Tag Archives: stars

Look Up: Milky Way Galaxy at its Best in July

Look-up-milky-way-galaxy-at-its-best-in-july-a161920c35

It’s possible that most people on Earth have never seen the Milky Way, the galaxy in which we live. The Milky Way used to be a part of every human’s life experience, but now that the majority of mankind lives in cities, with their light pollution, the Milky Way is rarely seen.

Our Milky Way galaxy is at its best for the next couple of weeks, but most of you will need to make a special effort to see it. It will probably require a drive of an hour or more to reach a dark enough location, where the Milky Way will be visible. Then it will require another 20 minutes for your eyes to become adjusted to the dark.

What will you see? Not the brilliant array of stars you see in photographs made with long exposures. The real Milky Way looks like a faint band of moonlit cloud arcing across the sky. Your eyes cannot resolve it into individual stars.

No one knew it was made up of stars until Galileo first turned his telescope on it in 1609 — this was one of his major discoveries. It wasn’t until a couple of centuries later that astronomers began to realize that this band of stars was in fact the local version of the “spiral nebulae” that astronomers were discovering all over the sky. [Our Milky Way Galaxy Explained (Infographic)]

The final clue to the puzzle was the realization that stars were all grouped into huge islands called galaxies, each containing many billions of stars. The Milky Way is our local galaxy.

Even today, beginners in astronomy often get confused by the two meanings of “Milky Way.” It can be used in its original sense to refer to the faint band of glow arching across the sky, or in its modern sense referring to the galaxy in which the sun resides.

Seeing the Milky Way

When amateur astronomers refer to the Milky Way, they usually refer to the faint band in the sky, although any time you look anywhere in the sky, all the stars you see are part of the Milky Way because we are in the Milky Way.

To see what the ancients called the Milky Way, you must first find a truly dark location. The maps on this web site show the areas in the world with the brightest and darkest sky. If like most people on Earth you live in a city, you can probably identify it as one of the white splotches. Use the maps to identify a green, blue, or black location near you — that’s where you must go if you want to find the Milky Way. [Best Telescopes for Night Sky Beginners (Reviews)]

But wait! Don’t try to spot the Milky Way tonight, because there is still an almost full moon in the sky. Wait a few nights until the moon has moved on in its monthly trip around the Earth.

When you get to your dark night sky, you may still need to block any nearby lights from your view. Then you will need to wait about 20 minutes for your eyes to adapt to the dark. Then, look towards the south in the sky.

If you live in the Northern Hemisphere, the center of the Milky Way will be low in the southern sky, and the band of the Milky Way will sweep upwards in an arch across the eastern sky to the northern horizon. If you live in the Southern Hemisphere, the center of the Milky Way will be almost overhead, and the band will sweep from your sothwestern horizon to your northeastern horizon.

Look for a faint silvery or milky cloud. Some parts will be brighter than others, giving a faintly mottled effect. These are star clouds, concentrations of millions of stars too faint to see as individual stars. You may also see some “holes” in the Milky Way: clouds of interstellar dust blocking our view of the stars beyond.

If you have a small binocular with you, say a 7×50 or 10×50, you can recreate Galileo’s discovery that stars make up the “glow” of the Milky Way. Even that small amount of magnification will be enough to resolve the Milky Way into thousands of stars.

What to See in the Milky Way Galaxy

Start your tour of the Milky Way by looking for the constellations Scorpius and Sagittarius. Unlike many constellations, these form clearly recognizable patterns.

Scorpius looks like the scorpion it’s named for, complete with long curving tail with stinger at the end. Its heart is marked by the red giant star Antares. Sagittarius looks nothing like a centaur archer, but rather like a prosaic teapot, complete with handle, spout, and lid. If you live in the north, you will find these low in the southern sky. If you live in the south, they will be almost overhead.

Because the center of the Milky Way is the richest part of the sky, it is crammed with nebulas and open star clusters. To give you some idea of this richness, the chart shows the names of some of these objects. The brightness of the name indicates the brightness of the nebula or cluster.

The brightest objects are gathered around the center of our galaxy, right on the border between Scorpius and Sagittarius, between the scorpion’s stinger and the teapot’s spout.

But for now, don’t worry about the names. Just take in the rich clouds of light as you sweep upward from Scorpius and Sagittatius (in the Northern Hemisphere) or either left or right from overhead (in the Southern Hemisphere). You don’t need to put a name to sheer beauty.

