms of magnitude, a reverse scale in which the lower an object's number, the brighter it appears in the sky.

On favorable passes, the station approaches magnitude -5 in brightness, which would rival the planet Venus and is more than 25 times brighter than Sirius, the brightest star in the night sky. Some skywatchers can even catch a glimpse of the space station just before sunset or shortly after sunrise.

And as a bonus, sunlight glinting directly off the solar panels can sometimes make the space station appear to briefly flare in brilliance.

Region of visibility
Generally speaking, on the mornings of May 30 and 31, the tandem will be visible across parts of southern Canada as well as most of the 48 contiguous United States (Hawaii and Alaska, will not have favorable viewing passes during this upcoming week).

Across the northern half of the United States there will be two or three morning viewing opportunities. For some favored locations, like Philadelphia, Washington D.C. and Richmond there will be as many as four opportunities.

Over the southern United States, the viewing opportunities will be reduced to just one (on May 30). Places below latitude 30 degrees north will unfortunately be denied a view of the "dynamic duo" because they'll appear too low in the sky and too near to sunrise to be easily visible. From Florida, for example, Jacksonville will get a brief view on Monday morning, but the rest of the state will be shut out.

In contrast, some northern localities will be favored with exceptionally good views.

From St. Louis, for instance, the space station and Endeavour will appear to suddenly emerge from out of the Earth’s shadow on Monday morning at a very high altitude of 72 degrees (more than "seven fists") above the southeast horizon during a short 1-minute pass beginning at 3:47 a.m. CDT.

And on Tuesday morning, as seen from Providence, RI, Endeavour will appear about 30 degrees out in front of the space station as they each emerge from the Earth’s shadow about halfway up in the southwest sky at 3:38 a.m. EDT, taking two minutes to track to the northeast.

At their highest point, the two spacecraft will reach altitudes of 87 and 86 degrees respectively, passing virtually directly overhead.

Europe too!
Europeans will also be favored with views in their pre-sunrise skies.

Both spacecraft will still be docked and will appear as a single very bright "moving star" on Monday morning, but they’ll be widely separated by 25 or 30 degrees on Tuesday morning. Northern locations, such as London will get only one chance (on Tuesday morning), but locations farther south, such as Madrid and Rome, will get up to three opportunities during the Monday/Tuesday interval.

And like Providence, Madrid will have an opportunity to see a nearly overhead pass of both spacecraft on Tuesday morning beginning at 5:03 local time.

When and where to look

So what is the viewing schedule for your particular hometown? You can easily find out by visiting one of these three web sites:

* Chris Peat's Heavens Above
* NASA's SkyWatch
* Spaceweather.com

Each will ask for your zip code or city, and respond with a list of suggested spotting times. Predictions computed a few days ahead of time are usually accurate within a few minutes. However, they can change due to the slow decay of the space station's orbit and periodic reboosts to higher altitudes. Check frequently for updates.

Another great site is Real Time Satellite Tracking, which shows you what part of the Earth the space station or shuttle happen to be over at any given moment during the day or night.

Endeavour's STS-134 mission is NASA's second-to-last shuttle mission before the 30-year program is retired for good.Like its sister ships Discovery and Atlantis, Endeavour will eventually be put on public display as a museum piece.

Article by: Joe Rao, SPACE.com Skywatching Columnist
Source: Space.com

Four Planets Align Near Moon on Memorial Day Weekend

This sky map of the pre-dawn sky shows the Memorial Day alignment of four planets near the moon on Memorial Day weekend, Monday, May 30, 2011 at 5:30 a.m. local time in the United States.
CREDIT: Starry Night Software

The unusual month-long convergence of four planets in the pre-dawn sky is nearing an end, as the planets begin separating from each other and going their separate ways. But one final series of meetings is on tap for this Memorial Day weekend.

Between Sunday and Tuesday (May 29 and 31), the planets Jupiter, Venus, Mars and Mercury will appear in a grouping with a bonus visitor: the moon. Weather permitting, skywatchers can look low to the east-northeast horizon about a half hour before sunrise and see the four planets arrayed in a line.

