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A different astronomy and space science related image is featured each day, along with a brief explanation.
Closest Star has Potentially Habitable Planet
The star closest to the Sun has a planet similar to the Earth. As announced yesterday, recent observations confirmed that this planet not only exists but inhabits a zone where its surface temperature could allow liquid water, a key ingredient for life on Earth. It is not yet known if this planet, Proxima b, has any life. Even if not, its potential ability to sustain liquid water might make it a good first hop for humanity's future trips out into the Milky Way Galaxy. Although the planet's parent star, Proxima Centauri, is cooler and redder than our Sun, one of the other two stars in the Alpha Centauri star system is very similar to our Sun. The featured image shows the sky location of Proxima Centauri in southern skies behind the telescope that made many of the discovery observations: ESO's 3.6-meter telescope in La Silla, Chile. The discovered planet orbits close in -- so close one year there takes only 11 days on Earth. The planet was discovered by the ESO's Pale Red Dot collaboration. Although seemingly unlikely, if Proxima b does have intelligent life, at 4.25 light years distance it is close enough to Earth for two-way communication.
Gamma rays and Comet Dust
Gamma-rays and dust from periodic Comet Swift-Tuttle plowed through planet Earth's atmosphere on the night of August 11/12. Impacting at about 60 kilometers per second the grains of comet dust produced this year's remarkably active Perseid meteor shower. This composite wide-angle image of aligned shower meteors covers a 4.5 hour period on that Perseid night. In it the flashing meteor streaks can be traced back to the shower's origin on the sky. Alongside the Milky Way in the constellation Perseus, the radiant marks the direction along the perodic comet's orbit. Traveling at the speed of light, cosmic gamma-rays impacting Earth's atmosphere generated showers too, showers of high energy particles. Just as the meteor streaks point back to their origin, the even briefer flashes of light from the particles can be used to reconstruct the direction of the particle shower, to point back to the origin on the sky of the incoming gamma-ray. Unlike the meteors, the incredibly fast particle shower flashes can't be followed by eye. But both can be followed by the high speed cameras on the multi-mirrored dishes in the foreground. Of course, the dishes are MAGIC (Major Atmospheric Gamma Imaging Cherenkov) telescopes, an Earth-based gamma-ray observatory on the Canary Island of La Palma.
Meteor before Galaxy
What's that green streak in front of the Andromeda galaxy? A meteor. While photographing the Andromeda galaxy last Friday, near the peak of the Perseid Meteor Shower, a sand-sized rock from deep space crossed right in front of our Milky Way Galaxy's far-distant companion. The small meteor took only a fraction of a second to pass through this 10-degree field. The meteor flared several times while braking violently upon entering Earth's atmosphere. The green color was created, at least in part, by the meteor's gas glowing as it vaporized. Although the exposure was timed to catch a Perseids meteor, the orientation of the imaged streak seems a better match to a meteor from the Southern Delta Aquariids, a meteor shower that peaked a few weeks earlier.
The Keyhole in the Carina Nebula
The dark dusty Keyhole Nebula gets its name from its unusual shape. The looping Keyhole, in this featured classic image by the Hubble Space Telescope, is a smaller region inside the larger Carina Nebula. Dramatic dark dust knots and complex features are sculpted by the winds and radiation of the Carina Nebula's many massive and energetic stars. In particular, the shape of the dust cloud on the upper left of the Keyhole Nebula may stimulate the human imagination to appear similar to, for example, a superhero flying through a cloud, arm up, with a saved person in tow below. The region lies about 7,500 light-years away in planet Earth's southern sky. The Keyhole Nebula was created by the dying star Eta Carina , out of the frame, which is prone to violent outbursts during its final centuries.