Image courtesy of Starry Night Software

This article originally published at Space.com
here

Read more: http://mashable.com/2012/07/05/milky-way-galaxy-best-in-july/

Celestial Scorpion Reigns in Night Sky

Scorpius

There’s a giant scorpion hovering overhead, but have no fear. This creepy crawler is actually the constellation Scorpius — all sparkle and no sting.

In his book The Stars in Our Heaven — Myths and Fables (Pantheon Books, 1948), author Peter Lum writes:

The scorpion is essentially a creature of darkness, a furtive little animal that lurks in the shadows, hides under stones or in any dark crevice and cannot bear to face the light … only at night does it come out in search of its prey. Although seldom fatal (its sting) is extremely painful; hence the scorpion is usually disliked, feared and avoided by anyone who has ever come in contact with him.

But so far as stargazing is concerned, it’s a whole different story, as Lum is quick to point out:

The scorpion may be an insignificant and ugly little beast, but the stars that bear its name form one of the most beautiful and conspicuous constellations in the sky. What is more remarkable is that it looks like a scorpion. At least it looks like some creature with a long and curving tail, or like a … great fish hook.

And if you face due south at around 11 p.m. local time this week, you may be able to get the best view of this magnificent star pattern — the constellation Scorpius — which ironically represents a lowly, creepy-crawly thing that has few friends.

Scorpius is a constellation that can be best appreciated by southerners. Those who live in the far-northern United States, southern Canada or the British Isles will have part or even all of its tail hidden below the southern horizon. As one progresses farther south, the Scorpion slowly climbs the southern sky.  For those who live in Australia, New Zealand, South Africa, northern Argentina, Uruguay, most of Brazil, northern Chile and southern Peru Scorpius lies directly overhead. The Milky Way Galaxy passes through the lower extremities of the Scorpion.  Here, clouds of stars and dark interstellar dust combine in a bewildering array as seen in binoculars and amateur telescopes.

The Scorpion’s brightest star is the first-magnitude Antares, displaying a reddish hue. To the ancients, this distinctive red color suggested the planet Mars, and the name Antares means literally “The Rival of Ares” — Ares being the Greek name for the God of War. I’ve always felt that even on those occasions when Mars outshines Antares, it still rivals Mars in terms of its fiery color. The so-called Red Planet actually glows with an orange-yellow luster, whereas the star Antares always glows with ruddy hue. In the time of Confucius, Chinese astronomers called this star Ta Who, “The Great Fire.”

Antares is a cool, red supergiant star, about 604 light-years away. It is 9,000 times more luminous and about 700 times the diameter of our sun. If our solar system were centered on Antares, the orbit of the Earth would easily fit inside the star. Put another way, if we could reduce our sun down to the size of a baseball, Antares would be a globe measuring more than 134 feet (nearly 41 meters) in diameter.

Yet, despite these impressive statistics, it should be noted that the overall density of Antares is less than one-millionth that of the sun. Antares is also relatively cool as stars go, only about 6,500 degrees Fahrenheit (3,593 degrees Celsius) compared to 11,000 degrees Fahrenheit (6,093 degrees Celsius) for the sun. The star’s low temperature accounts for its ruddy color.

Antares also has a small, very hot companion, bluish-white in color, but yet has been described appearing as “… a little spark of glittering emerald” because of its proximity and contrast to ruddy Antares. The two stars orbit each other over a span of nearly 900 years, separated by a distance of about 500 times Earth’s distance from the sun.

Of all the constellations, only Orion can boast more bright stars than Scorpius. And indeed, there were mythological reasons for the scorpion’s placement in our summer sky. The most famous legend has Scorpius representing the creature that stung Orion, the Mighty Hunter to death. To honor Orion, the Scorpion was placed opposite him in the sky, so that these celestial antagonists will never meet again. And supposedly that’s why when Orion is disappearing below the western horizon during spring evenings, the Scorpion is beginning to poke his head up in the southeast.

Image courtesy of Luis Argerich/Flickr

Editor’s note: If you snap an amazing photo of the night sky and you’d like to share it for a possible story or image gallery on SPACE.com, please send images and comments, including equipment used, to managing editor Tariq Malik at spacephotos@space.com.

Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmer’s Almanac and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y. Follow us on TwitterFacebook and Google+. Original article on SPACE.com.

This article originally published at Space.com
here

Read more: http://mashable.com/2013/06/28/weekend-stargazing-celestial-scorpion-reigns-in-night-sky/

Notion Of Alien Megastructure Blocking Light From Distant Star Bites The Dust

The star KIC 8462852 rose to fame this year when astronomers discovered that its light occasionally dimmed in a really weird way. At the time, no one explanation could describe the stars odd light curve. Several possibilities for causing this were proposed even including the potential of an alien megastructure around the star, blocking the light.