The sky map of the four planets here shows how they will appear from mid-northern latitudes in North America on Monday (May 30).

Your clenched fist held at arm’s length measures roughly 10 degrees of the sky, and the planetary alignment will stretch across 20 degrees. So the four planets will be stretched out over a portion of the sky measuring about "two fists" in length.

To see or not to see
But actually seeing all four planets is something else altogether. Those blessed with clear skies will certainly see Jupiter, hovering about 15 degrees above the horizon almost due east.

Shining about twice as bright as the brightest star in the sky (Sirius), Jupiter can be easily seen through the bright morning twilight as a silvery, non-twinkling "star."

Much farther down to Jupiter's lower left will shine an even more brilliant planet: Venus, which has been a dominant object in the morning sky since last November, but in recent weeks, has dropped very low into the pre-sunrise glow. Only its great brightness (it shines about five times brighter than Jupiter) allows it to still be seen despite its low altitude and the bright sky background.

If you have binoculars, scan that part of the sky a few degrees above and to the right of Venus and you might run across Mars, a yellow-orange starlike object shining only about one-hundredth as bright as Venus.

Lastly, below and to the left of Venus is Mercury, which although shining much brighter than Mars, probably will not be visible even in binoculars because of its very low altitude – only 2 degrees above the horizon.

Those who live south of the equator, where the planets have been climbing higher in the eastern sky and rising in a darker sky, all four planets have been putting on a great show all during May and will continue to be well seen into the final days of this month.

Enter the moon
As for the moon, early on Sunday morning, you'll see it as a delicate crescent, a slender sliver about 11 percent illuminated, hovering five degrees above and just to the left of Jupiter. The two will make for a very pleasing scene in the brightening dawn sky.

On Monday morning, the crescent will appear about half as thin (about 6 percent illuminated ) and only about half as high up as on Sunday. It will have moved far off to Jupiter's left, but will still be high above and to the right of Venus.

The real challenge comes on Tuesday morning, when the crescent will have shrunk to a mere hairline, just 2 percent illuminated. It will then be only about 36 hours from new phase, and 5 degrees to the left of Venus.

You may need binoculars to pick up the moon in the bright twilight glow.

Where do we go from here?
Jupiter will continue rising several minutes earlier each morning, slowly getting higher and more prominent in the days to come in the morning sky.

On the other hand, Venus has been slipping slowly down into the sunrise fires. It should still be visible for another five or six weeks, albeit very low to the east-northeast horizon about a half hour before sunrise before finally disappearing into the sun's glare for the summer.

Mars, like Jupiter is moving away from the sun, although more slowly; don't expect to readily see it in the morning sky until sometime during July. By August, it will be an easy object to see, rising before the break of dawn.

And little Mercury will rapidly sweep into obscurity in the coming days, passing behind the sun (called a superior conjunction) on June 12 and reappearing early in July for evening viewers.

Article by: Joe Rao, Space.com Skywatching Columnist
Source: Space.com

Rescuers race to find survivors of Joplin tornado

JOPLIN, Mo. – Rescue crews dug through piles of splintered houses and crushed cars Monday in a search for victims of a half-mile-wide tornado that killed at least 116 people when it blasted much of this Missouri town off the map and slammed straight into its hospital.

It was the nation's deadliest single twister in nearly 60 years and the second major tornado disaster in less than a month.

Authorities feared the toll could rise as the full scope of the destruction comes into view: house after house reduced to slabs, cars crushed like soda cans, shaken residents roaming streets in search of missing family members. And the danger was by no means over. Fires from gas leaks burned across town, and more violent weather loomed, including the threat of hail, high winds and even more tornadoes.

At daybreak, the city's south side emerged from darkness as a barren, smoky wasteland.

"I've never seen such devastation — just block upon block upon block of homes just completely gone," said former state legislator Gary Burton who showed up to help at a volunteer center at Missouri Southern State University.

Unlike the multiple storms that killed more than 300 people last month across the South, Joplin was smashed by just one exceptionally powerful tornado.

Not since a June 1953 tornado in Flint, Mich., had a single twister been so deadly. That storm also killed 116, according to the National Weather Service.

