Saturday, April 9, 2016

New Horizons Did Amazing Work Before Even Arriving At Pluto

New Horizons Did Amazing Work Before Even Arriving At Pluto:



The solar wind data collected by New Horizons will help create more accurate models of the space environment in our Solar System. Image: NASA's Goddard Space Flight Center Scientific Visualization Studio, the Space Weather Research Center (SWRC) and the Community-Coordinated Modeling Center (CCMC), Enlil and Dusan Odstrcil (GMU)


Anybody with an ounce of intellectual curiosity (and an internet connection) has seen the images of Pluto and its system taken by the New Horizons probe. The images and data from New Horizons have opened the door to Pluto's atmosphere, geology, and composition. But New Horizons wasn't entirely dormant during its 9 year, billion-plus mile journey to Pluto.New Horizons returned 3 years worth of data on the solar wind that sweeps through the near-emptiness of space. The solar wind is the stream of particles that is released from the upper atmosphere of the Sun, called the corona. The Sun's solar wind is what creates space weather in our solar system, and the wind itself varies in temperature, speed, and density.The solar wind data from New Horizons, which NASA calls an "unprecedented set of observations," is filling in a gap in our knowledge. Observatories like the Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO) are studying the Sun up close, and the Voyager probes have sampled the solar wind near the edge of the heliosphere, where the solar wind meets interstellar space, but New Horizons is giving us our first look at the solar wind in Pluto's region of space.

pluto-space-wx-sim
This solar wind data should shed some light on a number of things, including the dangerous radiation astronauts face when in space. There is a type of particle with extreme energy levels called anomalous cosmic rays. When travelling close to Earth, these high-velocity rays can be a serious radiation hazard to astronauts.The data from New Horizons reveals particles that pick up an acceleration boost, which makes them exceed their initial speed. It's thought that these particles could be the precursors to anomalous cosmic rays. A better understanding of this might lead to a better way to protect astronauts.These same rays have other effects further out in space. It looks like they are partly responsible for shaping the edge of the heliosphere; the region in space where the solar wind meets the interstellar medium.New Horizons has also told us something about the structure of the solar wind the further it travels from the Sun. Close to the Sun, phenomena like coronal mass ejections (CMEs) have a clearly discernible structure. And the differences in the solar wind, in terms of velocity, density, and temperature, are also discernible. They're determined by the region of the Sun they came from. New Horizons found that far out in the solar system, these structures have changed."At this distance, the scale size of discernible structures increases, since smaller structures are worn down or merge together," said Heather Elliott, a space scientist at the Southwest Research Institute in San Antonio, Texas, and the lead author of a paper to be published in the Astrophysical Journal. "It’s hard to predict if the interaction between smaller structures will create a bigger structure, or if they will flatten out completely."The Voyager probes measured the solar wind as they travelled through our Solar System into the interstellar medium. They've told us a lot about the solar wind in the more distant parts of our system, but their instruments aren't as sensitive and advanced as New Horizons'. This second data set from New Horizons is helping to fill in the blanks in our knowledge.

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Venus Compared to Earth

Venus Compared to Earth:



Earth and Venus. Image credit: NASA


Venus is often referred to as "Earth's Twin" (or "sister planet"), and for good reason. Despite some rather glaring differences, not the least of which is their vastly different atmospheres, there are enough similarities between Earth and Venus that many scientists consider the two to be closely related. In short, they are believed to have been very similar early in their existence, but then evolved in different directions.Earth and Venus are both terrestrial planets that are located within the Sun's Habitable Zone (aka. "Goldilocks Zone") and have similar sizes and compositions. Beyond that, however, they have little in common. Let's go over all their characteristics, one by one, so we can in what ways they are  different and what ways they are similar.