With our latest observations of the star, submitted to the Monthly Notices of the Royal Astronomical Society, we show that the most promising explanation is that the starlight is being obscured by the remnants of a family of smashed-up comets. A cloud of dusty debris, circling the star on an eccentric orbit, would block out some of the light when it crosses our line of sight. This scenario is now supported by many astronomers.

Id be delighted if the Kepler space telescope has discovered a civilisation in our galaxy that has built a gigantic artificial structure such as a Dyson Sphere to harvest the energy of their sun. In fact, Im sure that advanced space-faring societies do exist in the Milky Way. However, part of being a good scientist is to be a good sceptic. To infer the presence of an alien megastructure requires a lot of assumptions.

The importance of dust

One of the key things we need to know about the KIC 8462852 system is the amount of emission at long wavelengths of light particularly the sub-millimetre and millimetre part of the electromagnetic spectrum. This light would be a signature of dust around the star, glowing when heated by starlight.

In astronomical terms, dust refers to particles or small grains composed mainly of carbon and silicon. This material is formed within stars and dispersed into interstellar space when they die. Along with other heavy elements it forms the basis of new solar systems. We owe the existence of Earth to such material.

To carry out the analysis we used data from the Submillimeter Array and the James Clerk Maxwell Telescope. We did not detect any millimetre or sub-millimetre emission at all around the star. This does not mean that there is no dust, but it allows us to place sensitive upper limits on how much dust is present.

Star KIC 8462852 seen in infrared and ultraviolet respectively. NASA

In the inner solar system, within a radius of about 2-8 AU (1 AU is the average Sun-Earth distance), we estimated that there must be less dust than a few millionths of the Earths mass. This helped us eliminate one theory about whats causing the dimming: a huge cloud of debris from the collision of two or more planets that is now orbiting the star theres simply not enough dust present to support that idea.

However, analysis of the light curve suggested that just a billionth of an Earth-mass of dust could explain the dimming, provided that the dust is on the correct orbit around the star. This rather small amount of dust was not ruled out by our observations, and we estimated that the complete disintegration of the equivalent of about 30 Halleys Comets on highly elliptical orbits between 0.1 and 26 AU could explain the dimming of the starlight. At the moment, this is the best bet to explain KIC 8462852s weird light curve, and is supported by other data too.

Can we rule out aliens?

A Dyson-like structure would be expected to glow infrared at shorter wavelengths than the long wavelengths we observed. This is because its temperature would be fairly hot in comparison to the temperature of the dust. In fact, no Dyson-like infrared signature from KIC 8462852 has been detected in other data.

Also, assuming some sort of radiation-harvesting megastructure was located in the inner solar system, the construction process would presumably generate a fair amount of dusty debris, since it would require extensive mining of a large number of asteroids and small planets. Considering the very low mass of dust present within 8 AU of the star constrained by our observations, it seems unlikely. So, if a megastructure does exist around this star, the civilisation that made it is incredibly tidy.

Serendipity

Oh, and theres something else. As often happens in science, our measurements may have accidentally led us to another discovery. The observation happened to cover another star, called TYC 3162-977-1. Straddling its position are two bright sources of sub-millimetre light that we believe might be a dusty debris disc a flattened, rotating, dusty environment around a star from which planets form.

The cross marks the position of the star TYC 3162-977-1. The two blobs straddling it are bright sub-millimetre detections that could be the signature of the largest debris disc ever found. Thompson et al. (2015)

We calculated that the chance of finding such an alignment by chance is less than 0.6%. We know of lots of debris discs, but what makes this one interesting is its size. The distance to the star is something between 200 and 650 light years. This means that the size of this debris disc is something like 1000 AU. This would make it the largest such disc ever discovered watch this space.

James Geach, Royal Society University Research Fellow, University of Hertfordshire

Read more: http://www.iflscience.com/space/notion-alien-megastructure-blocking-light-distant-star-bites-dust

Unbelievable Facts About Our Universe

Exoplanet covered in burning ice

Gliese 436 b is a Neptune-sized exoplanet located about 33 light-years away in the constellation Leo. Astronomers believe that it embodies exotic states of water that causes its surface to be covered in burning ice. The pressure on the planet forces the ice to stay solid, but the extreme surface temperature of 570° F (300° C) superheats the water, causing it to come off as steam. 

Eau de Cosmos

Though it is impossible to smell space directly or through a spacesuit, astronauts report that upon returning from a spacewalk, their gear smells distinctively like seared steak, hot metal, and arc welding fumes. The source of this odor could be byproduct from dying stars, the traces of which can be found throughout the universe. 

