Close Mars Close Mars

Still bright in evening skies, Mars was just past opposition and closest to Earth on July 31, a mere 57.6 million kilometers away. Captured only a week later, this remarkable image shows the Red Planet's disk near its maximum size in earthbound telescopes, but still less than 1/74th the apparent diameter of a Full Moon. Broad regional surface shadings are starting to reappear in the tantalizing view as the latest planet-wide dust storm subsides. With the bright south polar cap at the bottom, the Valles Marineris extends along the center of the disk. Just below it lies the roughly circular Solis Lacus region sometimes known as the Eye of Mars. In a line, three prominent dark spots left of center are the volcanic Tharsis Montes. via NASA https://ift.tt/2oqFPhw

Nearby Cepheid Variable RS Pup Nearby Cepheid Variable RS Pup

In the center is one of the most important stars on the sky. This is partly because, by coincidence, it is surrounded by a dazzling reflection nebula. Pulsating RS Puppis, the brightest star in the image center, is some ten times more massive than our Sun and on average 15,000 times more luminous. In fact, RS Pup is a Cepheid type variable star, a class of stars whose brightness is used to estimate distances to nearby galaxies as one of the first steps in establishing the cosmic distance scale. As RS Pup pulsates over a period of about 40 days, its regular changes in brightness are also seen along the nebula delayed in time, effectively a light echo. Using measurements of the time delay and angular size of the nebula, the known speed of light allows astronomers to geometrically determine the distance to RS Pup to be 6,500 light-years, with a remarkably small error of plus or minus 90 light-years. An impressive achievement for stellar astronomy, the echo-measured distance also more accurately establishes the true brightness of RS Pup, and by extension other Cepheid stars, improving the knowledge of distances to galaxies beyond the Milky Way. The featured image was taken by the Hubble Space Telescope. via NASA https://ift.tt/2worR46

Sea and Sky Glows over the Oregon Coast Sea and Sky Glows over the Oregon Coast

Every step caused the sand to light up blue. That glow was bioluminescence -- a blue radiance that also lights the surf in this surreal scene captured last month at Meyer's Creek Beach in Oregon, USA. Volcanic stacks dot the foreground sea, while a thin fog layer scatters light on the horizon. The rays of light spreading from the left horizon were created by car headlights on the Oregon Coast Highway (US 101), while the orange light on the right horizon emanates from a fishing boat. Visible far in the distance is the band of our Milky Way Galaxy, appearing to rise from a dark rocky outcrop. Sixteen images were added together to bring up the background Milky Way and to reduce noise. via NASA https://ift.tt/2PadW8M

Total Solar Eclipse Shadow from a Balloon Total Solar Eclipse Shadow from a Balloon

Where were you during the Great American Eclipse of 2017? A year ago last week, over 100 million of people in North America went outside to see a partial eclipse of the Sun, while over ten million drove across part of the USA to see the Sun completely disappear behind the Moon -- a total solar eclipse. An estimated 88 percent of American adults saw the eclipse either personally or electronically. One of the better photographed events in human history, images from the eclipse included some unusual vistas, such as from balloons floating in the Earth's stratosphere. About fifty such robotic balloons were launched as part of NASA's Eclipse Ballooning project. Featured is a frame taken from a 360-degree panoramic video captured by one such balloon set aloft in Idaho by students from Brazil in conjunction with NASA and Montana State University. Pictured, the dark shadow of the Moon was seen crossing the Earth below. Although the total eclipse lasted less than three minutes, many who saw it may remember it for a lifetime. Many North Americans will get a another chance to experience a total solar eclipse in 2024. via NASA https://ift.tt/2obXrNS

Fire on Earth Fire on Earth

Sometimes, regions of planet Earth light up with fire. Since fire is the rapid acquisition of oxygen, and since oxygen is a key indicator of life, fire on any planet would be an indicator of life on that planet. Most of the Earth's land has been scorched by fire at some time in the past. Although causing many a tragedy, for many places on Earth fire is considered part of a natural ecosystem cycle. Large forest fires on Earth are usually caused either by humans or lightning and can be visible from orbit. Featured from the year 2000, stunned elk avoid a fire sweeping through Montana's Bitterroot Valley by standing in a river. via NASA https://ift.tt/2NjMEw0

