milky way Archives

June 13, 2016April 8, 2018 by Nancy Atkinson

Gorgeous Photos of Earth and the Night Sky: TWAN Photo Contest Winners Announced

'Northern Lights above Lofoten,' a photo taken by Alex Conu, won first prize in the 'Against the Lights' category in the 2016 International Earth & Sky Photo Contest. The image was taken from a mountaintop in Lofoten Islands, Norway. Credit and copyright: Alex Conu.

The winners of the 7th annual Earth & Sky Photo Contest have been announced, and wow, these images are absolutely stunning! The contest really highlights the beauty of the night sky, and its mission is to spread the message to cut down on light pollution while helping to preserve the last remaining natural night environments and night skies in the world. The contest was organized by The World at Night (TWAN) and other sister organizations.

“The sky above us is an essential part of our nature, a heritage for us and other species on this planet,” said TWAN founder and contest chair, Babak Tafreshi.”The contest main goal is to present the night sky in this broader context that helps preserving the natural night sky by reconnect it with our modern life.”

See more winning photos below:

The second place winner in the ‘Against the Light’ category is Carlo Zanandrea from Italy for "All that Glitters is not Gold" taken in December 2015 showing constellation Orion rising over lights and fog in the province of Treviso in northeastern Italy. Credit and copyright: Carlo Zanandrea. — The second place winner in the ‘Against the Light’ category is Carlo Zanandrea from Italy for “All that Glitters is not Gold” taken in December 2015 showing constellation Orion rising over lights and fog in the province of Treviso in northeastern Italy. Credit and copyright: Carlo Zanandrea.

Just last week, a group of Italian and American scientists unveiled a new global atlas of light pollution, and sadly, they said the results show the Milky Way is “but a faded memory to one-third of humanity and 80 percent of Americans.”

“We’ve got whole generations of people in the United States who have never seen the Milky Way,” said Chris Elvidge, a scientist with NOAA’s National Centers for Environmental Information. “It’s a big part of our connection to the cosmos — and it’s been lost.”

These photos from Earth & Sky Contest really display that important connection, with people and places on Earth being a big part of many of the images – the classic definition of “TWAN-style” photography. According to the contest theme of “Dark Skies Importance,” the submitted photos were judged in two categories: “Beauty of The Night Sky” and “Against the Lights.”

“The selected images are those most effective in impressing public on both how important and delicate the starry sky is as an affecting part of our nature, and also how bad the problem of light pollution has become,” TWAN said in their press release. “Today, most city skies are virtually devoid of stars. Light pollution (excessive light that scatters to the sky instead of illuminating the ground) not only is a major waste of energy, it also obscures the stars, disrupts ecosystems and has adverse health effects.”

"The Photographer" by Nicholas Roemmelt from Austria is the second place winner in the 'Beauty of the Night Sky category, taken in March 2015 in Stockiness, Iceland. Credit and copyright: Nicholas Roemmelt — “The Photographer” by Nicholas Roemmelt from Austria is the second place winner in the ‘Beauty of the Night Sky category, taken in March 2015 in Stockiness, Iceland. Credit and copyright: Nicholas Roemmelt

The winning images were chosen on their “aesthetic merit and technical excellence,” said David Malin of the judging panel, who is well-known pioneer in scientific astrophotography. “We believe they accurately reflect the state of the art in TWAN-style photography. The competition encourages photographers with imagination to push their cameras to their technical limits, and to produce eye-catching images that appear perfectly natural and are aesthetically pleasing.”

This photo, "Viking Lights" by Adam Woodworth from USA, won in the composite section of the ‘Beauty of the Night Sky’ category, where frames of various exposure or focus settings are blended. This image was captured in Newfoundland, Canada in June, 2015. Credit and copyright: Adam Woodworth. — This photo, “Viking Lights” by Adam Woodworth from USA, won in the composite section of the ‘Beauty of the Night Sky’ category, where frames of various exposure or focus settings are blended. This image was captured in Newfoundland, Canada in June, 2015. Credit and copyright: Adam Woodworth.

In the photo sequence submissions, the winner in the Beauty category is "Total Solar Eclipse from Svalbard" by Thanakrit Santikunaporn from Thailand. He captured the eclipse phases every 3 minutes over frozen landscape of Svalbard, Norway on March 20, 2015. Credit and copyright: Thanakrit Santikunaporn. — In the photo sequence submissions, the winner in the Beauty category is “Total Solar Eclipse from Svalbard” by Thanakrit Santikunaporn from Thailand. He captured the eclipse phases every 3 minutes over frozen landscape of Svalbard, Norway on March 20, 2015. Credit and copyright: Thanakrit Santikunaporn.

The contest was open to anyone of any age, anywhere in the world; to both professional and amateur/hobby photographers. It has been an annual event since 2009 (initially for the International Year of Astronomy) by TWAN, the National Optical Astronomy Observatory, and Global Astronomy Month from Astronomers Without Borders. The contest supports efforts of the International Dark Sky Association (IDA) and other organizations that seek to preserve the night sky.

The images were taken in 57 countries and territories including Algeria, Antarctica, Australia, Austria, Bahamas, Belgium, Bolivia, Brazil, Canada, China, Colombia, Croatia, Czech Republic, Egypt, England, Estonia, Finland, France, Germany, Greece, Guatemala, Guam, Hungary, Iceland, India, Indonesia, Iran, Ireland, Italy, Japan, Jordan, Kenya, Lithuania, Madagascar, Malaysia, Malta, Morocco, Norway, New Zealand, Paraguay, Peru, Philippines, Poland, Reunion (France), Romania, Russia, Scotland, Sri Lanka, South Africa, Spain, South Africa, Sri Lanka, Sweden, Switzerland, Tanzania, Thailand, Ukraine, and USA.