Authorities were prepared to find more bodies in the rubble throughout this gritty, blue-collar town of 50,000 people about 160 miles south of Kansas City.

Gov. Jay Nixon told The Associated Press he did not want to guess how high the death toll would eventually climb. But he said: "Clearly, it's on its way up."

Seventeen people were pulled alive from the rubble. An unknown number of people were hurt.

While many residents had up to 17 minutes of warning, rain and hail may have drowned out the sirens.

Larry Bruffy said he heard the first warning but looked out from his garage and saw nothing. "Five minutes later, the second warning went off," he said. "By the time we tried to get under the house, it already went over us."

As rescuers toiled in the debris, a strong thunderstorm lashed the crippled city. Rescue crews had to move gingerly around downed power lines and jagged chunks of debris as they hunted for victims and hoped for survivors. Fires, gas fumes and unstable buildings posed constant threats.

Teams of searchers fanned out in waves across several square miles. The groups went door to door, making quick checks of property that in many places had been stripped to their foundations or had walls collapse.

National Weather Service Director Jack Hayes said the storm was given a preliminary label as an EF4 — the second-highest rating assigned to twisters based on the damage they cause.

Hayes said the storm had winds of 190 to 198 mph. At times, it was three-quarters of a mile wide.

Some of the most startling damage was at St. John's Regional Medical Center, where staff had only moments to hustle their patients into the hallway. Six people died there, five of them patients, plus one visitor.

The storm blew out hundreds of windows and caused damage so extensive that doctors had to abandon the hospital soon after the twister passed. A crumpled helicopter lay on its side in the parking lot near a single twisted mass of metal that used to be cars.

Dr. Jim Riscoe said some members of his emergency room staff showed up after the tornado with injuries of their own, but they worked through the night anyway.

"I spent most of my life at that hospital," Riscoe said at a triage center at Joplin's Memorial Hall entertainment venue. "It's awful. I had two pregnant nurses who dove under gurneys ... It's a testimony to the human spirit."

Once the center of a thriving mining industry, Joplin flourished though World War II because of its rich lead and zinc mines. It also gained fame as a stop along Route 66, the storied highway stretching from Chicago to Santa Monica, Calif., before freeways diminished the city's importance.

The community, named for the founder of the area's first Methodist congregation, is now a transportation crossroads and manufacturing hub. It's also the hometown of poet Langston Hughes and "Gunsmoke" actor Dennis Weaver.

Major employers in and around the city include electronics manufacturer LaBarge Inc., colleges such as Missouri Southern State University and hospitals and clinics. Agriculture is also important to the economy.

As the tornado bore down on their trailer home, Joshua Wohlford, his pregnant girlfriend and their two toddlers fled to a Walmart store. The family narrowly escaped after a shelf of toys partially collapsed, forming a makeshift tent that shielded them.

"It was 15 minutes of hell," Wohlford said.

At a Fast Trip convenience store, another 20 people ran into a pitch-black cooler as the building began to collapse around them. They documented their experience with a video that was drawing tens of thousands of views online by Monday afternoon. The audio was even more terrifying than the imagery — earsplitting wind, objects getting smashing, wailing children and a woman praying repeatedly.

Brennan Stebbins said the group crouched on the floor, clinging to and comforting each other until they were able to crawl out. No one was seriously hurt.

Shielded by mattresses, former lawmaker Chuck Surface rode out the storm in his basement with his wife, daughter, granddaughter and dog. After about five minutes, the deafening roar abruptly stopped.

"When it got to where we thought we could look out," he said, "we went to the top of the stairs and there was no roof — it was all open air."

Dazed survivors tried to salvage clothes, furniture, family photos and financial records from their flattened or badly damaged homes.

Kelley Fritz rummaged briefly through what was left of a storage building, then gave up. Her boys, both Eagle Scouts, rushed into the neighborhood after realizing every home was destroyed.

When they returned, she said, "my sons had deceased children in their arms."

Others just waited for answers.

Justin Gibson stood outside the tangled remains of a Home Depot and pointed to a black pickup that had been tossed into them. It belonged to his roommate's brother, last seen at the store with his two young daughters.