Stripping ESO 137-001 Stripping ESO 137-001

Spiral galaxy ESO 137-001 hurtles through massive galaxy cluster Abell 3627 some 220 million light years away. The distant galaxy is seen in this colorful Hubble/Chandra composite image through a foreground of the Milky Way's stars toward the southern constellation Triangulum Australe. As the spiral speeds along at nearly 7 million kilometers per hour, its gas and dust are stripped away when ram pressure with the cluster's own hot, tenuous intracluster medium overcomes the galaxy's gravity. Evident in Hubble's near visible light data, bright star clusters have formed in the stripped material along the short, trailing blue streaks. Chandra's X-ray data shows off the enormous extent of the heated, stripped gas as diffuse, darker blue trails stretching over 400,000 light-years toward the bottom right. The significant loss of dust and gas will make new star formation difficult for this galaxy. A yellowish elliptical galaxy, lacking in star forming dust and gas, is just to the right of ESO 137-001 in the frame. via NASA https://ift.tt/2Ne73Ct

Messier 20 and 21 Messier 20 and 21

The beautiful Trifid Nebula, also known as Messier 20, is easy to find with a small telescope in the nebula rich constellation Sagittarius. About 5,000 light-years away, the colorful study in cosmic contrasts shares this well-composed, nearly 1 degree wide field with open star cluster Messier 21 (bottom right). Trisected by dust lanes the Trifid itself is about 40 light-years across and a mere 300,000 years old. That makes it one of the youngest star forming regions in our sky, with newborn and embryonic stars embedded in its natal dust and gas clouds. Estimates of the distance to open star cluster M21 are similar to M20's, but though they share this gorgeous telescopic skyscape there is no apparent connection between the two. In fact, M21's stars are much older, about 8 million years old. via NASA https://ift.tt/2BI0maN

Comet Heart and Soul Comet Heart and Soul

The greenish coma of comet 21P/Giacobini-Zinner stands out at the left of this telephoto skyscape spanning over 10 degrees toward the northern constellations Cassiopeia and Perseus. Captured on August 17, the periodic comet is the known parent body of the upcoming Draconid meteor shower. Predicted to be at its brightest next month, the comet is actually in the foreground of the rich starfield, only about 4 light-minutes from our fair planet. Giacobini-Zinner should remain too faint for your eye to see though, like the colorful Heart and Soul nebulae near the center of the sensitive digital camera's field of view. But the pair of open star clusters at the right, h and Chi Persei, could just be seen by the unaided eye from dark locations. The Heart and Soul nebulae with their own embedded clusters of young stars a million or so years old, are each over 200 light-years across and 6 to 7 thousand light-years away. They are part of a large, active star forming complex sprawling along the Perseus spiral arm of our Milky Way Galaxy. Also known as the Double Cluster, h and Chi Persei are located at about that same distance. Periodic Giacobini-Zinner was visited by a spacecraft from Earth when the repurposed International Cometary Explorer passed through its tail in September 1985. via NASA https://ift.tt/2w5P7n1

Asteroid Ryugu from Hayabusa2 Asteroid Ryugu from Hayabusa2

This big space diamond has an estimated value of over 80 billion dollars. It's only diamond in shape, though -- asteroid 162173 Ryugu is thought to be composed of mostly nickel and iron. Asteroids like Ryugu are interesting for several reasons, perhaps foremost because they are near the Earth and might, one day in the far future, pose an impact threat. In the nearer term, Ryugu is interesting because it may be possible to send future spacecraft there to mine it, thus providing humanity with a new source of valuable metals. Scientifically, Ryugu is interesting because it carries information about how our Solar System formed billions of years ago, and why its orbit takes it so close to Earth. Japan's robotic spacecraft Hayabusa2 just arrived at this one-kilometer wide asteroid in late June. The featured image shows surface structures unknown before spacecraft Hayabusa2's arrival, including rock fields and craters. Within the next three months, Hayabusa2 is scheduled to unleash several probes, some that will land on Ryugu and hop around, while Hayabusa2 itself will mine just a little bit of the asteroid for return to Earth. via NASA https://ift.tt/2OYUFaf