Image credit: Jerry Attrick

 

Intergalactic kegger

About 10,000 light-years away in the constellation Aquila, there is a cloud of alcohol with a diameter 1,000 times larger than our solar system. The amount of ethyl alcohol present in the cloud could serve up to 400 septillion (400, followed by 24 additional zeros) drinks. 

Closest neighbor

The Andromeda galaxy is our closest galactic neighbor, roughly 2.5 million light-years away. Though it is 140,000 light-years across, it isn’t bright enough to be seen in the night sky by our eyes. If it were brighter, it would appear six times larger than the full moon. 

Composite image credit: Tom Buckley-Houston, original (sans Andromeda) credit: Stephen Rahn

Earth under pressure

Black holes are formed when some very large stars collapse and condense all of their mass into a very small area, known as the Schwarzschild radius. Earth’s Schwarzschild radius is just below nine mm (1/3 inch), and if it were to be compressed below that size, our planet would become a black hole. For a person to become a black hole, they would have to be compressed smaller than a proton.

Stellar nursery

Though the birth and death of stars don’t happen instantaneously, the process happens fairly frequently. By using observed star formation and supernova events within the Milky Way, astronomers have estimated that 275 million stars are born and die throughout the observable universe each day. This totals more than 100 billion over the course of a year.

Image credit: NASA, ESA, and the Hubble SM4 ERO Team

 

Galactic year

It takes 24 hours for Earth to rotate on its axis to make a day, and 365 days to orbit around the sun for a year. It takes around 230 million years for our solar system to complete a single orbit around the Milky Way. The last time it was in its current position, the earliest dinosaurs had just appeared, and flowering plants wouldn’t evolve for another 100 million years.

Macerated Milky Way

Our solar system may smell like hot metal and seared steak, but what about the middle of the Milky Way? According to recent research from the Max Plank Institute, it smells like raspberries and tastes like rum. They found that ethyl formate, a key chemical component for both raspberries and rum, can be readily found at the center of our galaxy. Can’t choose between raspberries or rum? Why not just soak the berries in the rum and call it a party?

Image credit: Pukey Cow

Time flies

If you have ever wished there were more hours in the day, just be patient. Every century, Earth’s rotation slows down by about 1.4 milliseconds. When the dinosaurs were around, a day lasted about 23 hours. NASA reports that Earth’s rotation was exactly 24 hours in 1820, but is now off by 2.5 milliseconds.

Habitable zones

There are anywhere between 200-400 billion stars in the Milky Way and an estimated 100 billion planets. Around one in five stars are like our sun, and astronomers have estimated that about 22% of them have planets the size of Earth in their habitable zone, where water can exist as a liquid. This means there could be 8.8 billion planets within the galaxy capable of supporting life (not accounting for composition of the planet or its atmosphere).

Image credit: NASA Ames/SETI Institute/JPL-Caltech

White noise

When analog television sets aren’t tuned to a channel correctly, it results in static and white noise. Around 1% of that is radiation left over from the Big Bang, better known as the Cosmic Microwave Background (CMB). This interference between overlapping signals actually allowed Arno Penzias and Robert Wilson to discover the CMB in 1965.

Quasar query

Quasars occur when gas swirls around a black hole very quickly, and friction causes it to heat up, emitting light. Astronomers have a discovered a group of 73 quasars that are over 6.5 times larger than the average quasar group. This structure is over four billion light-years wide, and actually cannot be explained by the Theory of General Relativity. Theoretically, it shouldn’t even exist.

Image credit: ESO/M. Kornmesser

Spin cycle

Pulsars are magnetized neutron stars that spin incredibly fast and blast out a beam of radiation, kind of like a lighthouse beacon. The fastest known pulsar is PSR J1748-2446ad, located around 18,000 light-years away in the constellation Sagittarius. Though it is of average size for a neutron star, it spins an astonishing 716 times per second. This is nearly a quarter of the speed of light, and exceeds what theories say is possible.

Read more: http://www.iflscience.com/space/space-oddities-unbelievable-facts-about-our-universe

Papyrus Reveals Ancient Egyptian Astronomical Knowledge

Researchers from the University of Helsinki have proposed that ancient Egyptians 3,000 years ago were the first to record the variability of a distant star and their records could provide useful information for astronomers today.

A new paper published in PLOS ONE explains how the Egyptian Cairo Calendar from 1244 to 1163 B.C. describes the variability of a binary star system called Algol. In the calendar, there are two significant periods of time for two gods 29.6 and 2.85 days. The former relates to the period of the Moon, while the latter almost perfectly matches the variability of Algol which today is 2.867 days, or two days, 20 hours, and 49 minutes.