See all the images and more information about them at TWAN. Click on each image for larger versions. A larger version of the lead image can be found here.

You can see the global atlas of light pollution here, which was created from data from the NOAA/NASA Suomi National Polar-orbiting Partnership satellite and calibrated by thousands of ground observations.

And here’s a video that includes all the winning images:

June 7, 2016June 7, 2016 by Cory Schmitz

Metropolitan Milky Way

JanikAlheit-CPTMilkyPano — A breathtakingly rare view of the southern hemisphere Milky Way above a major city - a 42-panel panorama. Photo: Janik Alheit

This article was written by contributing author Janik Alheit, and is used by permission from the original at PhotographingSpace.com.

When it comes to my style of photography, preparation is a key element in getting the shot I want.

On this specific day, we were actually planning on only shooting the low Atlantic clouds coming into the city of Cape Town. This in itself takes a lot of preparation as we had to keep a close eye on the weather forecasts for weeks using Yr.no, and the conditions are still unpredictable at best even with the latest weather forecasting technology.

We set out with cameras and camping gear with the purpose of setting up camp high up on Table Mountain so as to get a clear view over the city. The hike is extremely challenging at night, especially with a 15kg backpack on your back! We reached our campsite at about 11pm, and then started setting up our cameras for the low clouds predicted to move into the city at about 3am the next morning. For the next 2 hours or so we scouted for the best locations and compositions, and then tried to get a few hours of sleep in before the clouds arrived.

At about 3am I was woken up by fellow photographer Brendon Wainwright. I realised that he had been up all night shooting timelapses, and getting pretty impressive astro shots even though we were in the middle of the city. I noticed that the clouds had rolled in a bit earlier than predicted and had created a thick blanket over the city, which was acting as a natural light pollution filter.

I looked up at the skies and for the first time in my life I was able to see the core of the Milky Way in the middle of the city! This is when everything changed, the mission immediately became an astrophotography mission, as these kind of conditions are extremely rare in the city.

How to Photograph the Milky Way — Learn how to shoot the Milky Way at PhotographingSpace.com!

Composition

After shooting the city and clouds for a while, I turned my focus to the Milky Way. I knew I was only going to have this one opportunity to capture an arching Milky Way over a city covered with clouds, so I had to work fast to get the perfect composition before the clouds changed or faded away.

I set my tripod on top of a large rock that gave me a bit of extra height so that I could get as much of the city lights in the shot as possible. The idea I had in my mind was to shoot a panorama from the center of the city to the Twelve Apostles Mountains in the southwest. This was a pretty large area to cover, plus the Milky Way was pretty much straight above us which meant I had to shoot a massive field of view in order to get both the city and the Milky Way.

The final hurdle was to get myself into the shot, which meant that I had to stand on a 200m high sheer cliff edge! Luckily this was only necessary for one frame in the entire panorama.

Gear and settings

I usually shoot with a Canon 70D with an 18mm f/3.5 lens and a Hahnel Triad 40Lite tripod. This particular night I forgot to bring a spare battery for my Canon and by the time I wanted to shoot this photo, my one battery had already died!

Luckily I had a backup camera with me, an Olympus OMD EM10 mirrorless camera. I had no choice but to use this camera for the shot. The lens on that camera was an Olympus M.Zuiko 14-42mm f/3.5 kit lens, which was not ideal, but I just had to make it work.

I think this photo is a testament to the fact that your gear is not nearly as important as your technique and knowledge of your surroundings and your camera.

I started off by shooting the first horizontal line of photos, in landscape orientation, to form the bottom edge of the final stitched photo. From there I ended up shooting 6 rows of 7 photos each in order to capture the whole view I wanted. This gave me 42 photos in total.

For the most part, my settings were 25 seconds, f/3.5, ISO 2000, with the ISO dropped on a few of the pictures where the city light was too bright. I shot all the photos in raw as to get as much data out of each frame as possible.

Editing

Astrophotography is all about the editing techniques.

In this scenario I had to stitch 42 photos into one photo. Normally I would just use the built-in function in Lightroom, but in this case I had to use software called PTGui Pro, which is made for stitching difficult panoramas. This software enables me to choose control points on the overlapping images in order to line up the photos perfectly.

After creating the panorama in PTGui Pro, I exported it as a TIFF file and then imported that file into Lightroom again. Keep in mind that this one file is now 3GB as it is made up of 42 RAW files!

In Lightroom I went through my normal workflow to bring out the detail in the Milky Way by boosting the highlights a bit, adding contrast, a bit of clarity, and bringing out some shadows in the landscape. The most difficult part was to clear up the distortion that was caused by the faint clouds in the sky between individual images. Unfortunately it is almost impossible to blend so many images together perfectly when you have faint clouds in the sky that form and disappear within minutes, but I think I did the best job I could to even out the bad areas.

A special event

After the final touches were made and the photo was complete, I realized that I had captured something really unique. It’s not every day that you see low clouds hanging over the city, and you almost never see the Milky Way so bright above the city, and I managed to capture both in one image!

The response to the image after posting it to my Instagram account was extremely overwhelming. I got people from all over the world wanting to purchase the image and it got shared hundreds of time across all social media.

It just shows you that planning and dedication does pay off!

July 23, 2015December 23, 2015 by David Dickinson

Astronomers Spot a Intriguing ‘5-Star’ Multiple System

An interesting multiple star discovery turned up in the ongoing hunt for exoplanetary systems.