Glowing Elements in the Soul Nebula Glowing Elements in the Soul Nebula

Stars are forming in the Soul of the Queen of Aethopia. More specifically, a large star forming region called the Soul Nebula (IC 1898) can be found in the direction of the constellation Cassiopeia, who Greek mythology credits as the vain wife of a King who long ago ruled lands surrounding the upper Nile river. The Soul Nebula houses several open clusters of stars, a large radio source known as W5, and huge evacuated bubbles formed by the winds of young massive stars. Located about 6,500 light years away, the Soul Nebula spans about 100 light years and is usually imaged next to its celestial neighbor the Heart Nebula (IC 1805). The featured image is a composite of three exposures in different colors: red as emitted by hydrogen gas, yellow as emitted by sulfur, and blue as emitted by oxygen. via NASA https://ift.tt/2nTX22k

Active Prominences on a Quiet Sun Active Prominences on a Quiet Sun

Why is the Sun so quiet? As the Sun enters into a period of time known as a Solar Minimum, it is, as expected, showing fewer sunspots and active regions than usual. The quietness is somewhat unsettling, though, as so far this year, most days show no sunspots at all. In contrast, from 2011 - 2015, during Solar Maximum, the Sun displayed spots just about every day. Maxima and minima occur on an 11-year cycle, with the last Solar Minimum being the most quiet in a century. Will this current Solar Minimum go even deeper? Even though the Sun's activity affects the Earth and its surroundings, no one knows for sure what the Sun will do next, and the physics behind the processes remain an active topic of research. The featured image was taken three weeks ago and shows that our Sun is busy even on a quiet day. Prominences of hot plasma, some larger than the Earth, dance continually and are most easily visible over the edge. via NASA https://ift.tt/2wgX1cN

Seeing Titan Seeing Titan

Shrouded in a thick atmosphere, Saturn's largest moon Titan really is hard to see. Small particles suspended in the upper atmosphere cause an almost impenetrable haze, strongly scattering light at visible wavelengths and hiding Titan's surface features from prying eyes. But Titan's surface is better imaged at infrared wavelengths where scattering is weaker and atmospheric absorption is reduced. Arrayed around this centered visible light image of Titan are some of the clearest global infrared views of the tantalizing moon so far. In false color, the six panels present a consistent processing of 13 years of infrared image data from the Visual and Infrared Mapping Spectrometer (VIMS) on board the Cassini spacecraft. They offer a stunning comparison with Cassini's visible light view. via NASA https://ift.tt/2Pk9ZPC

Parker vs Perseid Parker vs Perseid

The brief flash of a bright Perseid meteor streaks across the upper right in this composited series of exposures made early Sunday morning near the peak of the annual Perseid meteor shower. Set up about two miles from Space Launch Complex 37 at Cape Canaveral Air Force Station, the photographer also captured the four minute long trail of a Delta IV Heavy rocket carrying the Parker Solar Probe into the dark morning sky. Perseid meteors aren't slow. The grains of dust from periodic comet Swift-Tuttle vaporize as they plow through Earth's upper atmosphere at about 60 kilometers per second (133,000 mph). On its way to seven gravity-assist flybys of Venus over its seven year mission, the Parker Solar Probe's closest approach to the Sun will steadily decrease, finally reaching a distance of 6.1 million kilometers (3.8 million miles). That's about 1/8 the distance between Mercury and the Sun, and within the solar corona, the Sun's tenuous outer atmosphere. By then it will be traveling roughly 190 kilometers per second (430,000 mph) with respect to the Sun, a record for fastest spacecraft from planet Earth. via NASA https://ift.tt/2vMpgAH

Launch of the Parker Solar Probe Launch of the Parker Solar Probe

When is the best time to launch a probe to the Sun? The now historic answer -- which is not a joke because this really happened this past weekend -- was at night. Night, not only because NASA's Parker Solar Probe's (PSP) launch window to its planned orbit occurred, in part, at night, but also because most PSP instruments will operate in the shadow of its shield -- in effect creating its own perpetual night near the Sun. Before then, years will pass as the PSP sheds enough orbital energy to approach the Sun, swinging past Venus seven times. Eventually, the PSP is scheduled to pass dangerously close to the Sun, within 9 solar radii, the closest ever. This close, the temperature will be 1,400 degrees Celsius on the day side of the PSP's Sun shield -- hot enough to melt many forms of glass. On the night side, though, it will be near room temperature. A major goal of the PSP's mission to the Sun is to increase humanity's understanding of the Sun's explosions that impact Earth's satellites and power grids. Pictured is the night launch of the PSP aboard the United Launch Alliances' Delta IV Heavy rocket early Sunday morning. via NASA https://ift.tt/2wasUDP