Perseid, Aurora, and Noctilucent Clouds
Night skies over northern Sweden can hold some tantalizing sights in August. Gazing toward the Big Dipper, this beautiful skyscape captures three of them in a single frame taken last August 12/13. Though receding from northern skies for the season, night shining or noctilucent clouds are hanging just above the horizon. Extreme altitude icy condensations on meteoric dust, they were caught here just below an early apparition of a lovely green auroral band, also shining near the edge of space. The flash of a Perseid meteor near the peak of the annual shower punctuates the scene. In fact, this year's Perseid shower will peak in the coming days, offering a continuing chance for a night sky photographer's hat trick.
Las Campanas Moon and Mercury
Last Thursday the view toward sunset from the 2.5 kilometer summit of Cerro Las Campanas in the remote Chilean Andes was amazing. Bright but fading Mercury stood very close to a two day old Moon. Both a sunlit lunar crescent and earthlit lunar nightside are captured with the fleeting innermost planet in this breathtaking mountainscape. Even below the conjunction of Moon and Mercury, a close pairing of brilliant Venus and bright star Regulus hangs in the sky, still above the colorful western horizon. Of course amazing skies above Las Campanas are not unexpected. The region is currently home to the twin Magellan telescopes of the Las Campanas Observatory and the summit location is the site of the future Giant Magellan Telescope.
Behold the Universe
What if you climbed up on a rock and discovered the Universe? You can. Although others have noted much of it before, you can locate for yourself stars, planets, and even the plane of our Milky Way Galaxy. All you need is a dark clear sky -- the rock is optional. If you have a camera, you can further image faint nebulas, galaxies, and long filaments of interstellar dust. If you can process digital images, you can bring out faint features, highlight specific colors, and merge foreground and background images. In fact, an industrious astrophotographer has done all of these to create the presented picture. All of the component images were taken early last month on the same night within a few meters of each other. The picturesque setting was Sand Beach in Stonington, Maine, USA with the camera pointed south over Penobscot Bay.
Ripples Through a Dark Sky
Sunlight ripples through a dark sky on this Swedish summer midnight as noctilucent or night shining clouds seem to imitate the river below. In fact, the seasonal clouds often appear at high latitudes in corresponding summer months. Also known as polar mesospheric clouds, they form as water vapor is driven into the cold upper atmosphere. Fine dust supplied by disintegrating meteors or volcanic ash provides sites where water vapor can condense, turning to ice at the cold temperatures in the mesosphere. Poised at the edge of space some 80 kilometers above, these icy clouds really do reflect sunlight toward the ground. They are visible here even though the Sun itself was below the horizon, as seen on July 16 from Sweden's Färnebofjärdens National Park.
M13: A Great Globular Cluster of Stars
M13 is one of the most prominent and best known globular clusters. Visible with binoculars in the constellation of Hercules, M13 is frequently one of the first objects found by curious sky gazers seeking celestials wonders beyond normal human vision. M13 is a colossal home to over 100,000 stars, spans over 150 light years across, lies over 20,000 light years distant, and is over 12 billion years old. At the 1974 dedication of Arecibo Observatory, a radio message about Earth was sent in the direction of M13. The featured image in HDR, taken through a small telescope, spans an angular size just larger than a full Moon, whereas the inset image, taken by Hubble Space Telescope, zooms in on the central 0.04 degrees.
Deep Magellanic Clouds Image Indicates Collisions
Did the two most famous satellite galaxies of our Milky Way Galaxy once collide? No one knows for sure, but a detailed inspection of deep images like that featured here give an indication that they have. Pictured, the Large Magellanic Cloud (LMC) is on the top left and the Small Magellanic Cloud (SMC) is on the bottom right. The surrounding field is monochrome color-inverted to highlight faint filaments, shown in gray. Perhaps surprisingly, the featured research-grade image was compiled with small telescopes to cover the large angular field -- nearly 40 degrees across. Much of the faint nebulosity is Galactic Cirrus clouds of thin dust in our own Galaxy, but a faint stream of stars does appear to be extending from the SMC toward the LMC. Also, stars surrounding the LMC appear asymmetrically distributed, indicating in simulations that they could well have been pulled off gravitationally in one or more collisions. Both the LMC and the SMC are visible to the unaided eye in southern skies. Future telescopic observations and computer simulations are sure to continue in a continuing effort to better understand the history of our Milky Way and its surroundings.