The discovery was announced by Marcus Lohr of Open University early this month at the National Astronomy Meeting that was held at Venue Cymru in Llandudno, Wales.

The discovery involves as many as five stars in a single stellar system, orbiting in a complex configuration.

The name of the system, 1SWASP J093010.78+533859.5, is a phone number-style designation related to the SuperWASP exoplanet hunting transit survey involved with the discovery. The lengthy numerical designation denotes the system’s position in the sky in right ascension and declination in the constellation Ursa Major.

And what a bizarre system it is. The physical parameters of the group are simply amazing, though not as unique as some media outlets have led readers to believe. What is amazing is the fact that both pairs of binaries in the quadruple group are also eclipsing along our line of sight. Only five other quadruple eclipsing binary systems of this nature are known, to include BV/BW Draconis and V994 Herculis.

The very fact that the orbits of both pairs of stars are in similar inclinations will provide key insights for researchers as to just how this system formed.

The first pair in the system are contact binaries of 0.9 and 0.3 solar masses respectively in a tight embrace revolving about each other in just under six hours. Contact binaries consist of distorted stars whose photospheres are actually touching. A famous example is the eclipsing contact binary Beta Lyrae.

An animation of the orbits of the contact binary pair Beta Lyrae captured using the CHARA interferometer. Image credit: Ming Zhao et al. ApJ 684, L95

A closer analysis of the discovery revealed another pair of detached stars of 0.8 and 0.7 solar masses orbiting each other about 21 billion kilometres (140 AUs distant) from the first pair. You could plop the orbit of Pluto down between the two binary pairs, with room to spare.

But wait, there’s more. Astronomers use a technique known as spectroscopy to tease out the individual light spectra signatures of close binaries too distant to resolve individually. This method revealed the presence of a fifth star in orbit 2 billion kilometers (13.4 AUs, about 65% the average distance from Uranus to the Sun) around the detached pair.

“This is a truly exotic star system,” Lohr said in a Royal Society press release. “In principle, there’s no reason it couldn’t have planets in orbit around each of the pairs of stars.”

Indeed, ‘night’ would be a rare concept on any planet in a tight orbit around either binary pair. In order for darkness to occur, all five stellar components would have to appear near mutual conjunction, something that would only happen once every orbit for the hypothetical world.

Such a planet is a staple of science fiction, including Tatooine of Star Wars fame (which orbits a relatively boring binary pair), and the multiple star system of the Firefly series. Perhaps the best contender for a fictional quadruple star system is the 12 colonies of the re-imagined Battlestar Galactica series, which exist in a similar double-pair configuration.

How rare is this discovery, really? Multiple systems are more common than solitary stars such as our Sun by a ratio of about 2:1. In fact, it’s been suggested by rare Earth proponents that life arose here on Earth in part because we have a stable orbit around a relatively placid lone star. The solar system’s nearest stellar neighbor Alpha Centauri is a triple star system. The bright star Castor in the constellation of Gemini the Twins is a famous multiple heavyweight with six components in a similar configuration as this month’s discovery. Another familiar quadruple system to backyard observers is the ‘double-double’ Epsilon Lyrae, in which all four components can be split. Mizar and Alcor in the handle of the Big Dipper asterism is another triple-pair, six-star system. Another multiple, Gamma Velorum, may also possess as many as six stars. Nu Scorpii and AR Cassiopeiae are suspected septuple systems, each perhaps containing up to seven stars.

Fun fact: Gamma Velorum is also informally known as ‘Regor,’ a backwards anagram play on Apollo 1 astronaut ‘Roger’ Chaffee’s name. The crew secretly inserted their names into the Apollo star maps during training!

What is the record number of stars in one system? Hierarchy 3 systems such as Castor are contenders. A.A. Tokivinin’s Multiple Star Catalogue lists five components in a hierarchy 4 system in Ophiuchus named Gliese 644AB, with the potential for more.

How many stars are possible in one star system? Certainly, a hierarchy 4 type system could support up the eight stars, though to our knowledge, no example of such a multiple star system has yet been confirmed. Still, it’s a big universe out there, and the cosmos has lots of stars to play with.

A wide-field view of the constellation Ursa Major, with Theta Ursae Majoris selected (inset). image credit; Stellarium — A wide-field view of the constellation Ursa Major, with Theta Ursae Majoris selected (inset). Image credit; Stellarium

And you can see 1SWASP J093010.78+533859.5 for yourself. At 250 light years distant, the +9^th magnitude binary is about 1.5 degrees north-northwest of the star Theta Ursa Majoris, and is an tough but not impossible split with a separation of 1.88” between the two primary pairs.

Finder chart for 1SWAP J093010.78+533859.5 with a five degree Telrad foV. Image credit: Stellarium

Congrats to the team on this amazing discovery… to paraphrase Haldane, the Universe is proving to be stranger than we can imagine!

May 15, 2015December 23, 2015 by Bob King

Andromeda and Milky Way Might Collide Sooner Than We Think

Andromeda's halo is gargantuan. Extending millions of light years, if we could see in our night sky it would be 100 times the diameter of the Moon or 50 degrees across! Credit: NASA

The merger of the Milky Way and Andromeda galaxy won’t happen for another 4 billion years, but the recent discovery of a massive halo of hot gas around Andromeda may mean our galaxies are already touching. University of Notre Dame astrophysicist Nicholas Lehner led a team of scientists using the Hubble Space Telescope to identify an enormous halo of hot, ionized gas at least 2 million light years in diameter surrounding the galaxy.

The Andromeda Galaxy is the largest member of a ragtag collection of some 54 galaxies, including the Milky Way, called the Local Group. With a trillion stars — twice as many as the Milky Way — it shines 25% brighter and can easily be seen with the naked eye from suburban and rural skies.