Size, Mass and Orbit:

In terms of their respective sizes, masses and compositions, Venus and Earth are quite similar. Whereas Earth has a mean radius of 6,371 km and a mass 5,972,370,000 quadrillion kg, Venus has a mean radius of about 6,052 km and a mass of 4,867,500,000 quadrillion kg. This means that Venus is roughly 0.9499 the size of Earth and 0.815 as massive. In terms of volume, the two planets are almost neck and neck, with Venus possessing 0.866 as much volume as Earth (928.45 billion cubic km compared to Earth's 1083.21 billion). https://youtu.be/euhLuWNEi0gBut when it comes to orbit, the two planets are a bit different. Earth orbits the Sun at an average distance (semi-major axis) of 149,598,023 km (92,955,902 mi), ranging from 147,095,000 km (91,401,000 mi) at perihelion to 152,100,000 km (94,500,000 mi) at aphelion. Venus, meanwhile, orbits the Sun at an average distance of 108,208,000 km, ranging from 107,477,000 km at perihelion to 108,939,000 km. Basically, Venus orbits closer to our Sun and with an eccentricity that is less than one-third that of Earth's (0.006772 compared to 0.0167086). In addition, Earth's axis is tilted far more than Venus' towards the Solar ecliptic - 23.5° compared to Venus' 2.64°. This greater proximity to the Sun is largely responsible for Venus' runaway greenhouse effect, and the low eccentricity (combined with the minor tilt in its axis) results in very little variation in temperature (see below).

Structure and Composition:

Being terrestrial planets, Venus and Earth have similar structures and compositions. Earth's interior is divided into layers based on their chemical or physical properties, consisting of a core, mantle, and outer crust. Whereas the core region consists of nickel and iron, the mantle and outer crust are composed of silicate rock and minerals.While little direct information exists about Venus' seismology, its similarity in size and density to Earth suggests that it has a similar internal structure - consisting of a core, mantle and crust. Like that of Earth, the Venusian core is at least partially liquid because the two planets have been cooling at about the same rate.The principal difference between the two planets is the lack of evidence for plate tectonics on Venus, possibly because its crust is too strong to subduct without water to make it less viscous. This results in reduced heat loss from the planet, preventing it from cooling.Another major difference is that Earth's core is divided between an inner and outer core. Whereas the outer core is believed to consist of a low viscosity liquid, the inner core is believed to be solid. The liquid outer core also rotates in the opposite direction as the planet, producing a dynamo effect that is believed to be the source of Earth's magnetosphere (see below).

Surface Features:

Unlike other planet’s in our Solar System, the majority of Earth’s surface is covered in liquid water. In fact, about 70.8% of the surface is covered by oceans, lakes, rivers and other sources, with much of the continental shelf below sea level. In addition, Earth’s terrain varies greatly from place to place, regardless of whether or not it is above or below sea level.The submerged surface has mountainous features, as well as undersea volcanoes, oceanic trenches, submarine canyons, oceanic plateaus and abyssal plains. The remaining portions of the surface are covered by mountains, deserts, plains, plateaus, and other landforms. Over long periods, the surface undergoes reshaping due to a combination of tectonic activity and erosion.https://youtu.be/n-kg0GbQkEkVenus' surface, in contrast, has little variation in terms of elevation, with the majority covered by smooth, volcanic plains. In fact, it is estimated that if a terraforming event began to allow for water to accumulate on the surface, roughly 80% of the planet would be below sea level. The majority of the above ground landmass would be in the form of two that formed from the planet's two main highland regions -  Ishtar Terra, located in the northern hemisphere, and Aphrodite Terra, just south of the equator.Venus surface appears to have been shaped by volcanic activity rather than tectonic activity. Though Venus is not more volcanic ally active than Earth, its older crust means that it has several times as many volcanoes as Earth, with 167 measuring over 100 km across. Whereas Earth's oceanic crust is continually recycled by subduction at the boundaries of tectonic plates, and has an average age of about 100 million years, Venus' surface is estimated to be 300–600 million years old.