Falcon 9: Launch and Landing
Shortly after midnight on July 18 a SpaceX Falcon 9 rocket launched from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida, planet Earth. About 9 minutes later, the rocket's first stage returned to the spaceport. This single time exposure captures the rocket's launch arc and landing streak from Jetty Park only a few miles away. Along a climbing, curving trajectory the launch is traced by the initial burn of the first stage, ending near the top of the bright arc before stage separation. Due to perspective the next bright burn appears above the top of the launch arc in the photo, the returning first stage descending closer to the Cape. The final landing burn creates a long streak as the first stage slows and comes to rest at Landing Zone 1. Yesterday the Dragon cargo spacecraft delivered to orbit by the rocket's second stage was attached to the International Space Station.
The Orion Nebula in Infrared from HAWK I
The deepest infrared image of the Orion Nebula has uncovered a bonanza of previously unknown low-mass stars and -- quite possibly -- free floating planets. The picturesque nebula is best known in visible light where it shows a many bright stars and bright glowing gas. Catalogued as M42, the Orion Nebula at a distance of 1300 light years is the closest major star forming region to Earth. One can peer into Orion's pervasive dust in infrared light, as was done again recently with the sophisticated HAWK-I camera attached to one of the European Southern Observatory's Very Large Telescopes in the high mountains of Chile. High resolution versions of the featured infrared deep image show many points of light, many of which are surely brown dwarf stars but some of which are best fit by an unexpectedly high abundance of free-floating planets. Understanding how these low mass objects formed is important to understanding star formation generally and may even help humanity to better understand the early years of our Solar System.
NGC 2736: The Pencil Nebula
Moving from top to bottom in the frame near the center of this sharply detailed color composite, thin, bright, braided filaments are actually long ripples in a cosmic sheet of glowing gas seen almost edge-on. The shock wave plows through interstellar space at over 500,000 kilometers per hour. Cataloged as NGC 2736, its elongated appearance suggests its popular name, the Pencil Nebula. The Pencil Nebula is about 5 light-years long and 800 light-years away, but represents only a small part of the Vela supernova remnant. The Vela remnant itself is around 100 light-years in diameter, the expanding debris cloud of a star that was seen to explode about 11,000 years ago. Initially, the shock wave was moving at millions of kilometers per hour but has slowed considerably, sweeping up surrounding interstellar material. In the narrowband, wide field image, red and blue-green colors track the characteristic glow of ionized hydrogen and oxygen atoms.
Chasing Juno
Wait for me! In 2011, NASA's robotic mission Juno launched for Jupiter from Cape Canaveral, Florida, USA. Last week, Juno reached Jupiter and fired internal rockets to become only the second spacecraft to orbit our Solar System's largest planet. Juno, tasked with studying the jovian giant over the next two years, is in a highly elliptical orbit that will next bringing it near Jupiter's cloud tops in late August. Of course, the three-year-old pictured was not able to catch up to the launching rocket. Today, however, five years later, he is eight-years-old and still chasing rockets -- in that now he wants to be an astronaut.
Moon Meets Jupiter
What's that next to the Moon? Jupiter -- and its four largest moons. Skygazers around planet Earth enjoyed the close encounter of planets and Moon in 2012 July 15's predawn skies. And while many saw bright Jupiter next to the slender, waning crescent, Europeans also had the opportunity to watch the ruling gas giant pass behind the lunar disk, occulted by the Moon as it slid through the night. Clouds threaten in this telescopic view from Montecassiano, Italy, but the frame still captures Jupiter after it emerged from the occultation along with all four of its large Galilean moons. The sunlit crescent is overexposed with the Moon's night side faintly illuminated by Earthshine. Lined up left to right beyond the dark lunar limb are Callisto, Ganymede, Jupiter, Io, and Europa. In fact, Callisto, Ganymede, and Io are larger than Earth's Moon, while Europa is only slightly smaller. Last week, NASA's Juno became the second spacecraft ever to orbit Jupiter.