Quasars are distant, brilliant sources of light, believed to occur when a massive black hole in the center of a galaxy feeds on gas and stars. As the black hole consumes the material, it emits intense radiation, which is then detected as a quasar. These photos, taken by Hubble, show them as brilliant "stars" in the cores of six different galaxies. Credit: NASA/ESA — Six examples of quasars photographed with the Hubble. Quasars are distant, brilliant sources of light, believed to occur when a massive black hole in the center of a galaxy feeds on gas and stars. As the black hole consumes the material, it emits intense radiation, which is then detected as a quasar. Lehner and team measured Andromeda’s halo by studying how its gas affected the light from 18 different quasars. Credit: NASA/ESA

Think about this for a moment. If the halo extends at least a million light years in our direction, our two galaxies are MUCH closer to touching that previously thought. Granted, we’re only talking halo interactions at first, but the two may be mingling molecules even now if our galaxy is similarly cocooned.

Lehner describes halos as the “gaseous atmospheres of galaxies”. Despite its enormous size, Andromeda’s nimbus is virtually invisible. To find and study the halo, the team sought out quasars, distant star-like objects that radiate tremendous amounts of energy as matter funnels into the supermassive black holes in their cores. The brightest quasar, 3C273 in Virgo, can be seen in a 6-inch telescope! Their brilliant, pinpoint nature make them perfect probes.

To detect Andromeda's halo, Lehner and team studied how the light of 18 quasars (five shown here) was absorbed by the galaxy's gas. Credit: NASA — To detect Andromeda’s halo, Lehner and team studied how the light of 18 quasars (five shown here) was absorbed by the galaxy’s gas. Credit: NASA

“As the light from the quasars travels toward Hubble, the halo’s gas will absorb some of that light and make the quasar appear a little darker in just a very small wavelength range,” said J. Christopher Howk , associate professor of physics at Notre Dame and co-investigator. “By measuring the dip in brightness, we can tell how much halo gas from M31 there is between us and that quasar.”

Astronomers have observed halos around 44 other galaxies but never one as massive as Andromeda where so many quasars are available to clearly define its extent. The previous 44 were all extremely distant galaxies, with only a single quasar or data point to determine halo size and structure.

Andromeda’s close and huge with lots of quasars peppering its periphery. The team drew from about five years’ worth of observations of archived Hubble data to find many of the 18 objects needed for a good sample.

This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. In this image, representing Earth's night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. (Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger) — This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. In this image, representing Earth’s night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger

The halo is estimated to contain half the mass of the stars in the Andromeda galaxy itself, in the form of a hot, diffuse gas. Simulations suggest that it formed at the same time as the rest of the galaxy. Although mostly composed of ionized hydrogen — naked protons and electrons — Andromeda’s aura is also rich in heavier elements, probably supplied by supernovae. They erupt within the visible galaxy and violently blow good stuff like iron, silicon, oxygen and other familiar elements far into space. Over Andromeda’s lifetime, nearly half of all the heavy elements made by its stars have been expelled far beyond the galaxy’s 200,000-light-year-diameter stellar disk.

You might wonder if galactic halos might account for some or much of the still-mysterious dark matter. Probably not. While dark matter still makes up the bulk of the solid material in the universe, astronomers have been trying to account for the lack of visible matter in galaxies as well. Halos now seem a likely contributor.

The next clear night you look up to spy Andromeda, know this: It’s closer than you think!

For more on the topic, here are links to Lehner’s paper in the Astrophysical Journal and the Hubble release.

March 21, 2015December 23, 2015 by Bob King

Nova in Sagittarius Brighter Than Ever – Catch it with the Naked Eye!

Nova Sagittarii 2015 No. 2 photographed this morning when it was easily visible to the naked eye at magnitude +4.4. The nova has been on the upswing since its discovered less than a week ago. Credit: Bob King

Great news about that new nova in Sagittarius. It’s still climbing in brightness and now ranks as the brightest nova seen from mid-northern latitudes in nearly two years. Even from the northern states, where Sagittarius hangs low in the sky before dawn, the “new star” was easy to spy this morning at magnitude +4.4.

While not as rare as hen’s teeth, novae aren’t common and those visible without optical aid even less so. The last naked eye nova seen from outside the tropics was V339 Del (Nova Delphini), which peaked at +4.3 in August 2013. The new kid on the block could soon outshine it if this happy trend continues.

This view shows the sky facing south-southeast just before the start of dawn in mid-March from the central U.S. The nova's located squarely in the Teapot constellation. Source: Stellarium — This view shows the sky facing south-southeast shortly before the start of dawn in late March from the central U.S. The nova is centrally located within the Teapot. Source: Stellarium

Now bearing the official title of Nova Sagittarii 2015 No. 2, the nova was discovered on March 15 by amateur astronomer and nova hunter John Seach of Chatsworth Island, NSW, Australia. At the time it glowed at the naked eye limit of magnitude +6. Until this morning I wasn’t able to see it with the naked eye, but from a dark sky site, it’s there for the picking. So long as you know exactly where to look.

The chart and photo above will help guide you there. At the moment, the star’s about 15° high at dawn’s start, but it rises a little higher and becomes easier to see with each passing day. Find your sunrise time HERE and then subtract an hour and 45 minutes. That will bring you to the beginning of astronomical twilight, an ideal time to catch the nova at its highest in a dark sky.