"I don't know the extent of this yet," Gibson said, "but I know I'll have friends and family dead."

Last month, a ferocious pack of twisters roared across six Southern states, killing more than 300 people, more than two-thirds of them in Alabama.

As in the Midwest, the Southerners also had warning — as much as 24 minutes. But those storms were too wide and too powerful to escape. They obliterated entire towns from Tuscaloosa, Ala., to Bristol, Va., in what the weather service said was the nation's deadliest tornado outbreak since April 1974.

"This was one tornado," said Greg Carbin, warning specialist with the Storm Prediction Center in Norman, Okla. "It was not the same type of large-scale outbreak."

It did, however, get the attention of those who suffered in the South.

"We're praying for those people," said retired Marine Willie Walker, whose Tuscaloosa home suffered more than $50,000 in damage. "We know what they're going through because we've been there already."

Forecasters said severe weather would probably persist all week. Arkansas, Kansas, Missouri and Oklahoma could see tornadoes through Tuesday, and the bad weather could reach the East Coast by Friday.

The twister that hit Joplin was one of more than 50 reported across seven Midwest states over the weekend. One person was killed in Minneapolis and another in Kansas, but Missouri took the hardest hits.

Triage centers and shelters around Joplin rapidly filled to capacity. At a Lowe's home-improvement store, wooden planks served as cots.

Kerry Sachetta, principal of a flattened Joplin High School, could barely recognize his own building.

"You see pictures of World War II, the devastation and all that with the bombing," he said. "That's really what it looked like."

___
Associated Press Writer David A. Lieb in Jefferson City contributed to this report.

Article by: Alan Scher Zagier and Jim Salter, Associated Press
Source: Yahoo! News

Jupiter's Moon Shadows Move Like Clockwork

On the morning of Wed, May 25, 2011 the moons Io and Europa and their shadows will cross the face of Jupiter.
CREDIT: Starry Night Software

Did you know that there is a gigantic and extremely accurate clock with four "hands" in our solar system? And that you can watch this clock on nearly any clear night?

The cosmic timepiece is created by Jupiter's four largest moons — Io, Europa, Ganymede and Callisto, which behave like hands on a clock with the gas giant planet at the center. As the moons cross Jupiter's face, they create shadows visible in telescopes, and skywatchers have a chance to spot this moon shadow play on May 25.

The Jupiter clock was discovered by Italian astronomer Galileo Galilee in 1609 when he first turned his newly constructed telescope toward the planet.

The Jupiter clock
Like the hands of any good clock, the four Galilean moons of Jupiter travel around the planet with extreme accuracy.

When the Jovian moons are off to the side of Jupiter, they are easy to see in the smallest of amateur telescopes as tiny bright points of light. When they pass directly in front of Jupiter, they almost vanish against the bright background of the planet.

When the sun, as seen from Earth, is off to the side, the moons cast their shadows on the face of Jupiter, causing eclipses. Although these shadows are very small, they are also very dark and can be seen in medium-size telescopes with at least a 90mm aperture.

Because the volcanic moon Io whizzes around Jupiter once every 1.8 Earth days, its shadow is the one most commonly seen. Europa takes 3.5 days to complete the circuit, so its shadow is seen less often.

Ganymede's shadow is rarer still, and at present, Callisto's shadow misses Jupiter entirely.

Because Europa's period is almost exactly twice that of Io, they often line up to cause "double features."

The Jupiter window
With Jupiter's satellites spinning around the planet so quickly, you'd think we’d often see these shadows. However, each shadow takes only an hour or so to cross Jupiter, and the planet itself is visible for only a brief period every day.

This is especially true this early in the apparition, when we catch only brief glimpses of Jupiter between when it rises high enough to clear the turbulence in Earth's atmosphere and when the sun floods our sky with light.

In late May this "window" opens briefly around 5:30 a.m. local time. The exact times vary from location to location; any planetarium program will let you narrow it down. Here are some examples from different locations in the United States:

Jupiter and its transiting moons are only visible for a brief time in Late May 2011.
CREDIT: Starry Night Education

As you can see, the farther north you are, the "narrower" your window is. In Florida, it's 50 minutes long. In Amarillo, nearly half an hour, and in Seattle, none at all. The sun rises over Seattle nine minutes before Jupiter would be high enough to observe.