Gigantic Jet Lightning over China
That's no meteor. While watching and photographing this year's Perseid Meteor Shower, something unexpected happened: a gigantic jet erupted from a nearby cloud. The whole thing was over in a flash -- it lasted less than a second -- but was fortunately captured by an already-recording digital camera. Gigantic jets are a rare form of lightning recognized formally only a few years ago. The featured high resolution color image, taken near the peak of Shikengkong mountain in China, may be the best image yet of this unusual phenomenon. The same event appears to have been captured simultaneously by another photographer, further away. The gigantic jet appears to start somewhere in a nearby thundercloud and extend upwards towards Earth's ionosphere. The nature of gigantic jets and their possible association with other types of Transient Luminous Events (TLEs) such as blue jets and red sprites remains an active topic of research.
Perseid Fireball at Sunset Crater
On the night of August 12, this bright Perseid meteor flashed above volcanic Sunset Crater National Monument, Arizona, USA, planet Earth. Streaking along the summer Milky Way, its initial color is likely due to the shower meteor's characteristically high speed. Entering at 60 kilometers per second, Perseid meteors are capable of exciting green emission from oxygen atoms while passing through the tenuous atmosphere at high altitudes. Also characteristic of bright meteors, this Perseid left a visibly glowing persistent train. Its evolution is seen over a three minute sequence (left to right) spanning the bottom of the frame. The camera ultimately captured a dramatic timelapse video of the twisting, drifting train.
Human as Spaceship
You are a spaceship soaring through the universe. So is your dog. We all carry with us trillions of microorganisms as we go through life. These multitudes of bacteria, fungi, and archaea have different DNA than you. Collectively called your microbiome, your shipmates outnumber your own cells. Your crew members form communities, help digest food, engage in battles against intruders, and sometimes commute on a liquid superhighway from one end of your body to the other. Much of what your microbiome does, however, remains unknown. You are the captain, but being nice to your crew may allow you to explore more of your local cosmos.
The Easterbunny Comes to NGC 4725
At first called "Easterbunny" by its discovery team, officially named Makemake is the second brightest dwarf planet of the Kuiper belt. The icy world appears twice in this astronomical image, based on data taken on June 29 and 30 of the bright spiral galaxy NGC 4725. Makemake is marked by short red lines, its position shifting across a homemade telescope's field-of-view over two nights along a distant orbit. On those dates nearly coincident with the line-of-sight to the spiral galaxy in the constellation Coma Berenices, Makemake was about 52.5 astronomical units or 7.3 light-hours away. NGC 4725 is over 100,000 light-years across and 41 million light-years distant. Makemake is now known to have at least one moon. NGC 4725 is a famous one-armed spiral galaxy.
Io: Moon over Jupiter
How big is Jupiter's moon Io? The most volcanic body in the Solar System, Io (usually pronounced "EYE-oh") is 3,600 kilometers in diameter, about the size of planet Earth's single large natural satellite. Gliding past Jupiter at the turn of the millennium, the Cassini spacecraft captured this awe inspiring view of active Io with the largest gas giant as a backdrop, offering a stunning demonstration of the ruling planet's relative size. Although in the featured picture Io appears to be located just in front of the swirling Jovian clouds, Io hurtles around its orbit once every 42 hours at a distance of 420,000 kilometers or so from the center of Jupiter. That puts Io nearly 350,000 kilometers above Jupiter's cloud tops, roughly equivalent to the distance between Earth and Moon. In July, NASA's Juno satellite began orbiting Jupiter and will sometimes swoop to within 5,000 kilometers of Jupiter's cloud tops.