This theory had been proposed in 2013 but, understandably, had been met with some skepticism. However, the researchers now say they are more confident in their claims, and say that Algol relates to the deity Horus.

I would have serious doubts, if someone claimed, for example, that the Bible contains information about water in Mars, said lead author Lauri Jetsu in a statement. We claimed that Ancient Egyptian religious texts contain astrophysical information about Algol. It was no surprise to us that there were, and there still are, sceptics.

Shown is an extract of the Cairo Calendar papyrus, used courtesy of Lauri Jetsu

An eclipsing binary is a pair of stars that, as viewed from Earth, rotate around each other and block each other’s light. Thus, this particular star dims regularly in brightness as it orbits its companion. Algol is found in the constellation Perseus about 92.8 light-years from us; the larger star is about 3.5 times the radius of the Sun, and the smaller about 2.7. They are separated by about 0.062 astronomical units (AU, one AU is the Earth-Sun distance).

The variability of Algol, which can be seen with the naked eye, was thought to have been first recorded by Italian astronomer Geminiano Montanari in 1667, although it was not until 1783 that British astronomer John Goodricke suggested another object may be the cause of the dimming. Based on this latest assumption, however, the record for discovery of this star’s variability may have to be re-awarded.

Perhaps most interestingly, the discovery reveals that the variability of the star has decreased very slightly over three millennia, by about 0.017 days. Rather than being an error, the researchers postulate that this could be due to the transfer of mass between the two stars affecting their orbits.

In fact, this would be the first observation that confirms the period increase of Algol and it also gives an estimate of the mass transfer rate, added Jetsu, possibly providing an important tool for astronomers today to learn more about eclipsing binaries.

Read more: http://www.iflscience.com/space/ancient-egyptians-knew-about-distant-flashing-star-3000-years-earlier-thought

Mark Your Calendar for Spring Meteor Showers and Eclipses

Lunar-eclipse

As the Moon passed almost directly through the center of Earth’s shadow on July 16th, sky gazers in the Pacific hemisphere were graced by a lingering lunar eclipse.

From eclipses and planets to meteor showers galore, the northern spring season of 2014 will bring a number of eye-catching celestial sights for stargazers on Earth.

Weather permitting, some of the best spring night sky events could be readily visible without the aid of binoculars or a telescope, even from brightly-lit cities. But you’ll need to know when and where to look to make the most of the season.

I’ve always felt that many astronomers started their careers as perceptive children who responded to the thrill of witnessing a noteworthy astronomical event. So whether you want to impress a youngster, or you’re simply hoping to witness a head-turning astronomical event for yourself, it always helps to be ready in advance by marking your calendar and highlighting a number of these special dates:

April 14 and 15: Mars’ closest approach in 2014 and a total eclipse of the moon

During the overnight hours of April 14 and 15, it will be a night for viewing first Mars and later the full moon.

First, Mars will come to within 57.4 million miles of our planet, making its closest approach to us since Jan. 3, 2008. All through the night, Mars will resemble a dazzling star shining with a steady fiery-colored tint making it a formidable sight; its brightness will match Sirius, the brightest of all the stars.

As a bonus, later that very same night (actually during the early hours of April 15) North America will have a ringside seat to see a total lunar eclipse when the Full Moon becomes transformed into a mottled reddish ball for 78 minutes as it becomes completely immersed in the shadow of the Earth.

This total lunar eclipse will be the first one widely visible from North America in nearly 3.5 years. The Americas will have the best view of this eclipse, although over the Canadian Maritimes, moonset will intervene near the end of totality. Of special interest is the fact that the moon will appear quite near to the bright star Spica, in the constellation Virgo, during the eclipse. They actually will be in conjunction a couple of hours prior to the onset of totality, but they’re still relatively near to each other when the eclipse gets underway.

April 22: The Lyrid meteor shower

Rather favorable circumstances are expected for this year’s Lyrid meteor shower, predicted to be at maximum this morning. The radiant, located near the brilliant bluish-white star Vega, rises in the northeast about the time evening twilight ends, and viewing will improve until light from the last-quarter moon begins to interfere just after 2 a.m. your local time.

Under the best conditions, 10 to 15 members of this shower can be seen in an hour by a single observer. The Lyrids remain about a quarter of their peak number for about two days. These bright meteors are associated with Thatcher’s Comet of 1861.

April 28 and 29: A Ring Eclipse that nobody will see?

It is quite possible that only penguins will witness the annular solar eclipse, also known as a “ring of fire” solar eclipse. That’s because it will occur within the uninhabited region of Wilkes Land in Antarctica.