Atmosphere and Temperature:

Earth’s atmosphere is made up of five main layers – the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere. As a rule, air pressure and density decrease the higher one goes into the atmosphere and the farther one is from the surface. However, the relationship between temperature and altitude is more complicated, and may even rise with altitude in some cases.Earth's temperature is also subject to variation depending on the time of day, time of year, and where on the planet the temperature is being measured from. Temperatures variations are the result of changes in Earth's orbit, rotation, and its tilted axis. The average temperature is 14° C, with the hottest recorded temperature being 70.7°C (159°F) in the Lut Desert of Iran and the coldest being -89.2°C (-129°F) at Vostok Station in Antarctica.https://youtu.be/96C1eCaTtvg

Meanwhile, Venus’ surface temperature experiences little to no variation, owing to its dense atmosphere, very slow rotation, and very minor axial tilt. Its mean surface temperature of 735 K (462 °C/863.6 °F) is virtually constant, with little or no change between day and night, at the equator or the poles. The one exception is the highest point on Venus, Maxwell Montes, where atmospheric pressure drops to about 4.5 MPa (45 bar) and the temperature drops to about 655 K (380 °C).

Magnetic Fields:

It is a well known fact that Earth's strong magnetic field is intrinsic to it being able to support life. The main part of this field is generated in the core, the site of a dynamo process that converts the kinetic energy of convective fluid motion into electrical and magnetic field energy. The convection movements in the core are chaotic, causing the magnetic poles to drift and periodically change alignment. This causes field reversals at irregular intervals averaging a few times every million years, the most recent of which occurred approximately 700,000 years ago.The field extends outwards from the core, through the mantle, and up to Earth's surface, where it form a dipole (the poles of which are located close to Earth's geographic poles). At the equator of the magnetic field, the magnetic-field strength at the surface is 3.05 × 10?5 Teslas, with global magnetic dipole moment of 7.91 × 1015 T m3. Ions and electrons of the solar wind, and cosmic rays that would otherwise strip away Earth's atmosphere, are deflected by this magnetosphere.https://youtu.be/BOA_yKsaYwMDuring a magnetic storm, charged particles can be deflected from the outer magnetosphere, directed along field lines into Earth's ionosphere, where atmospheric atoms can be excited and ionized, causing the phenomena known as Aurora Borealis and Aurora Australis.Venus also has a magnetic field, though it is significantly weaker than Earth's. What's more, Venus' magnetic field is induced by an interaction between the ionosphere and the solar wind rather than by an internal dynamo in the core like the one inside Earth. Venus's small induced magnetosphere provides negligible protection to the atmosphere against cosmic radiation.

This implies that Venus is missing a dynamo, most likely because of a lack of convection in its core. This may have been a result of a global resurfacing event that shut down plate tectonics and led to a reduced heat flux through the crust. This caused the mantle temperature to increase, thereby reducing the heat flux out of the core.

Conclusions:

So let's review. Earth and Venus have their share of similarities, but also some rather stark differences. Let's compare them, category by category, placing Earth's values on the left and Venus' on the right.Mean Radius:                6,371.0 km                   6,051.8 ± 1.0 km    Mass:                                5.972 37 x 1024 kg       4.8675 x 1024 kgVolume:                           10.8321×1011 km3       9.2843×1011 km3Semi-Major Axis:         149,598,023 km          108,208,000 kmAir Pressure:                 101.325 kPa                   9200 kPa Gravity:                            9.8 m/s²                        8.87 m/s2Avg. Temperature:      14°C (57.2 °F)               462 °C (863.6 °F)Temp. Variations:      ±160 °C (278°F)            640 C ()Axial Tilt:                         23.5°                               2.64°Length of Day:               24 hours                        117 days Length of Year:             365 days                       224.7 days Rotation:                         Prograde                       Retrograde Water:                              Yes                                  No Polar Ice Caps:               Yes                                 NoAs you can see, things are run the gambit from being very close, to very different. If people are to call Venus home someday, we'll have to do some serious renovating to bring the planet up to code!We have written many interesting articles about Venus here at Universe Today. Here's The Planet Venus, Interesting Facts About Venus, What Is The Average Surface Temperature On Venus?  Colonizing Venus With Floating Cities and How Do We Terraforming Venus?For more information, check out the Hubblesite's News Releases about Venus, and here's NASA's Solar System Exploration Guide to Venus.Astronomy Cast also has an interesting episode about the planet Venus. Listen to it here, Episode 50: Venus.