Use this AAVSO chart to pinpoint the nova's location and also to help you estimate its brightness. Numbers shown are star magnitudes with the decimal points omitted. Credit: AAVSO — Use this AAVSO chart to pinpoint the nova’s location and also to help you estimate its brightness. Numbers shown are star magnitudes with the decimal points omitted. Credit: AAVSO

To see it with the naked eye, identify the star with binoculars first and then aim your gaze there. I hope you’ll be as pleasantly surprised as I was to see it. To check on the nova’s ups and downs, drop by the American Association Variable Star Observers (AAVSO) list of recent observations.

Seeing the nova without optical aid took me back to the time before the telescope when a “new star” in the sky would have been met with great concern. Changes in the heavens in that pre-telescopic era were generally considered bad omens. They were also thought to occur either in Earth’s atmosphere or within the Solar System. The universe has grown by countless light years since then. Nowadays we sweat the small stuff – unseen asteroids – which were unknown in that time.

AAVSO light curve showing the nova's brightening trend since discovery. Dates are at bottom, magnitudes at left. Credit: AAVSO — AAVSO light curve showing the nova’s brightening since discovery. Dates are along the bottom, magnitudes at left. If the trend continues, Nova Sgr #2 could outshine the 2013 nova in Delphinus very soon. Credit: AAVSO

Novae occur in binary star systems where a tiny but gravitationally powerful white dwarf star pulls gases from a close companion star. The material piles up in a thin layer on the dwarf’s hot surface, fuses and burns explosively to create the explosion we dub a nova. Spectra of the expanding debris envelope reveal the imprint of hydrogen gas and as well as ionized iron.

Nova illustration with an expanding cloud of debris surrounding central fireball emitting red hydrogen-alpha light. — Artist’s view of a nova with an expanding cloud of debris surrounding the central fireball emitting red hydrogen-alpha light.

Shortly after discovery, the nova’s debris shell was expanding at the rate of ~1,740 miles per second (2,800 km/sec) or more than 6.2 million mph (10 million mph). It’s since slowed to about half that rate. Through a telescope the star glows pale yellow but watch for its color to deepen to yellow orange and even red. Right now, it’s still in the fireball phase, with the dwarf star hidden by an envelope of fiery hydrogen gas.

As novae evolve, they’ll often turn from white or yellow to red. Emission of deep red light from hydrogen atoms – called hydrogen alpha – gives them their warm, red color. Hydrogen, the most common element in stars, gets excited through intense radiation or collisions with atoms (heat) and re-emits a ruby red light when it returns to its rest state. Astronomers see the light as bright red emission line in the star’s spectrum. Spectra of the nova show additional emission lines of hydrogen beta or H-beta (blue light emitted by hydrogen) and iron.

There are actually several reasons why novae rouge up over time, according to former AAVSO director Arne Henden:

“Energy from the explosion gets absorbed by the surrounding material in a nova and re-emitted as H-alpha,” said Henden. Not only that but as the explosion expands over time, the same amount of energy is spread over a larger area.

“The temperature drops,” said Henden, “causing the fireball to cool and turn redder on its own.” As the eruption expands and cools, materials blasted into the surrounding space condense into a shell of soot that absorbs that reddens the nova much the same way dusty air reddens the Sun.

Nova Sagittarii’s current pale yellow color results from seeing a mix of light – blue from the explosion itself plus red from the expanding fireball. As for its distance from Earth, I haven’t heard, but given that the progenitor star was 15th magnitude or possibly fainter, we’re probably talking in the thousands of light years.

Wide view of the Sagittarius-Scorpius region with some of the brighter star clusters and nebulae labeled for binocular browsing. Credit: Bob King

In an earlier article on the nova’s discovery I mentioned taking a look at Saturn as long as you made the effort the get up early. Here’s a photo of the Sagittarius region you can use to help you further your dawn binocular explorations. The entire region is rich with star clusters and nebula, many of which were cataloged long ago by French astronomer Charles Messier, hence the “M” numbers.

February 18, 2015December 23, 2015 by Tim Reyes

A Star Passed Through the Solar System Just 70,000 Years Ago

A binary star system Credit: Michael Osadciw/University of Rochester

Astronomers have reported the discovery of a star that passed within the outer reaches of our Solar System just 70,000 years ago, when early humans were beginning to take a foothold here on Earth. The stellar flyby was likely close enough to have influenced the orbits of comets in the outer Oort Cloud, but Neandertals and Cro Magnons – our early ancestors – were not in danger. But now astronomers are ready to look for more stars like this one.

A comparison of the Solar System and its Oort Cloud. 70,000 years ago, Scholz's Star and companion passed along the outer boundaries of our Solar System (Credit: NASA, Michael Osadciw/University of Rochester) — A comparison of the Solar System and its Oort Cloud. 70,000 years ago, Scholz’s Star and companion passed along the outer boundaries of our Solar System (Credit: NASA, Michael Osadciw/University of Rochester, Illustration-T.Reyes)

Lead author Eric Mamajek from the University of Rochester and collaborators report in The Closest Known Flyby Of A Star To The Solar System (published in Astrophysical Journal on February 12, 2015) that “the flyby of this system likely caused negligible impact on the flux of long-period comets, the recent discovery of this binary highlights that dynamically important Oort Cloud perturbers may be lurking among nearby stars.”

The star, named Scholz’s star, was just 8/10ths of a light year at closest approach to the Sun. In comparison, the nearest known star to the Sun is Proxima Centauri at 4.2 light years.

While the internet has been rife with threads and accusations of a Nemesis star that is approaching the inner Solar System and is somehow being “hidden” by NASA, this small red dwarf star with a companion represents the real thing.