Apollo 15 Panorama
On July 31, 1971, Apollo 15 astronauts Jim Iwrin and Dave Scott deployed the first Lunar Roving Vehicle on the Moon. Using it to explore their Hadley-Apennine landing site they spent nearly three days on the Moon while Al Worden orbited above. This digitally stitched panorama shows Scott examining a boulder on the slope of 3.5 kilometer high Mons Hadley Delta to the left of their electric-powered, four-wheel drive vehicle. The sun at his back, Irwin casts the strong shadow to the rover's right. The panoramic view extends farther right to the sunward direction, over Hadley Rille and lunar terrain, revealed in harsh, unfiltered sunlight. In total, the rover traversed 28 kilometers (17 miles) on the lunar surface. The Apollo 15 mission returned about 76 kilograms of moon rocks to planet Earth.
Behind Saturn
What's behind Saturn? The first answer is the camera itself, perched on the Cassini spacecraft currently orbiting behind the planet with the most grand ring system in our Solar System. The unusual perspective places Cassini on the far side of Saturn from the Sun so that more than half of Saturn appears dark -- a perspective that no Earth-based observer could achieve. Behind Saturn, in the context of the featured infrared image, is Saturn's moon Tethys, visible as the small speck above the unusual hexagonal cloud pattern that encompasses Saturn's North Pole. Tethys actually orbits Saturn right in the ring plane, which places the 1000-km moon much farther from Cassini than the planet itself. Cassini has been studying Saturn and its moons for 12 years, but, unfortunately, its amazing mission will soon come to an end. In order to protect life that may exist on or inside Saturn's moons, the robotic spacecraft will be directed to crash into Saturn's thick atmosphere next September.
Herschel's Eagle Nebula
A now famous picture from the Hubble Space Telescope featured Pillars of Creation, star forming columns of cold gas and dust light-years long inside M16, the Eagle Nebula. This false-color composite image views the nearby stellar nursery using data from the Herschel Space Observatory's panoramic exploration of interstellar clouds along the plane of our Milky Way galaxy. Herschel's far infrared detectors record the emission from the region's cold dust directly. The famous pillars are included near the center of the scene. While the central group of hot young stars is not apparent at these infrared wavelengths, the stars' radiation and winds carve the shapes within the interstellar clouds. Scattered white spots are denser knots of gas and dust, clumps of material collapsing to form new stars. The Eagle Nebula is some 6,500 light-years distant, an easy target for binoculars or small telescopes in a nebula rich part of the sky toward the split constellation Serpens Cauda (the tail of the snake).
Puzzling a Sky over Argentina
Can you find the comet? True, a careful eye can find thousands of stars, tens of constellations, four planets, three galaxies, and the central band of our Milky Way Galaxy -- all visible in the sky of this spectacular 180-degree panorama. Also, if you know what to look for, you can identify pervasive green airglow, an earthly cloud, the south celestial pole, and even a distant cluster of stars. But these are all easier to find than Comet 252P/LINEAR. The featured image, taken in el Leoncito National Park, Argentina in early April, also features the dome of the Jorge Sahade telescope on the hill on the far right. Have you found the comet yet? If so, good for you (it was the green spot on the left), but really the harder thing to find is Small Cloud of Magellan.
M2 9: Wings of a Butterfly Nebula
Are stars better appreciated for their art after they die? Actually, stars usually create their most artistic displays as they die. In the case of low-mass stars like our Sun and M2-9 pictured above, the stars transform themselves from normal stars to white dwarfs by casting off their outer gaseous envelopes. The expended gas frequently forms an impressive display called a planetary nebula that fades gradually over thousands of years. M2-9, a butterfly planetary nebula 2100 light-years away shown in representative colors, has wings that tell a strange but incomplete tale. In the center, two stars orbit inside a gaseous disk 10 times the orbit of Pluto. The expelled envelope of the dying star breaks out from the disk creating the bipolar appearance. Much remains unknown about the physical processes that cause planetary nebulae.