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Supermassive Black Hole Found In The Cosmic Boonies

Supermassive Black Hole Found In The Cosmic Boonies:



A supermassive black hole has been found in an unusual spot: an isolated region of space where only small, dim galaxies reside. Image credit: NASA/JPL-Caltech


Astronomers have found a massive black hole in a place they never expected to find one. The hole comes in at 17 billion solar masses, which makes it the second largest ever found. (The largest is 21 billion solar masses.) And though its enormous mass is noteworthy, its location is even more intriguing.Supermassive black holes are typically found at the centers of huge galaxies. Most galaxies have them, including our own Milky Way galaxy, where a comparatively puny 4 million solar mass black hole is located. Not only that, these gargantuan holes tend to be located in galaxies that are part of a large cluster of galaxies. Being surrounded by all that mass is a prerequisite for the formation of supermassive black holes. The largest one known, at 21 billion solar masses, is located in a very dense region of space called the Coma Cluster, where over 1,000 galaxies have been identified.The largest supermassive holes also tend to be surrounded by bright companions, who have also grown large from the plentiful mass in their surroundings. (Of course, its not the black holes that are bright, but the quasars that surround them.) The long and the short of it is that supermassive black holes are usually found in galaxy clusters, and usually have other supermassive companions in the same region of space. They're not found in isolation.But this newly found black hole is in a rather sparse region of space. It's in NGC 1600, an elliptical galaxy in the constellation Eridanus, 200 million light years from Earth. NGC 1600 is not a particularly large galaxy, and though it has been considered part of a larger group of galaxies, all its companions are much dimmer in comparison. So NGC 1600 is a rather small, isolated galaxy, with only a few dim companions.There's another way that supermassive holes can form. Instead of growing large over time, by feeding on the mass of their home galaxies and galaxy clusters, they can form when two galaxies merge, and two smaller holes become one. But even this requires that they be in a region where galaxies are plentiful, allowing for more collisions and mergers.It may be possible that NGC is the result of a merger of two galaxies, or that it is two black holes that are currently merging. Or it could be that NGC 1600's region of space was once extremely rich in gas, in the early days of the Universe, and that's what gave rise to this 'out of place' supermassive black hole.There is much to be learned about the conditions that give rise to these behemoth black holes. The MASSIVE study will combine several telescopes to survey and catalogue the largest galaxies and black holes. This should tell astronomers a lot about their distribution, and about the circumstances that allow them to exist. We might find even larger ones.

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A Star With A Disk Of Water Ice? Meet HD 100546

A Star With A Disk Of Water Ice? Meet HD 100546:



Young stars have a disk of gas and dust around them called a protoplanetary disk. Out of this disk planets are formed, and the presence of water ice in the disc affects where different types of planets form. Credit: NASA/JPL-Caltech