In 1984, the paleontologists David Raup and Jack Sepkoski postulated that a dim dwarf star, now widely known on the internet as the Nemesis Star, was in a very long period Solar orbit. The elliptical orbit brought the proposed star into the inner Solar System every 26 million years, causing a rain of comets and mass extinctions on that time period. By no coincidence, because of the sheer numbers of red dwarfs throughout the galaxy, Scholz’s star nearly fits such a scenario. Nemesis was proposed to be in a orbit extending 95,000 A.U. compared to Scholz’s nearest flyby distance of 50,000 A.U. Recent studies of impact rates on Earth, the Moon and Mars have discounted the existence of a Nemesis star (see New Impact Rate Count Lays Nemesis Theory to Rest, Universe Today, 8/1/2011)

But Scholz’s star — a real-life Oort Cloud perturber — was a small red dwarf star star with a M9 spectral classification. M-class stars are the most common star in our galaxy and likely the whole Universe, as 75% of all stars are of this type. Scholz’s is just 15% of the mass of our Sun. Furthermore, Scholz’s is a binary star system with the secondary being a brown dwarf of class T5. Brown Dwarfs are believed to be plentiful in the Universe but due to their very low intrinsic brightness, they are very difficult to discover … except, as in this case, as companions to brighter stars.

The astronomers reported that their survey of new astrometric data of nearby stars identified Scholz’s as an object of interest. The star’s transverse velocity was very low, that is, the stars sideways motion. Additionally, they recognized that its radial velocity – motion towards or away from us, was quite high. For Scholz’s, the star was speeding directly away from our Solar System. How close could Scholz’s star have been to our system in the past? They needed more accurate data.

The collaborators turned to two large telescopes in the southern hemisphere. Spectrographs were employed on the Southern African Large Telescope (SALT) in South Africa and the Magellan telescope at Las Campanas Observatory, Chile. With more accurate trangental and radial velocities, the researchers were able to calculate the trajectory, accounting for the Sun’s and Scholz’s motion around the Milky Way galaxy.

Scholz’s star is an active star and the researchers added that while it was nearby, it shined at a dimly of about 11th magnitude but eruptions and flares on its surface could have raised its brightness to visible levels and could have been seen as a “new” star by primitive humans of the time.

The relative sizes of the inner Solar System, Kuiper Belt and the Oort Cloud. (Credit: NASA, William Crochot)

At present, Scholz’s star is 20 light years away, one of the 70 closest stars to our Solar System. However, the astronomers calculated, with a 98% certainty, that Scholz’s passed within 0.5 light years, approximately 50,000 Astronomical Units (A.U.) of the Sun.

An A.U. is the mean distance from the Earth to the Sun and 50,000 is an important mile marker in our Solar System. It is the outer reaches of the Oort Cloud where billions of comets reside in cold storage, in orbits that take hundreds of thousands of years to circle the Sun.

With this first extraordinary close encounter discovered, the collaborators of this paper as well as other researchers are planning new searches for “Nemesis” type stars. The Large Synoptic Survey Telescope (LSST) and other telescopes within the next decade will bring an incredible array of data sets that will uncover many more red dwarf, brown dwarf and possibly orphan planets roaming in nearby space. Some of these could likewise be traced to past or future near misses to the Sun and Earth system.

January 13, 2015December 23, 2015 by Matt Williams

One of the Milky Way’s Arms Might Encircle the Entire Galaxy

Artist's conception of the Milky Way galaxy as seen from far Galactic North (in Coma Berenices) Credit: NASA/JPL-Caltech/R. Hurt

Given that our Solar System sits inside the Milky Way Galaxy, getting a clear picture of what it looks like as a whole can be quite tricky. In fact, it was not until 1852 that astronomer Stephen Alexander first postulated that the galaxy was spiral in shape. And since that time, numerous discoveries have come along that have altered how we picture it.

For decades astronomers have thought the Milky Way consists of four arms — made up of stars and clouds of star-forming gas — that extend outwards in a spiral fashion. Then in 2008, data from the Spitzer Space Telescope seemed to indicate that our Milky Way has just two arms, but a larger central bar. But now, according to a team of astronomers from China, one of our galaxy’s arms may stretch farther than previously thought, reaching all the way around the galaxy.

This arm is known as Scutum–Centaurus, which emanates from one end of the Milky Way bar, passes between us and Galactic Center, and extends to the other side of the galaxy. For many decades, it was believed that was where this arm terminated.

However, back in 2011, astronomers Thomas Dame and Patrick Thaddeus from the Harvard–Smithsonian Center for Astrophysics spotted what appeared to be an extension of this arm on the other side of the galaxy.

*Star-forming region in interstellar space. Image credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration*

But according to astronomer Yan Sun and colleagues from the Purple Mountain Observatory in Nanjing, China, the Scutum–Centaurus Arm may extend even farther than that. Using a novel approach to study gas clouds located between 46,000 to 67,000 light-years beyond the center of our galaxy, they detected 48 new clouds of interstellar gas, as well as 24 previously-observed ones.

For the sake of their study, Sun and his colleagues relied on radio telescope data provided by the Milky Way Imaging Scroll Painting project, which scans interstellar dust clouds for radio waves emitted by carbon monoxide gas. Next to hydrogen, this gas is the most abundant element to be found in interstellar space – but is easier for radio telescopes to detect.

Combining this information with data obtained by the Canadian Galactic Plane Survey (which looks for hydrogen gas), they concluded that these 72 clouds line up along a spiral-arm segment that is 30,000 light-years in length. What’s more, they claim in their report that: “The new arm appears to be the extension of the distant arm recently discovered by Dame & Thaddeus (2011) as well as the Scutum-Centaurus Arm into the outer second quadrant.”