Fortunately, a double transit takes quite a while to unfold, so even if you have a limited window, you may still see part of the show.

Jupiter phenomena
As mentioned earlier, this "clock" is very accurate, so the “phenomena” of Jupiter’s satellites can be calculated far in advance, and tables are available in the RASC Observer’s Handbook and on the Internet.

The first of the current series of double transits is not visible from North America, but the second in the series will be, on Wednesday, May 25. What you have happening is two satellites, Io and Europa, passing in front of Jupiter, casting their shadows ahead of them.

The timings of the series of events are as follows (times are usually given in Universal Time, but are converted to major time zones below):

Io and Europa transit Jupiter on May 25, 2011.
CREDIT: Starry Night Education

If this seems confusing to you, think of two dancers, Io and Europa, entering from the left side of a stage, with a light to their left casting their shadows on the stage backdrop. The shadows enter first, then the performers. At the end of the scene, the shadows leave first, followed by the performers.

If you match up the times of the events with the observing windows above, you’ll see that an observer in any part of the country sees only part of the show.

Observers on the eastern seaboard will see only the beginning; those on the West Coast will see only the end. Those in the middle will see most of the show.

Article by: Geoff Gaherty, Starry Night Education
Source: Space.com

Lonely Rogue Worlds Surprisingly Outnumber Planets with Suns

Artist's concept showing a free-floating planet with roughly the mass of Jupiter. These lone worlds, perhaps ejected from the planetary systems of their birth, are probably more common in our galaxy than stars.
CREDIT: NASA/JPL-Caltech/R. Hurt

Astronomers have discovered a whole new class of alien planet: a vast population of Jupiter-mass worlds that float through space without any discernible host star, a new study finds.

While some of these exoplanets could potentially be orbiting a star from very far away, the majority of them most likely have no parent star at all, scientists say.

And these strange worlds aren't mere statistical anomalies. They likely outnumber "normal" alien planets with obvious parent stars by at least 50 percent, and they're nearly twice as common in our galaxy as main-sequence stars, according to the new study.

Astronomers have long predicted the existence of free-flying "rogue alien planets." But their apparent huge numbers may surprise many researchers, and could force some to rethink how the planets came to be.

"Previous observations of bound planets tell us only about planets which are surviving in orbits now," said study lead author Takahiro Sumi, of Osaka University in Japan. "However, [these] findings inform us how many planets have formed and scattered out."

Alien worlds under gravitational lens
Sumi and his colleagues made the find using a method called gravitational microlensing, which watches what happens when a massive object passes in front of a star from our perspective on Earth. The nearby object bends and magnifies the light from the distant star, acting like a lens.

This produces a "light curve" — a brightening and fading of the faraway star's light over time — whose characteristics tell astronomers a lot about the foreground object's size. In many cases, this nearby body is a star; if it has any orbiting planets, these can generate secondary light curves, alerting researchers to their presence.

Before the current study, astronomers had used the gravitational microlensing technique to discover a dozen or so of the nearly 550 known alien planets. (NASA's Kepler mission has detected 1,235 candidate planets by a different method, but they still need to be confirmed by follow-up observations.)

Sumi and his team looked at two years' worth of data from a telescope in New Zealand, which was monitoring 50 million Milky Way stars for microlensing events. They identified 474 such events, including 10 that lasted less than two days.

The short duration of these 10 events indicated that the foreground object in each case was not a star but a planet roughly the mass of Jupiter. And the signals from their parent stars were nowhere to be found.

Independent observations from a telescope in Chile backed up the finds. Either these 10 planets orbit very far from their host stars — more than 10 times the Earth-sun distance — or they have no host stars at all, researchers said.

Common throughout the galaxy
Gravitational microlensing events are rare, because they require the precise alignment of a background star, a massive foreground object and Earth. So the discovery of 10 short-duration events in two years suggests a huge population of these unbound or distantly orbiting Jupiter-mass exoplanets throughout the galaxy, researchers said.