M86 in the Central Virgo Cluster M86 in the Central Virgo Cluster

Is there a bridge of gas connecting these two great galaxies? Quite possibly, but it is hard to be sure. M86 on the upper left is a giant elliptical galaxy near the center of the nearby Virgo Cluster of galaxies. Our Milky Way Galaxy is falling toward the Virgo Cluster, located about 50 million light years away. To the lower right of M86 is unusual spiral galaxy NGC 4438, which, together with angular neighbor NGC 4435, are known as the Eyes Galaxies (also Arp 120). Featured here is one of the deeper images yet taken of the region, indicating that red-glowing gas surrounds M86 and seemingly connects it to NGC 4438. The image spans about the size of the full moon. It is also known, however, that cirrus gas in our own Galaxy is superposed in front of the Virgo cluster, and observations of the low speed of this gas seem more consistent with this Milky Way origin hypothesis. A definitive answer may come from future research, which may also resolve how the extended blue arms of NGC 4435 were created. via NASA https://ift.tt/2KUXHts

The Pencil Nebula in Red and Blue The Pencil Nebula in Red and Blue

This shock wave plows through interstellar space at over 500,000 kilometers per hour. Near the top and moving up in this sharply detailed color composite, thin, bright, braided filaments are actually long ripples in a cosmic sheet of glowing gas seen almost edge-on. 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 featured narrow-band, wide field image, red and blue colors track the characteristic glow of ionized hydrogen and oxygen atoms, respectively. via NASA https://ift.tt/2MlG6Ql

Moon, Mars, and Milky Way Moon, Mars, and Milky Way

Just two weeks ago, dark skies over the desert in northern Iran held this alluring celestial vista. The dramatic digital mosaic finds the Moon and Mars alongside the Milky Way's dusty rifts, stars, and nebulae. Captured through a series of exposures to cover a range in brightness, that night's otherwise Full Moon is immersed in Earth's shadow. It actually appears fainter and redder than the Red Planet itself during the widely watched total lunar eclipse. For cosmic tourists, the skyscape also includes the Lagoon (M8) and Trifid (M20) nebulae and planet Saturn shining against the Milky Way's pale starlight. The Moon isn't quite done with its shadow play, though. Today, the New Moon partially eclipses the Sun for much of northern planet Earth. via NASA https://ift.tt/2vZepm7

Spiral Galaxy NGC 6744 Spiral Galaxy NGC 6744

Beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo and appears as only a faint, extended object in small telescopes. We see the disk of the nearby island universe tilted towards our line of sight. This remarkably detailed galaxy portrait covers an area about the angular size of the full moon. In it, the giant galaxy's elongated yellowish core is dominated by the light from old, cool stars. Beyond the core, grand spiral arms are filled with young blue star clusters and speckled with pinkish star forming regions. An extended arm sweeps past a smaller satellite galaxy at the upper left. NGC 6744's galactic companion is reminiscent of the Milky Way's satellite galaxy the Large Magellanic Cloud. via NASA https://ift.tt/2OU3MJQ

Red Planet Red Moon and Mars Red Planet Red Moon and Mars

Mars is also known as The Red Planet, often seen with a reddish tinge in dark night skies. Mars shines brightly at the upper left of this gorgeous morning twilight view from Mornington Peninsula, Victoria, Australia, but the Moon and planet Earth look redder still. Taken on July 27, the totally eclipsed Moon is setting. It looks reddened because the Earth's umbral shadow isn't completely dark. Instead Earth's shadow is suffused with a faint red light from all the planet's sunsets and sunrises seen from the perspective of an eclipsed Moon. The sunsets and sunrises are reddened because Earth's atmosphere scatters blue light more strongly than red, creating the faint bluish twilight sky. Of course, craggy seaside rocks also take on the reddened colors of this Australian sunrise. via NASA https://ift.tt/2Mf7iA0