Ilustration of our galaxy, showing our Sun (red dot) and the possible extension of the Scutum-Centaurus Arm. CREDIT: Modified from "A Possible Extension of the Scutum-Centaurus Arm into the Outer Second Quadrant" by Yan Sun et al., in The Astrophysical Journal Letters, Vol. 798, January 2015; Robert Hurt. NASA/JPL-Caltech/SSC (background spiral). — *Illustration of our galaxy showing the possible extension of the Scutum-Centaurus Arm. CREDIT: Yan Sun/The Astrophysical Journal Letters, Vol. 798/Robert Hurt. NASA/JPL-Caltech/SSC*

This would mean the arm is not only the single largest in our galaxy, but is also the only one to effectively reach 360° around the Milky Way. Such a find would be unprecedented given the fact that nothing of the sort has been observed with other spiral galaxies in our local universe.

Thomas Dame, one of the astronomers who discovered the possible extension of the Scutum-Centaurus Arm in 2011, was quoted by Scientific American as saying: “It’s rare. I bet that you would have to look through dozens of face-on spiral galaxy images to find one where you could convince yourself you could track one arm 360 degrees around.”

Naturally, the prospect presents some problems. For one, there is an apparent gap between the segment that Dame and Thaddeus discovered in 2011 and the start of the one discovered by the Chinese team – a 40,000 light-year gap to be exact. This could mean that the clouds that Sun and his colleagues discovered may not be part of the Scutum-Centaurus Arm after all, but an entirely new spiral-arm segment.

If this is true, than it would mean that our Galaxy has several “outer” arm segments. On the other hand, additional research may close that gap (so to speak) and prove that the Milky Way is as beautiful when seen afar as any of the spirals we often observe from the comfort of our own Solar System.

Further Reading: arXiv Astrophysics, The Astrophysical Letters

January 6, 2015December 23, 2015 by Vanessa Janek

Hearing the Early Universe’s Scream: Sloan Survey Announces New Findings

A still photo from an animated flythrough of the universe using SDSS data. This image shows our Milky Way Galaxy. The galaxy shape is an artist’s conception, and each of the small white dots is one of the hundreds of thousands of stars as seen by the SDSS. Image credit: Dana Berry / SkyWorks Digital, Inc. and Jonathan Bird (Vanderbilt University)

Imagine a single mission that would allow you to explore the Milky Way and beyond, investigating cosmic chemistry, hunting planets, mapping galactic structure, probing dark energy and analyzing the expansion of the wider Universe. Enter the Sloan Digital Sky Survey, a massive scientific collaboration that enables one thousand astronomers from 51 institutions around the world to do just that.

At Tuesday’s AAS briefing in Seattle, researchers announced the public release of data collected by the project’s latest incarnation, SDSS-III. This data release, termed “DR12,” represents the survey’s largest and most detailed collection of measurements yet: 2,000 nights’ worth of brand-new information about nearly 500 million stars and galaxies.

One component of SDSS is exploring dark energy by “listening” for acoustic oscillation signals from the the acceleration of the early Universe, and the team also shared a new animated “fly-through” of the Universe that was created using SDSS data.

The SDSS-III collaboration is based at the powerful 2.5-meter Sloan Foundation Telescope at the Apache Point Observatory in New Mexico. The project itself consists of four component surveys: BOSS, APOGEE, MARVELS, and SEGUE. Each of these surveys applies different trappings to the parent telescope in order to accomplish its own, unique goal.

BOSS (the Baryon Oscillation Spectroscopic Survey) visualizes the way that sound waves produced by interacting matter in the early Universe are reflected in the large-scale structure of our cosmos. These ancient imprints, which date back to the first 500,000 years after the Big Bang, are especially evident in high-redshift objects like luminous-red galaxies and quasars. Three-dimensional models created from BOSS observations will allow astronomers to track the expansion of the Universe over a span of 9 billion years, a feat that, later this year, will pave the way for rigorous assessment of current theories regarding dark energy.

At the press briefing, Daniel Eistenstein from the Harvard-Smithsonian Center for Astrophysics explained how BOSS requires huge volumes of data and that so far 1.4 million galaxies have been mapped. He indicated the data analyzed so far strongly confirm dark energy’s existence.

This tweet from the SDSS twitter account uses a bit of humor to explain how BOSS works:

It turns out that in space, everyone can hear you scream, if you do it in the early Universe and set up acoustic oscillations #aas225

— SDSS — J. Johnson (@sdssurveys) January 6, 2015

APOGEE (the Apache Point Observatory Galactic Evolution Experiment) employs a sophisticated, near-infrared spectrograph to pierce through thick dust and gather light from 100,000 distant red giants. By analyzing the spectral lines that appear in this light, scientists can identify the signatures of 15 different chemical elements that make up the faraway stars – observations that will help researchers piece together the stellar history of our galaxy.

MARVELS (the Multi-Object APO Radial Velocity Exoplanet Large-Area Survey) identifies minuscule wobbles in the orbits of stars, movements that betray the gravitational influence of orbiting planets. The technology itself is unprecedented. “MARVELS is the first large-scale survey to measure these tiny motions for dozens of stars simultaneously,” explained the project’s principal investigator Jian Ge, “which means we can probe and characterize the full population of giant planets in ways that weren’t possible before.”

At the press briefing, Ge said that MARVELS observed 5,500 stars repeatedly, looking for giant exoplanets around these stars. So far, the data has revealed 51 giant planet candidates as well as 38 brown dwarf candidates. Ge added that more will be found with better data processing.