Those living in southernmost parts of Indonesia as well as Australia (where it will be autumn) will at least get a view of a partial eclipse of the sun. Because the axis of the moon’s antumbral shadow misses the Earth and only its edge grazes Antarctica, it makes an accurate prediction of the duration of annularity all but impossible.

May 6: The Eta Aquarid meteor shower

The annual Eta Aquarid meteor shower — “shooting stars” spawned by the famed Halley’s Comet — is scheduled to reach maximum early this morning. It’s usually the year’s richest meteor display for Southern Hemisphere observers, but north of the equator the Eta Aquarid shower is one of the more difficult annual displays to observe.

From mid-northern latitudes, the radiant (from where the meteors appear to emanate) rises about 1:30 a.m. local daylight time, scarcely two hours before morning twilight begins to interfere. At peak activity, about a dozen shower members can be seen per hour by a single observer with good sky conditions from latitude 26 degrees North, but practically zero north of latitude 40 degrees. The shower remains active at roughly one-half peak strength for a couple of days before and after the maximum. Conditions this year are excellent; the moon is absent from the predawn sky for more than a week around maximum.

May 10: Saturn at opposition

The ringed planet Saturn reaches opposition; it rises in the east-southeast at dusk, is due south in the middle of the night and sets in the west-southwest at dawn. Once it gains enough altitude, it appears similarly as bright as the zero-magnitude stars Arcturus and Vega.

Saturn’s famous rings appear much more impressive than in recent years, since they are now tipped by 21.5 degrees from edge on.

May 24: Possible outburst of bright meteors

Perhaps the most dramatic sky event in 2014 could come at the start of the Memorial Day weekend. In the predawn hours of Saturday, May 24, our planet is expected to sweep through a great number of dusty trails left behind in space by the small comet P/209 LINEAR.

This unusual cosmic interaction might possibly result in an amazing, albeit brief display of meteors — popularly known as “shooting stars” — perhaps numbering in the many dozens . . . or even hundreds per hour. Nobody knows exactly how many meteors will be seen, but several meteor scientists believe that because the particles will be unusually large, the meteors will be outstandingly bright.

May 25: Mercury attains its greatest elongation

The planet Mercury will reach its greatest elongation, or greatest angular distance, east of the sun on this night. This is Mercury’s best evening apparition of the year; it sets about 100 minutes after sunset. An hour after sunset, look low above the west-northwest horizon; the speedy planet should be easily visible as a yellowish “star.”

Mercury will appear somewhat brighter up to two weeks before this date, and noticeably dimmer for about a week afterwards.

This article originally published at Space.com
here

Read more: http://mashable.com/2014/04/01/spring-stargazing-guide/

See ‘Summer Triangle’ in Night Sky This Weekend

Summer-triangle

This weekend, during the late evening hours, search for the famous “Summer Triangle” high in the eastern sky.

The triangle consists of three of the brightest stars in the sky, each the brightest in its own constellation. Bluish-white star Vega in Lyra (the lyre) is the brightest in the triangle, with yellow-white Altair in Aquila (the eagle) and white Deneb in Cygnus (the swan), following it as second- and third-brightest in the configuration.

From our viewpoint, Vega appears twice as bright as Altair and more than three times brighter than Deneb. But sometimes things are not always what they seem. We know that Vega clearly is more luminous compared to Altair, because it’s situated at a greater distance from us.  Altair is 17 light years away, while Vega is just a little farther out at 25 light years away.

The light you’re seeing from Altair tonight started on its journey to Earth in 1996, and the light from Vega started on its way toward Earth back in 1988. But brilliant Vega actually pales in comparison with Deneb, one of the greatest supergiant stars known.

Deneb’s distance measures 1,467 light-years from Earth with a luminosity computed to be more than 60,000 times that of the sun. Because its light takes nearly 15 centuries to reach us, Deneb merely appears as a fairly conspicuous but by no means particularly notable star.

See the Milky Way

With the moon arriving at new phase on Monday, July 8, and then waxing to just a thin crescent phase by week’s end, there is no better time than now to observe the beautiful summer Milky Way.

Under a dark sky with a good pair of binoculars or a telescope you can now observe millions of sparkling little stars that make up this glowing, irregular belt of luminosity.

It appears to arch from the north-northeast to the south-southeast, with its brightest and most spectacular region running across the summer triangle and beyond toward the south-southeast horizon.