Sumi and his team calculated, in fact, that these planets are probably almost twice as common in our own Milky Way as main-sequence stars. And they likely outnumber "normal" planets with known host stars by more than 50 percent.

Other studies have established that it's probably pretty rare for huge planets to orbit more than 10 Earth-sun distances from a parent star. So the research team argues that most of the Jupiter-mass planets — at least 75 percent of them — are likely true "rogues," floating through space unbound to a star.

Theory predicts that such rogues should exist throughout the galaxy, and other researchers have found evidence of unbound objects that may indeed be orphan planets. But those worlds were much bigger, from three to 10 times Jupiter's mass, and there's a lot of uncertainty in the measurements.

Many of the previously detected objects could actually be "failed stars" known as brown dwarfs, Sumi said.

Sumi and his colleagues report their results in the May 19 issue of the journal Nature.

Rethinking planetary formation theories
The newly discovered rogue planets may have formed close to a host star, then been ejected from their solar systems by the gravitational influence of a huge neighbor planet, researchers said. Indeed, such planet-planet interactions are thought to be responsible for the odd, extremely close-in orbits of the giant alien planets known as "hot Jupiters."

But the abundance of the seemingly starless worlds may force astronomers to rethink some of their ideas about planet formation, according to Sumi.

The "current most recognized planetary formation theory (core accretion model) cannot create so many giant planets," Sumi told SPACE.com in an email interview. "So we need a different theory to create [so] many giant planets, such [as the] gravitational instability model."

In the core accretion model, dust coalesces to form a solid core, which later accretes gas around it, creating a planet. The gravitational instability model invokes the rapid collapse of gas, with a core forming later due to sedimentation.

The new study should inspire much follow-up research. One of the next steps could involve training more instruments on the microlensing alien planets, further monitoring them for any signs of a parent star. Such work, which may take years, could eventually reveal how many of these worlds actually do have parent stars, and how many are true rogues.

"The implications of this discovery are profound," astronomer Joachim Wambsganss, of Heidelberg University, wrote in an accompanying essay in the journal Nature. "We have a first glimpse of a new population of planetary-mass objects in our galaxy. Now we need to explore their proper­ties, distribution, dynamic states and history."

Source: Space.com

Mercury, Venus, Mars & Jupiter Converge in Night Sky

In May and June 2011, four planets will converge in the night sky.
CREDIT: Starry Night Software

During this month of May, four bright planets will engage in a fascinating dance with each other in the morning sky.

Mercury, Venus, Mars and Jupiter will be involved in a series of conjunctions, joined at the end of the month by a very thin, waning crescent moon. We could even refer to this as a "celestial summit meeting," or more precisely, a series of summit meetings during May 2011.

Twice during May three planets will converge to form a "trio."

According to Belgian calculator Jean Meeus, a trio is when three planets fit within a circle with a minimum diameter of 5 degrees. Such a limit was one that Meeus chose more or less arbitrarily, but as he notes, "We have to make a choice."

On Wednesday (May 11), Mercury, Venus and Jupiter will converge within 2.05-degrees of each other, followed just 10 days later by another trio, this time formed by Mercury, Venus and Mars, which will crowd within a 2.13-degree circle. Then late in the month, on three successive mornings, May 29th, 30th, and 31st, the waning crescent moon will arrive, sweeping past Jupiter, Mars, Venus and Mercury stretched out across the eastern sky from upper right to lower left.

Evil omen? Impending disaster?

What might ancient sky watchers from 500 or 1,000 years ago have ascribed to such a series of gatherings as this?

Most likely, they would have felt a mixture of fear and wonder. A fine example was a case in 1186 A.D. when an unusual gathering of the five planets visible to the naked eye resulted in a near-panic across the whole of Europe after religious leaders predicted that worldwide disasters would result!

Even today, in our modern world, similar fears sometimes arise.

You need only Google-search the date May 5, 2000, and you will find a number of different websites that predicted a variety of disasters attributed to the combined gravitational and tidal forces associated with a gathering of the sun, moon, Mercury, Venus, Mars, Jupiter and Saturn.