A still photo from an animated flythrough of the universe using SDSS data. This image shows a small part of the large-scale structure of the universe as seen by the SDSS -- just a few of many millions of galaxies. The galaxies are shown in their proper positions from SDSS data. Image credit: Dana Berry / SkyWorks Digital, Inc. — A still photo from an animated flythrough of the universe using SDSS data. This image shows a small part of the large-scale structure of the universe as seen by the SDSS — just a few of many millions of galaxies. The galaxies are shown in their proper positions from SDSS data. Image credit: Dana Berry / SkyWorks Digital, Inc.

SEGUE (the Sloan Extension for Galactic Understanding and Exploration) rounds out the quartet by analyzing visible light from 250,000 stars in the outer reaches of our galaxy. Coincidentally, this survey’s observations “segue” nicely into work being done by other projects within SDSS-III. Constance Rockosi, leader of the SDSS-III domain of SEGUE, recaps the importance of her project’s observations of our outer galaxy: “In combination with the much more detailed view of the inner galaxy from APOGEE, we’re getting a truly holistic picture of the Milky Way.”

One of the most exceptional attributes of SDSS-III is its universality; that is, every byte of juicy information contained in DR12 will be made freely available to professionals, amateurs, and lay public alike. This philosophy enables interested parties from all walks of life to contribute to the advancement of astronomy in whatever capacity they are able.

As momentous as the release of DR12 is for today’s astronomers, however, there is still much more work to be done. “Crossing the DR12 finish line is a huge accomplishment by hundreds of people,” said Daniel Eisenstein, director of the SDSS-III collaboration, “But it’s a big universe out there, so there is plenty more to observe.”

DR12 includes observations made by SDSS-III between July 2008 and June 2014. The project’s successor, SDSS-IV, began its run in July 2014 and will continue observing for six more years.

Here is the video animation of the fly-through of the Universe:

December 31, 2014December 23, 2015 by Nancy Atkinson

Leave Home: Hypnotic Milky Way Timelapse from New Zealand

Night sky view from New Zealand. Credit and copyright: Manoj Kesavan.

Photographer Manoj Kesavan has been working on this timelapse since mid-2013 and the results are stunning and spellbinding. ‘Leave Home’ was shot from many locations in Palmerston North, New Zealand in 2013 then continued in 2014 from Taupo and Auckland. Early in the timelapse you’ll see daytime views of the New Zealand landscape but midway, the night views kick in. Hang on while watching some of the spinning Milky Way shots, and the wave scenes might leave you hypnotized! All in all, this is a gorgeous look at the land, sea and skies of New Zealand.

The images were shot with Canon 20D, Canon 7D & 60D with various Canon & Sigma Lenses and batch processed with Lightroom 5. Motion control was achieved by Dynamic Perception stage one dolly & Emotimo TB3 Black.

See more of Kesavan’s work on Flickr and Facebook.

L E A V E H O M E – A NEW ZEALAND TIMELAPSE PROJECT from Manoj Kesavan on Vimeo.

December 11, 2014December 23, 2015 by Vanessa Janek

Gamma Ray Bursts Limit The Habitability of Certain Galaxies, Says Study

An artistic image of the explosion of a star leading to a gamma-ray burst. (Source: FUW/Tentaris/Maciej Fro?ow)

Gamma ray bursts (GRBs) are some of the brightest, most dramatic events in the Universe. These cosmic tempests are characterized by a spectacular explosion of photons with energies 1,000,000 times greater than the most energetic light our eyes can detect. Due to their explosive power, long-lasting GRBs are predicted to have catastrophic consequences for life on any nearby planet. But could this type of event occur in our own stellar neighborhood? In a new paper published in Physical Review Letters, two astrophysicists examine the probability of a deadly GRB occurring in galaxies like the Milky Way, potentially shedding light on the risk for organisms on Earth, both now and in our distant past and future.

There are two main kinds of GRBs: short, and long. Short GRBs last less than two seconds and are thought to result from the merger of two compact stars, such as neutron stars or black holes. Conversely, long GRBs last more than two seconds and seem to occur in conjunction with certain kinds of Type I supernovae, specifically those that result when a massive star throws off all of its hydrogen and helium during collapse.

Perhaps unsurprisingly, long GRBs are much more threatening to planetary systems than short GRBs. Since dangerous long GRBs appear to be relatively rare in large, metal-rich galaxies like our own, it has long been thought that planets in the Milky Way would be immune to their fallout. But take into account the inconceivably old age of the Universe, and “relatively rare” no longer seems to cut it.

In fact, according to the authors of the new paper, there is a 90% chance that a GRB powerful enough to destroy Earth’s ozone layer occurred in our stellar neighborhood some time in the last 5 billion years, and a 50% chance that such an event occurred within the last half billion years. These odds indicate a possible trigger for the second worst mass extinction in Earth’s history: the Ordovician Extinction. This great decimation occurred 440-450 million years ago and led to the death of more than 80% of all species.

Today, however, Earth appears to be relatively safe. Galaxies that produce GRBs at a far higher rate than our own, such as the Large Magellanic Cloud, are currently too far from Earth to be any cause for alarm. Additionally, our Solar System’s home address in the sleepy outskirts of the Milky Way places us far away from our own galaxy’s more active, star-forming regions, areas that would be more likely to produce GRBs. Interestingly, the fact that such quiet outer regions exist within spiral galaxies like our own is entirely due to the precise value of the cosmological constant – the factor that describes our Universe’s expansion rate – that we observe. If the Universe had expanded any faster, such galaxies would not exist; any slower, and spirals would be far more compact and thus, far more energetically active.

In a future paper, the authors promise to look into the role long GRBs may play in Fermi’s paradox, the open question of why advanced lifeforms appear to be so rare in our Universe. A preprint of their current work can be accessed on the ArXiv.