Dark Dunes on Mars
How does wind affect sand on Mars? To help find out if it differs significantly from Earth, the robotic Curiosity rover on Mars was directed to investigate the dark Namib Dune in the Bagnold Dune Field in Gale Crater. Namib is the first active sand dune investigated up close outside of planet Earth. Wind-created ripples on Earth-bound sand dunes appear similar to ripples on Mars, with one exception. The larger peaks visible on dark Namib dune, averaging about 3 meters apart, are of a type seen only underwater on Earth. They appear to arise on Mars because of the way the thin Martian wind drags dark sand particles. The featured image was taken last December and is horizontally compressed to show context. In the distance, a normal dusty Martian landscape slopes up in light orange, while a rock-strewn landscape is visible on the far right. Curiosity unexpectedly went into safe mode in early July, but it was brought out last week and has now resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life.
Mercury on the Horizon
Have you ever seen the planet Mercury? Because Mercury orbits so close to the Sun, it never wanders far from the Sun in Earth's sky. If trailing the Sun, Mercury will be visible low on the horizon for only a short while after sunset. If leading the Sun, Mercury will be visible only shortly before sunrise. So at certain times of the year, informed skygazers with a little determination can usually pick Mercury out from a site with an unobscured horizon. Above, a lot of determination has been combined with a little digital manipulation to show Mercury's successive positions during March of 2000. Each picture was taken from the same location in Spain when the Sun itself was 10 degrees below the horizon and superposed on the single most photogenic sunset. Currently, Mercury is rising higher above the horizon with each passing sunset, and just now is angularly very close to the brighter planet Venus.
M7: Open Star Cluster in Scorpius
M7 is one of the most prominent open clusters of stars on the sky. The cluster, dominated by bright blue stars, can be seen with the naked eye in a dark sky in the tail of the constellation of the Scorpion (Scorpius). M7 contains about 100 stars in total, is about 200 million years old, spans 25 light-years across, and lies about 1000 light-years away. The featured wide-angle image was taken near the city of Belo Horizonte in Brazil. The M7 star cluster has been known since ancient times, being noted by Ptolemy in the year 130 AD. Also visible are a dark dust cloud on the lower right, and, in the background, literally millions of unrelated stars towards the Galactic center.
Aurorae on Jupiter
Jupiter has aurorae. Like Earth, the magnetic field of the gas giant funnels charged particles released from the Sun onto the poles. As these particles strike the atmosphere, electrons are temporarily knocked away from existing gas molecules. Electric force attracts these electrons back. As the electrons recombine to remake neutral molecules, auroral light is emitted. In the featured recently released composite image by the Hubble Space Telescope taken in ultraviolet light, the aurorae appear as annular sheets around the pole. Unlike Earth's aurorae, Jupiter's aurorae include several bright streaks and dots. Jupiter's Great Red Spot is visible on the lower right. Recent aurorae on Jupiter have been particularly strong -- a fortunate coincide with the arrival of NASA's Juno spacecraft at Jupiter last week. Juno was able to monitor the Solar Wind as it approached Jupiter, enabling a better understanding of aurorae in general, including on Earth.
Noctilucent Clouds Tour France
Bright noctilucent or night shining clouds are not familiar sights from northern France. But these electric-blue waves coursed through skies over the small town of Wancourt in Pas-de-Calais on July 6, just before the dawn. From the edge of space, about 80 kilometers above Earth's surface, the icy clouds still reflect sunlight even though the Sun itself is below the horizon as seen from the ground. Usually spotted at high latitudes in summer months the diaphanous apparitions are also known as polar mesospheric clouds. The seasonal clouds are understood to form as water vapor driven into the cold upper atmosphere condenses on the fine dust particles supplied by disintegrating meteors or volcanic ash. NASA's AIM mission provides projections of the noctilucent clouds as seen from space.