One website proclaimed that it would be "one of the most exciting, powerful and transformative celestial events of our millennium according to astronomy and astrology experts."

In many ways, these words sound all too similar to the hype and tripe that has been bandied about during these past few years concerning the Mayan Long Count calendar in 2012.

Needless to say, we all survived the recent 2000 celestial summit and despite what you might hear or read in the coming days ahead, absolutely nothing cataclysmic will take place (at least nothing that can be directly attributed to this impending dawn gathering of the moon and planets).

Tough to see

The only tragedy regarding this display is that those living north of the equator will have a difficult time seeing it.

At first glance there doesn't appear to be any problem concerning the visibility of these objects. Their elongations from the sun will range from 18 degrees to 26 degrees, which should place them all in dark skies. Unfortunately, during May, as seen especially from mid-northern latitudes, the ecliptic is oriented at a shallow angle relative to the eastern horizon at dawn.

As a result, the moon and planets will rise into view during late twilight and will lie very low to the east-northeast horizon by sunrise. To see them, you'll have to make sure not to have any potential obstructions to your visibility such as trees or buildings in that direction.

But coming above the horizon so near to sunrise will also mean that you'll have a fighting chance of catching only Venus (magnitude -4) and Jupiter (magnitude -2) with unaided eyes. Whether you will be able to glimpse zero-magnitude Mercury is debatable, and certainly binoculars will be needed if you have any hope of seeing Mars (magnitude +1).

The crescent moon will also prove to be a visual challenge, being only 2 percent illuminated on May 31. Low-lying clouds or haze near the horizon on any given morning will only reduce your chances of success.

In contrast, those of our SPACE.com readers in the Southern Hemisphere, where the ecliptic at dawn appears at a somewhat steeper angle, will see this ever-changing array somewhat higher and in a somewhat darker sky; more like mid-twilight as opposed to late twilight in the north.

Indeed, those living in far southern locations such as Cape Town, South Africa; Melbourne, Australia; or Dunedin, New Zealand, will have a much better chance of seeing and enjoying this month-long dance of the planets.

Article by: Joe Rao, SPACE.com Skywatching Columnist
Source: Space.com

Meteor Shower Tonight to Rain Bits of Halley's Comet on Earth

Bits and pieces of the famous Halley's Comet will light up the overnight sky in a promising meteor shower, weather permitting, skywatching experts say.

The annual Eta Aquarid meteor shower will peak early tomorrow morning (May 6) and is expected to put on a dazzling display of "shooting stars" for skywatchers graced with good weather and clear skies. That's because the moon, which is currently in its unlit new phase, won't interfere with the meteor light show as it did with last month's Lyrid shower.

The Eta Aquarids are meteors created by bits of left over material from Halley's Comet as it travels through the solar system on its 76 year orbit. This year, the display runs from April 28 through May 21, but May 6 should mark its peak, according to the American Meteor Society.

"Under ideal conditions (a dark, moonless sky) about 30 to 60 of these very swift meteors can be seen per hour," advises SPACE.com skywatching columnist Joe Rao. "And with a new moon on May 3 this is one of those years when observing conditions will be perfect."

This sky map of the Eta Aquarid meteor shower shows where the meteors will appear to originate from during their display. The best time to see them will be early Friday morning before 2 a.m. and 3 a.m. Local Time.

The Earth passes through the comet Halley's debris trails twice a year – once in May, and again in October – offering an appetizer for the comet's next trip through the inner solar system in 2061. Halley's comet last swung by in 1986.

NASA scientists say that the combination of the Eta Aquarid meteor shower and lack of moonlight should offer a rare chance for avid meteor-hunting skywatchers.

"This is your one chance this year to see meteors blaze across the sky without glaring moonlight dimming them," said NASA astronomer Bill Cooke, a member of the Space Environments team at the Marshall Space Flight Center in Huntsville, Ala., in a statement.



Here's how to see the Eta Aquarid meteor shower created by Halley's Comet, according to NASA:

The Eta Aquarid meteors appear to radiate out of the east-southeastern sky in the constellation Aquarius. But according to Cooke, you don't have stare in the constellation's direction to see the meteors.