It might seem incongruous to find water ice in the disk of gas and dust surrounding a star. Fire and ice just don't mix. We would never find ice near our Sun.But our Sun is old. About 5 billion years old, with about 5 billion more to go. Some younger stars, of a type called Herbig Ae/Be stars (after American astronomer George Herbig,) are so young that they are surrounded by a circumstellar disk of gas and dust which hasn't been used up by the formation of planets yet. For these types of stars, the presence of water ice is not necessarily unexpected.Water ice plays an important role in a young solar system. Astronomers think that water ice helps large, gaseous, planets to form. The presence of ice makes the outer section of a planetary disk more dense. This increased density allows the cores of gas planets to coalesce and form.Young solar systems have what is called a snowline. It is the boundary between terrestrial and gaseous planets. Beyond this snowline, ice in the protoplanetary disk encourages gas planets to form. Inside this snowline, the lack of water ice contributes to the formation of terrestrial planets. You can see this in our own Solar System, where the snowline must have been between Mars and Jupiter.A team of astronomers using the Gemini telescope observed the presence of water ice in the protoplanetary disk surrounding the star HD 100546, a Herbig Ae/Be star about 320 light years from us. At only 10 million years old, this star is rather young, and it is a well-studied star. The Hubble has found complex, spiral patterns in the disk, and so far these patterns are unexplained.HD 100546 is also notable because in 2013, research showed the probable ongoing formation of a planet in its disk. This presented a rare opportunity to study the early stages of planet formation. Finding ice in the disk, and discovering how deep it exists in the disk, is a key piece of information in understanding planet formation in young solar systems.Finding this ice took some clever astro-sleuthing. The Gemini telescope was used, with its Near-Infrared Coronagraphic Imager (NICI), a tool used to study gas giants. The team installed H2O ice filters to help zero in on the presence of water ice. The protoplanetary disk around young stars, as in the case of HD 100546, is a mixed up combination of dusts and gases, and isolating types of materials in the disk is not easy.Water ice has been found in disks around other Herbig Ae/Be stars, but the depth of distribution of that ice has not been easy to understand. This paper shows that the ice is present in the disk, but only shallowly, with UV photo desorption processes responsible for destroying water ice grains closer to the star.It may seem trite so say that more study is needed, as the authors of the study say. But really, in science, isn't more study always needed? Will we ever reach the end of understanding? Certainly not. And certainly not when it comes to the formation of planets, which is a pretty important thing to understand.

The post A Star With A Disk Of Water Ice? Meet HD 100546 appeared first on Universe Today.

NGC 6357: Cathedral to Massive Stars

NGC 6357: Cathedral to Massive Stars:

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2016 March 27


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NGC 6357: Cathedral to Massive Stars

Image Credit: NASA, ESA and Jesús Maíz Apellániz (IAA, Spain); Acknowledgement: Davide De Martin (ESA/Hubble)


Explanation: How massive can a normal star be? Estimates made from distance, brightness and standard solar models had given one star in the open cluster Pismis 24 over 200 times the mass of our Sun, making it one of the most massive stars known. This star is the brightest object located just above the gas front in the featured image. Close inspection of images taken with the Hubble Space Telescope, however, have shown that Pismis 24-1 derives its brilliant luminosity not from a single star but from three at least. Component stars would still remain near 100 solar masses, making them among the more massive stars currently on record. Toward the bottom of the image, stars are still forming in the associated emission nebula NGC 6357. Appearing perhaps like a Gothic cathedral, energetic stars near the center appear to be breaking out and illuminating a spectacular cocoon.

Tomorrow's picture: Orion Mountain



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Orions Belt and Sword over Teides Peak

Orions Belt and Sword over Teides Peak:

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2016 March 28


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Orion's Belt and Sword over Teide's Peak

Image Credit & Copyright: Cesar & Carlos Tejedor


Explanation: The southern part of Orion, the famous constellation and mythical hunter, appears quite picturesque posing here over a famous volcano. Located in the Canary Islands off the northwest coast of Africa, the snow-peaked Teide is one of the largest volcanoes on Earth. Lights from a group planning to summit Teide before dawn are visible below the volcano's peak. In this composite of exposures taken from the same location one night last month, the three iconic belt stars of Orion are seen just above the peak, while the famous Orion Nebula and the rest of Orion's sword are visible beyond the volcano's left slope. Also visible in the long duration sky image are the Horsehead Nebula, seen as a dark indentation on the red emission nebula to the belt's left, and the Flame Nebula, evident just above and to the right of the Horsehead.