There appears to be a great black rift dividing it into two streams (called the “dark bifurcation”), beginning with Cygnus and extending down toward the south. Also in Cygnus is the black void known as the “northern coal stack.” The coal stack and the rift are not holes in the Milky Way, but rather are vast clouds of dust “floating” out in interstellar space which present a solid and impenetrable curtain between us and the more distant stars.

Star-Crossed Lovers

There have been many stories, myths and legends told about the Milky Way across different cultures.

In a Japanese legend involving the galaxy, the star Vega represented Orihime, the weaving princess, who produced brilliantly colored fabrics. Across the “heavenly river” (the Milky Way), Altair represented the cow herder Hikoboshi, who was also known as Kengyu.

After meeting each other, they received divine permission to marry, whereupon both abandoned their occupations. This angered the gods who consequently separate them and send them back to their original jobs on opposite sides of the heavenly river.

The couple, however, received permission from the gods to get together for one night each year. That special night is July 7 — but only if the sky is clear.

As a result, the evening of July 7 has evolved into a young people’s holiday in Japan called Tanabata, meaning “evening of the seventh.” Prayers are offered for clear skies so that Orihime and Hikoboshi, the star-crossed lovers can be reunited.

Popular customs relating to the festival vary by region, but generally, girls wish for better sewing and craftsmanship, and boys wish for better handwriting by writing wishes on strips of paper. The date of Tanabata also varies by region, but the first festivities begin on July 7 of the Gregorian calendar.

The original Tanabata date was based on the Japanese lunisolar calendar, which is about a month behind the Gregorian calendar. As a result, some festivals are held on July 7, some last for a few days around August 7 and others take place on the seventh day of the seventh lunar month of the traditional Japanese lunisolar calendar, which is usually in August in the Gregorian calendar.

This year, the Gregorian date of “the seventh day of the seventh lunar month of the Japanese lunisolar calendar” will fall on Aug. 13.

Editor’s note: If you snap an amazing picture of the night sky that you’d like to share for a possible story or image gallery send photos, comments and your name and location to Managing Editor Tariq Malik at spacephotos@space.com.

Image courtesy of Flickr, Socalastro

This article originally published at Space.com
here

Read more: http://mashable.com/2013/07/05/summer-triangle/

Our Nearest Galactic Neighbor Revealed In Stunning Clarity

This stunning new image from the European Southern Observatory (ESO) reveals the closest galaxy to our Milky Way in exquisite detail.

Called IC 1613, it is more accurately a dwarf galaxy,owing to its relatively minute size. Also known as Caldwell 51, this galaxy measures roughly 10,000 light-years across, compared to 100,000 light-years for the Milky Way. It is located about 2.3 million light-years from Earth in the constellation Cetus.

This latest image reveals just how clean the galaxy is, with very little cosmic dust, meaning its innards can be studied in great detail. It was taken by the OmegaCAM camera on the ESOs Very Large Telescope (VLT) Survey Telescope in Chile, and also reveals a cloud of bright pink gas within the galaxy.

Discovered in 1906 by German astronomer Max Wolf, we now know that IC 1613 is part of our Local Group,a neighborhood of more than 50 galaxies. And we know IC 1613s distance from us very precisely, thanks to its cleanliness. This allows us to see distance marker stars, Cepheid variables and RR Lyrae variables, which flash with a regular beat that lets us calculate their distance.

In fact, IC 1613 helped astronomers refine the technique of using these stars to measure distances in the universe, something first proposed by the underappreciated astronomer Henrietta Swan Levitt in the early 20th Century.

Read more: http://www.iflscience.com/space/our-nearest-galactic-neighbour-revealed-stunning-clarity

Astronomers Have Discovered The Oldest Stars In Our Galaxy

An international team of astronomers has discovered some of the oldest stars in the Milky Way.In the process, they were able to learna lot about the abundance of different elements in the very early universe.

These stars, which are part of the second generation of stars to form in the universe, were discovered near the very center of the Milky Way and they are believed to have started shining200 million years after the Big Bang. The scientists thinkthat their findings, published in Nature,give an indication ofthe life and death of the very first stars.

The first stars are believed to have been huge, havingup to 1,000 times the mass of the Sun. It is thought that when these objects reached the end of their lives, they exploded inhypernova explosions,tens of times stronger than the supernovae we see in the universe today.The first generation havenot been directly observed yet, but astronomers hope to see them when the James Webb Space Telescope(JWST) starts operation in 2018.

The second generation, including the stars from this study, are metal-poor: They are made almost exclusively of helium and hydrogen, with only traces of heavier elements (the metals). The more metal a star has, the quicker it forms and the smaller it is.

