Total Solar Eclipse Shadow from a Balloon - Astronomy picture of the day - 2018 August 27

Total Solar Eclipse Shadow from a Balloon 
Image Credit: Kuaray Project, NASA Eclipse Ballooning Project, Brasilia Astronomy Club, Montana State U.

Explanation: 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 crossingthe 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.

Fire on Earth - Astronomy picture of the day - 2018 August 26

Fire on Earth 
Image Credit: John McColgan (AFS, BLM)

Explanation: 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 orlightning 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.

Tchaikovsky - "Immagini autunnali" - Slides - Musica

"Immagini autunnali"

Stripping ESO 137-001 - Astronomy picture of the day - 2018 August 25

Stripping ESO 137-001 
Image Credit: NASA, ESA, CXC

Explanation: 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.

Messier 20 and 21 - Astronomy picture of the day - 2018 August 24

Messier 20 and 21 
Image Credit & Copyright: Ignacio Diaz Bobillo

Explanation: 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.

Comet, Heart and Soul - Astronomy picture of the day - 2018 August 23

Comet, Heart and Soul
Image Credit & Copyright: Juan Carlos Casado (TWAN, Earth and Stars)

Explanation: 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.

Asteroid Ryugu from Hayabusa2 - Astronomy picture of the day - 2018 August 22

Asteroid Ryugu from Hayabusa2 
Image Credit & Copyright: ISAS, JAXA,

Explanation: 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 closeto 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.

Glowing Elements in the Soul Nebula - Astronomy picture of the day - 2018 August 21

Glowing Elements in the Soul Nebula 
Image Credit & Copyright: Jesús M.Vargas & Maritxu Poyal

Explanation: 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.

Active Prominences on a Quiet Sun - Astronomy picture of the day - 2018 August 20

Active Prominences on a Quiet Sun  Image Credit & Copyright: Alan Friedman (Averted Imagination)

Explanation: 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.

Asperitas Clouds Over New Zealand - Astronomy picture of the day - 2018 August 19

Asperitas Clouds Over New Zealand 
Image Credit & Copyright: Witta Priester

Explanation: What kind of clouds are these? Although their cause is presently unknown, such unusual atmospheric structures, as menacing as they might seem, do not appear to be harbingers of meteorological doom. Formally recognized as a distinct cloud type only last year, Asperitas clouds can be stunning in appearance, unusual in occurrence, and are relatively unstudied. Whereas most low cloud decks are flat bottomed, asperitas clouds appear to have significant vertical structure underneath. Speculation therefore holds that asperitas clouds might be related to lenticular clouds that form near mountains, or mammatus clouds associated with thunderstorms, or perhaps a foehn wind -- a type of dry downward wind that flows off mountains. Such a wind called the Canterbury arch streams toward the east coast of New Zealand's South Island. The featured image, taken above Hanmer Springs in Canterbury, New Zealand, in 2005, shows great detail partly because sunlight illuminates the undulating clouds from the side.