Eclipsed Moon and Mars over Mountains Eclipsed Moon and Mars over Mountains

There is something unusual about this astronomically-oriented photograph. It's not obvious -- it was discovered only during post-processing. It is not the Moon, although capturing the Moon rising during a total lunar eclipse is quite an unusually interesting sight. (Other interesting images also captured during last month's eclipse can be found here.) It is not Mars, found to the lower right of the Moon, although Mars being captured near its brightest also makes for an unusually interesting sight. (Mars is visible nearly the entire night this month; other interesting images of it can be found here.) It is not the foreground mountains, although the French Alps do provide unusually spectacular perspectives on planet Earth. (Other interesting mountainous starscapes can be found here.) It is the goat. via NASA https://ift.tt/2M0MKMw

Live: Cosmic Rays from Minnesota Live: Cosmic Rays from Minnesota

Cosmic rays from outer space go through your body every second. Typically, they do you no harm. The featured image shows some of these fast moving particles as streaks going through Fermilab's NOvA Far Detector located in Ash River, Minnesota, USA. Although the image updates every 15 seconds, it only shows cosmic rays that occurred over a (changing) small fraction of that time, and mostly shows only one type of particle: muons. The NOvA Far Detector's main purpose is not to detect cosmic rays, though, but rather neutrinos from the NuMI beam shot through the Earth from Fermilab near Chicago, Illinois, USA, 810 kilometers away. Only a few neutrino events are expected in NOvA per week, though. The NuMI / NOvA experiment is allowing humanity to better explore the nature of neutrinos, for example how frequently they change type during their trip. Cosmic rays themselves were discovered only about 100 years ago and can not only alter computer memory, but may have helped to create DNA mutations that resulted in, eventually, humans. via NASA https://ift.tt/2vnfeFR

Trapezium: At the Heart of Orion Trapezium: At the Heart of Orion

Near the center of this sharp cosmic portrait, at the heart of the Orion Nebula, are four hot, massive stars known as the Trapezium. Gathered within a region about 1.5 light-years in radius, they dominate the core of the dense Orion Nebula Star Cluster. Ultraviolet ionizing radiation from the Trapezium stars, mostly from the brightest star Theta-1 Orionis C powers the complex star forming region's entire visible glow. About three million years old, the Orion Nebula Cluster was even more compact in its younger years and a recent dynamical study indicates that runaway stellar collisions at an earlier age may have formed a black hole with more than 100 times the mass of the Sun. The presence of a black hole within the cluster could explain the observed high velocities of the Trapezium stars. The Orion Nebula's distance of some 1,500 light-years would make it the closest known black hole to planet Earth. via NASA https://ift.tt/2vgjN4y

Central Lunar Eclipse Central Lunar Eclipse

Reddened by scattered sunlight, the Moon in the center is passing through the center of Earth's dark umbral shadow in this July 27 lunar eclipse sequence. Left to right the three images are from the start, maximum, and end to 103 minutes of totality from the longest lunar eclipse of the 21st century. The longest path the Moon can follow through Earth's shadow does cross the shadow's center, that's what makes such central lunar eclipses long ones. But July 27 was also the date of lunar apogee, and at the most distant part of its elliptical orbit the Moon moves slowest. For the previous lunar eclipse, last January 31, the Moon was near its orbital perigee. Passing just south of the Earth shadow central axis, totality lasted only 76 minutes. Coming up on January 21, 2019, a third consecutive total lunar eclipse will also be off center and find the Moon near perigee. Then totality will be a mere 62 minutes long. via NASA https://ift.tt/2AClkXW

Eclipse over the Gulf of Poets Eclipse over the Gulf of Poets

The total phase of the July 27 lunar eclipse lasted for an impressive 103 minutes. That makes it the longest total lunar eclipse of the 21st century. The Moon passed through the center of Earth's shadow while the Moon was near apogee, the most distant point in its elliptical orbit. From start to finish, the entire duration of totality is covered in this composite view. A dreamlike scene, it includes a sequence of digital camera exposures made every three minutes. The exposures track the totally eclipsed lunar disk, accompanied on that night by bright planet Mars, as it climbs above the seaside village of Tellaro, Italy. In the foreground lies the calm mediteranean Gulf of La Spezia, known to some as the Gulf of Poets. In the 3rd century BCE, heliocentric astronomer Aristarchus also tracked the duration of lunar eclipses, though without the benefit of digital clocks and cameras. Using geometry he devised a way to calculate the Moon's distance from the eclipse duration, in terms of the radius of planet Earth. via NASA https://ift.tt/2LTwGLC