"Meteors can appear in any part of the sky," Cooke explained. "In fact their trails will tend to point back toward the radiant, so if you look that way the meteor may appear somewhat stubby. They'll appear much longer going by you than coming at you."

If you have a dark, wide view of the night sky, you should be able to see some meteors by just lying down and gazing upwards. A good blanket or a comfortable outdoor chair is useful for long skywatching vigils.

"Eta Aquarids are fast, moving at 66 km/s (148,000 mph), and often trace long paths across the sky, sometimes leaving glowing, persistent trains," Cooke said. "In the Northern Hemisphere, depending on your latitude [the closer to the equator the better], you should see from 10 to 40 meteors just before dawn."

Article by: Tariq Malik, SPACE.com Managing Editor
Source: Space.com

Meteor Shower Spawned by Halley's Comet Peaks Friday

An image of Halley's Comet taken in 1986.
CREDIT: NASA

It has been 25 years since Halley's Comet last passed through the inner solar system, but an annual meteor shower keeps the icy wanderer's legacy on Earth alive this week.

Halley's Comet takes roughly 75 years to circle the sun, but if you're 30 years old or younger, you either have little or no memory of this famous cosmic vagabond's 1986 trip by Earth. And your next chance will come in the summer of 2061.

But if you don’t want to wait until 2061, you might want to step outside before sunrise during these next few mornings and try to catch a view of some "cosmic litter" that has been left behind in space by Halley's comet — a summer display of "shooting stars". [Video: Meteors from Halley's Comet]

The orbit of Halley's Comet closely approaches the Earth's orbit at two places, creating a rain of striking meteors for skywatchers during both instances. One point is in the middle to latter part of October, producing a meteor display known as the Orionids. The other point comes now, in early May, producing the annual Eta Aquarids meteor shower.

When and where to watch

The Eta Aquarid meteor shower is predicted to peak early Friday morning (May 6).

Under ideal conditions (a dark, moonless sky) about 30 to 60 of these very swift meteors can be seen per hour. And with a new moon on May 3 this is one of those years when observing conditions will be perfect. The shower appears at about one-quarter peak strength for about three or four days before and after May 6. [Spectacular Leonid meteor shower photos]

There is, however, a drawback if you plan to watch for these meteors this year — at least for those watching from north of the equator.

The radiant (the emanation point of these meteors) is at the "water jar" of the constellation Aquarius, which comes above the southeast horizon around 3 a.m. local daylight time, never gets very high as seen from north temperate latitudes, so the actual observed rates are usually much lower than the oft-quoted 30 to 60 meteors per hour.

From North America, typical rates are 10 meteors per hour at 26-degrees north latitude (Brownsville, Texas; Naples, Fla.), half of this at 35-degrees latitude (Albuquerque, N.M.; Chattanooga, Tenn., and practically zero north of 40 degrees (Philadelphia, Penn.; Salt Lake City, Utah).

Catch an 'Earthgrazer'

For most, perhaps the best hope is perhaps catching a glimpse of a meteor emerging from the radiant that will skim the atmosphere horizontally — much like a bug skimming the side window of an automobile. Meteor watchers call such shooting stars "Earthgrazers." They leave colorful, long-lasting trails.

"These meteors are extremely long," said Robert Lunsford, of the International Meteor Organization. "They tend to hug the horizon rather than shooting overhead where most cameras are aimed."

"Earthgrazers are rarely numerous," advises Bill Cooke, a member of the Space Environments team at the Marshall Space Flight Center. "But even if you only see a few, you're likely to remember them."

Comet crumbs

If you do catch sight of one early these next few mornings, keep in mind that you'll likely be seeing the incandescent streak produced by material that originated from the nucleus of Halley's comet.

When these tiny bits of comet collide with Earth, friction with our atmosphere raises them to white heat and produces the effect popularly referred to as "shooting stars."

So it is that the shooting stars that we have come to call the Eta Aquarids are really an encounter with the traces of a famous visitor from the depths of space and from the dawn of creation.

Article by: Joe Rao
Source: Space.com