Explanation: What are those streaks of light in the sky? First and foremost, the arching structure is the central band of our Milky Way galaxy. Visible in this galactic band are millions of distant stars mixed with numerous lanes of dark dust. Harder to discern is a nearly vertical beam of light rising from the horizon, just to the right of the image center. This beam is zodiacal light, sunlight scattered by dust in our Solar System that may be surprisingly prominent just after sunset or just before sunrise. In the foreground are several telescopes of the Bosque Alegre Astrophysical Station of the National University of Cordoba in Argentina. The station schedules weekend tours and conducts research into the nature of many astronomical objects including comets, active galaxies, and clusters of galaxies. The featured image was taken early this month.
Dear Geckzilla. Would love your definition of sneaky. Mercury is much maligned. After all one just has to be quick to bask in its brilliance
Sneaky as in stealthy. It's just between the horizon and the clouds and will easily vanish silently. When I was annotating I almost missed it, figuring it for some kind of terrestrial source.
Just call me "geck" because "zilla" is like a last name.
Dear Geckzilla. Would love your definition of sneaky. Mercury is much maligned.
After all one just has to be quick to bask in its brilliance
Sneaky as in stealthy. It's just between the horizon and the clouds and will easily vanish silently.
When I was annotating I almost missed it, figuring it for some kind of terrestrial source.
The APOD forgot to credit Judy Schmidt for providing the rollover annotation. (My bad.) A great job again by Judy and the APOD has been updated to credit her. - RJN
Great photo! The rather strange structure in the middle is a telescope built at the Munnerlyn Astronomical Laboratory here at Texas A&M University. It was built by Ryan Oelkers, and is a remotely operated telescope controlled here at A&M to survey nearby young stellar regions for exoplanets and binaries.
nsuntzeff wrote:Great photo! The rather strange structure in the middle is a telescope built at the Munnerlyn Astronomical Laboratory here at Texas A&M University. It was built by Ryan Oelkers, and is a remotely operated telescope controlled here at A&M to survey nearby young stellar regions for exoplanets and binaries.
Thanks for that. I was wondering what it was! There's not much information at the observatory's website about their various instruments.
Just call me "geck" because "zilla" is like a last name.
Why do cats sleep on surprisingly prominent objects? Maybe they get tired of us snoring. Now I know what C-PAP is. Cat – Positional Animal Pressure.
It's a very picturesque image with much to show and admire from the southern night sky. I am curious how astrophotograhers deal with bright clouds in the sky though. If one intensifies the Milky Way - to see it better - it appears the clouds are behind the stars. It's quite a balancing act.
I wonder. Would the Zodiacal light appear brighter or dimmer when viewed in the asteroid belt. Do we have any pictures by the Dawn spacecraft orbiting Ceres (or before when it orbited Vesta) where the Sun is just below the horizon? Would it be dimmer because it is farther from the source? Might it be brighter because there were more objects sharing the orbit with the asteroids? I wonder.
Craig Willford wrote:
Would the Zodiacal light appear brighter or dimmer when viewed in the asteroid belt. Do we have any pictures by the Dawn spacecraft orbiting Ceres (or before when it orbited Vesta) where the Sun is just below the horizon? Would it be dimmer because it is farther from the source? Might it be brighter because there were more objects sharing the orbit with the asteroids? I wonder.
Zodiacal light would appear dimmer when viewed in the asteroid belt because there are much fewer (though somewhat larger) dust particles:
https://en.wikipedia.org/wiki/Zodiacal_light wrote:
<<Zodiacal light is a faint, roughly triangular, diffuse white glow seen in the night sky that appears to extend up from the vicinity of the Sun along the ecliptic or zodiac. The zodiacal light decreases in intensity with distance from the Sun, but on very dark nights it has been observed in a band completely around the ecliptic. In fact, the zodiacal light covers the entire sky, being responsible in large part for the total skylight on a moonless night. The dust forms a thick pancake-shaped cloud in the Solar System collectively known as the zodiacal cloud, which occupies the same plane as the ecliptic. The [zodiacal] dust particles are between 10 and 300 micrometres in diameter, most with mass around 150 micrograms.
The source of the dust has been long debated. Until recently, it was thought that the dust originated from the tails of active comets and from collisions between asteroids in the asteroid belt. Peter Jenniskens had previously recognized that many of our meteor showers have no known active comet parent bodies. In a 2010 article in the Astrophysical Journal, David Nesvorny and Peter Jenniskens attributed over 85 percent of the dust to occasional fragmentations of Jupiter-family comets that are nearly dormant. Jupiter-family comets have orbital periods of less than 20 years and are considered dormant when not actively outgassing, but may do so in the future. Nesvorny and Jenniskens' first fully dynamical model of the zodiacal cloud demonstrated that only if the dust was released in orbits that approach Jupiter, is it stirred up enough to explain the thickness of the zodiacal dust cloud. The dust in meteoroid streams is much larger, 300 to 10,000 micrometres in diameter, and falls apart in smaller zodiacal dust grains over time. In 2015, new results published in the magazine "Nature" using the secondary ion dust spectrometer COSIMA on board the ESA/Rosetta orbiter confirmed that the parent bodies of interplanetary dust are most probably Jupiter-family comets such as comet 67P/Churyumov-Gerasimenko.
The Poynting–Robertson effect forces the dust into more circular (but still elongated) orbits, while spiralling slowly into the Sun. Hence a continuous source of new particles is needed to maintain the zodiacal cloud.
Particles can be reduced in size by collisions or by space weathering. When ground down to sizes less than 10 micrometres, the grains are removed from the inner Solar System by solar radiation pressure. The dust is then replenished by the infall from comets.>>
<<Two examples of dust grains collected by Rosetta’s COSIMA instrument. Both grains were collected at a distance of 10–20 km from the [67P/Churyumov-Gerasimenko] nucleus. Image (a) shows a dust particle named “Eloi” that crumbled into a rubble pile when collected; (b) shows the dust particle “Arvid” that shattered. The fact that the grains broke apart so easily means their individual parts are not well glued together and probably do not contain any ice. >>
Copyright: ESA/Rosetta/MPS for COSIMA Team MPS/CSNSM/UNIBW/TUORLA/IWF/IAS/ESA/ BUW/MPE/LPC2E/LCM/FMI/UTU/LISA/UOFC/vH&S -
Sounds like the makings of a futuristic story, in time.
https://en.wikipedia.org/wiki/Cosima wrote:
<<COSIMA is the feminine version of the name Cosimo. It is derived from the Greek word meaning "order, decency." Cosmo was a fourth-century saint who was martyred with his brother Damian. They are the patron saints of medical doctors. An Italian male version of the name is Cosimo.>>
Milky Way over Bosque Alegre Station in Argentina
<<Two examples of dust grains collected by Rosetta’s COSIMA instrument. Both grains were collected at a distance of 10–20 km from the [67P/Churyumov-Gerasimenko] nucleus. Image (a) shows a dust particle named “Eloi” that crumbled into a rubble pile when collected; (b) shows the dust particle “Arvid” that shattered. The fact that the grains broke apart so easily means their individual parts are not well glued together and probably do not contain any ice. >> 