After the Big Bang, the universe was composed of just hydrogen and helium. This is why the first-generation stars were so big.The carbon in our bodies, the oxygen in the air and all the other heavy elements we find in the universe were formed by the first two generations of stars.

The discovery didnt come easy. There are millions of stars in the Milky Ways bulge, so the team had to develop a strategy to make the gargantuan task of observing them in detailmore manageable.

Since very metal-poor stars are slightly bluer than other stars, the researchersselected 14,000 promising stars from the ANU SkyMapper telescope in Australia. Only 23 of themwerethen studied inmore detail in follow-up observations.

There are so many stars in the centerof our galaxy finding these rare stars is really like looking for a needle in a haystack, said co-authorDrAndrew Casey of Cambridges Institute of Astronomy in a statement. But if we select these stars in the right way, its like burning down the farm and sweeping up the needles with a magnet.

The elements released by the first stars act as a chemical signature that is still present in the stars observed in the study.

This work confirms that there are ancient stars in the centre of our galaxy. The chemical signature imprinted on those stars tells us about an epoch in the universe thats otherwise completely inaccessible, said Casey. The universe was probably very different early on, but to know by how much, weve really just got to find more of these stars: more needles in bigger haystacks.

Read more: http://www.iflscience.com/space/discovery-ancient-stars-sheds-light-primordial-hypernovae

The Pulsar That ‘Vaporized’ a Billion-Ton Asteroid

Pulsar-in-space

This artist’s concept depicts the pulsar planet system discovered by Aleksander Wolszczan in 1992.
Image: NASA JPL-Caltech

You know when you’re having a bad day when you get hit by a billion ton asteroid. But for a pulsar 37,000 light-years away, it’s just a another day at the office. And besides, PSR J0738-4042 has an uber-powerful X-ray blaster to deal with errant space rocks.

Astronomers of Australia’s Commonwealth Scientific and Industrial Research Organisation made the pulsar-pounding, asteroid-zapping discovery while using the Parkes Telescope to study the dusty, high-radiation environment surrounding the tiny spinning husk of the dead star. Pulsars are spinning compact stellar objects known as neutron stars that generate powerful beams of radiation from their intensely magnetized poles that, if aligned correctly with Earth, can be observed as ultra-precise radio pulses.

Pulsars are considered the most precise ‘clocks’ in the universe, but if a pulsar’s pulse timings abruptly change, a cataclysmic event has likely occurred.

In the case of PSR J0738-4042, the CSIRO astronomers noticed weird changes in the pulsar’s timing and its characteristic pulse, signals that the researchers have attributed to multiple asteroid hits.

“One of these rocks seems to have had a mass of about a billion tons,” said CSIRO astronomer Ryan Shannon in a press release.

In 2008, Shannon theorized that should a large rocky object, like an asteroid or even a small planet, collide with a pulsar, the pulsar will react in a very precise way; now it seems PSR J0738-4042 has become the prime candidate as observational evidence for this theory. The time of the pulse has lengthened and the radio signal received by Parkes has changed.

“We think the pulsar’s radio beam zaps the asteroid, vaporizing it. But the vaporized particles are electrically charged and they slightly alter the process that creates the pulsar’s beam,” said Shannon. The electrically charged particles interact with the pulsar’s magnetic field, like a magnetic blender, generation energy, sapping some of the pulsar’s angular momentum. This has a drag effect, slowing the spin rate. However, once all the ionized material has been converted to energy, the pulsar is expected to return to its pre-asteroid strike spin rate.

It is thought that the surrounding asteroids originated from the star that exploded to form the pulsar. The pulsar is a byproduct of a supernova, but before the star went supernova, it formed a system of rocky bodies, such as the billion ton asteroid and, possibly, planets.

This asteroid-vaporizing event is exiting in that it proves that rocky debris that formed before the star went supernova persisted after the star’s death, forming a debris disk around PSR J0738-4042. It’s possible that the surviving debris disk could be rejuvenated, spawning the agglomeration of larger and larger objects, potentially forming new planets.

The discovery of asteroid vaporization events close to PSR J0738-4042 is an interesting development in the study of disks surrounding pulsars. For example, another pulsar, J0146+61, has been found to be sporting a dusty debris disk and, in 1992, two planet-sized objects were discovered orbiting pulsar PSR 1257+12.

“This sort of dust disk could provide the ‘seeds’ that grow into larger asteroids,” said Ph.D. student Paul Brook, of the University of Oxford and CSIRO who led the PSR J0738-4042 study.

This research has been published in The Astrophysical Journal Letters.

This article originally published at Discovery News
here

Read more: http://mashable.com/2014/02/23/pulsar-zaps-giant-asteroid/