Tomorrow's picture: rover, dune, mountain, mars



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NGC 6188 and NGC 6164

NGC 6188 and NGC 6164:

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2016 March 30


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NGC 6188 and NGC 6164

Image Credit & Copyright: Martin Pugh & Rick Stevenson


Explanation: Fantastic shapes lurk in clouds of glowing gas in the giant star forming region NGC 6188. The emission nebula is found about 4,000 light years away near the edge of a large molecular cloud unseen at visible wavelengths, in the southern constellation Ara. Massive, young stars of the embedded Ara OB1 association were formed in that region only a few million years ago, sculpting the dark shapes and powering the nebular glow with stellar winds and intense ultraviolet radiation. The recent star formation itself was likely triggered by winds and supernova explosions, from previous generations of massive stars, that swept up and compressed the molecular gas. Joining NGC 6188 on this cosmic canvas, visible toward the lower right, is rare emission nebula NGC 6164, also created by one of the region's massive O-type stars. Similar in appearance to many planetary nebulae, NGC 6164's striking, symmetric gaseous shroud and faint halo surround its bright central star near the bottom edge. The impressively wide field of view spans over 3 degrees (six full Moons), corresponding to over 200 light years at the estimated distance of NGC 6188. Three image sets have been included in the featured composite.

Tomorrow's picture: north and south



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Big Dipper to Southern Cross

Big Dipper to Southern Cross:

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2016 March 31


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Explanation: Welcome to an equatorial night. This remarkable 24 frame night skyscape was captured from Maba Beach on the Indonesian island of Halmahera during the evening of March 4. Seen from a mere 0.7 degrees northern latitude, both famous northern and southern asterisms and navigational aids lie within the panoramic view. The Big Dipper is on the far left and Southern Cross at the far right. Beyond the fading campfire on that night a yellow-orange celestial triangle is set by Mars, Antares, and Saturn. It stands above the rising central Milky Way, or "Miett" in the local Maba language. Of course, you can follow the pole pointing stars in the cup of the Big Dipper or body of the Southern Cross to the north and south celestial poles. Both lie just at the horizon in the view from the island's equatorial beach.

Europa: Discover Life Under the Ice

Europa: Discover Life Under the Ice:

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2016 April 1


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Explanation: Looking for an interplanetary vacation destination? Consider a visit to Europa, one of the Solar System's most tantalizing moons. Ice-covered Europa follows an elliptical path in its 85 hour orbit around our ruling gas giant Jupiter. Heat generated from strong tidal flexing by Jupiter's gravity keeps Europa's salty subsurface ocean liquid all year round. That also means even in the absence of sunlight Europa has energy that could support simple life forms. Unfortunately, it is currently not possible to make reservations at restaurants on Europa, where you might enjoy a dish of the local extreme shrimp. But you can always choose another destination from Visions of the Future.

Close up of the Bubble Nebula

Close up of the Bubble Nebula:

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2016 April 3


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Close-up of the Bubble Nebula

Image Credit: NASA, ESA, Hubble Legacy Archive; Processing & License: Judy Schmidt


Explanation: It's the bubble versus the cloud. NGC 7635, the Bubble Nebula, is being pushed out by the stellar wind of massive central star BD+602522. Next door, though, lives a giant molecular cloud, visible to the right. At this place in space, an irresistible force meets an immovable object in an interesting way. The cloud is able to contain the expansion of the bubble gas, but gets blasted by the hot radiation from the bubble's central star. The radiation heats up dense regions of the molecular cloud causing it to glow. The Bubble Nebula, featured here in scientifically mapped colors to bring up contrast, is about 10 light-years across and part of a much larger complex of stars and shells. The Bubble Nebula can be seen with a small telescope towards the constellation of the Queen of Aethiopia (Cassiopeia).

Astrophysicists: Browse 1,200+ codes in the Astrophysics Source Code Library

Tomorrow's picture: Seljarlandsfossian Rhapsody



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Lucid Dreaming

Lucid Dreaming:

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2016 April 4


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Lucid Dreaming

Image Credit & Copyright: Arnar Kristjansson; Rollover Annotation: Judy Schmidt


Explanation: Is this the real world? Or is it just fantasy? The truth started with a dream -- a dream that the spectacular Seljarlandsfoss waterfall in southern Iceland could be photographed with a backdrop of an aurora-filled sky. Soon after a promising space weather report, the visionary astrophotographer and his partner sprang into action. After arriving, capturing an image of the background sky, complete with a cool green aurora, turned out to be the easy part. The hard part was capturing the waterfall itself, for one reason because mist kept fogging the lens! Easy come, easy go -- it took about 100 times where someone had to go back to the camera -- on a cold night and over slippery rocks -- to see how the last exposure turned out, wipe the lens, and reset the camera for the next try. Later, the best images of land and sky were digitally combined. Visible in the sky, even well behind the aurora, are numerous stars of the northern sky. The resulting title -- given by the astrophotographer -- was influenced by a dream-like quality of the resulting image, possibly combined with the knowledge that some things really mattered in this effort to make a dream come true.

Tomorrow's picture: lava world



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Auroras and the Magnetosphere of Jupiter

Auroras and the Magnetosphere of Jupiter:

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2016 April 6


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Auroras and the Magnetosphere of Jupiter

Illustration Credit: JAXA; Inset Image Credit: NASA, ESA, Chandra, Hubble


Explanation: Jupiter has auroras. Like near the Earth, the magnetic field of our Solar System's largest planet compresses when impacted by a gust of charged particles from the Sun. This magnetic compression funnels charged particles towards Jupiter's poles and down into the atmosphere. There, electrons are temporarily excited or knocked away from atmospheric gases, after which, when de-exciting or recombining with atmospheric ions, auroral light is emitted. The featured illustration portrays the magnificent magnetosphere around Jupiter in action. In the inset image released last month, the Earth-orbiting Chandra X-ray Observatory shows unexpectedly powerful X-ray light emitted by Jovian auroras, depicted in false-colored purple. That Chandra inset is superposed over an optical image taken at a different time by the Hubble Space Telescope. This aurora on Jupiter was seen in October 2011, several days after the Sun emitted a powerful Coronal Mass Ejection (CME).

Tomorrow's picture: star hub



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Wolf-Lundmark-Melotte

Wolf-Lundmark-Melotte:

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2016 April 7


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Wolf-Lundmark-Melotte

Image Credit: ESO, VST/Omegacam Local Group Survey

Explanation: Named for the three astronomers instrumental in its discovery and identification, Wolf - Lundmark - Melotte (WLM) is a lonely dwarf galaxy. Seen toward the mostly southern constellation Cetus, about 3 million light-years from the Milky Way, it is one of the most remote members of our local galaxy group. In fact, it may never have interacted with any other local group galaxy. Still, telltale pinkish star forming regions and hot, young, bluish stars speckle the isolated island universe. Older, cool yellowish stars fade into the small galaxy's halo, extending about 8,000 light-years across. This sharp portrait of WLM was captured by the 268-megapixel OmegaCAM widefield imager and survey telescope at ESO's Paranal Observatory.

Tomorrow's picture: Lapland at Night



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Lapland Northern Lights

Lapland Northern Lights:

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2016 April 8


See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: Early spring in the northern hemisphere is good season for aurora hunters. Near an equinox Earth's magnetic field is oriented to favor interactions with the solar wind that trigger the alluring glow of the northern lights. On March 28/29 the skies over Kaunispää Hill, Lapland, Finland did not disappoint. That night's expansive auroral curtains are captured in this striking panoramic view that covers a full 360 degrees. Local skywatchers were mesmerized by bright displays lasted throughout the dark hours, shimmering with colors easily visible to the naked eye.

Wednesday, April 6, 2016

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