Posts tagged moon

Posted 1 year ago

The Moon’s Saturn 
Image Credit & Copyright: Jens Hackmann

Explanation: Just days after sharing the western evening sky with Venus in 2007, the Moon moved on to Saturn - actually passing in front of the ringed planet Saturn when viewed in skies over Europe, northern Africa, and western Asia. Because the Moon and bright planets wander through the sky near the ecliptic plane, such occultation events are not uncommon, but they are dramatic, especially in telescopic views. For example, in this sharp image Saturn is captured emerging from behind the Moon, giving the illusion that it lies just beyond the Moon’s bright edge. Of course, the Moon is a mere 400 thousand kilometers away, compared to Saturn’s distance of 1.4 billion kilometers. Taken with a digital camera and 20 inch diameter telescope at the Weikersheim Observatory in southern Germany, the picture is a single exposure adjusted to reduce the difference in brightness between Saturn and the cratered lunar surface.

Posted 1 year ago

Moon or Frying Pan? 
Images Credit: Frying Pan (Copyrighted): Christopher JonassenMoon: NASA

Explanation: Which is which? Of the two images shown above, one is a moon in our Solar System, while the other is the bottom of frying pan. We are not making this up — can you tell a pan from a planetoid? Think you got it? To find the answer click here. OK, but there are more! That’s right: you, your family, friends, neighbors, and local elected officials can all play “Moon or Frying Pan” with these other image pairs, too. As everyone knows, the fundamental underlying reason why moons and frying pans appear similar is — OK, we at APOD aren’t sure either. And if you’ve been fooled, don’t fret — just remember that it’s OK because today is April Fool’s Day.

Posted 1 year ago

Ringside with Rhea 
Image Credit: Cassini Imaging TeamSSIJPLESANASA

Explanation: Orbiting in the plane of Saturn’s rings, Saturnian moons have a perpetual ringside view of the gas giant planet. Of course, while passing near the ring plane the Cassini spacecraft also shares their stunning perspective. The thin rings themselves slice across the middle of this Cassini snapshot from April 2011. The scene looks toward the dark night side of Saturn, in the frame at the left, and the still sunlit side of the rings from just above the ringplane. Centered, over 1,500 kilometers across, Rhea is Saturn’s second largest moon and is closest to the spacecraft, around 2.2 million kilometers away. To Rhea’s right, shiny, 500 kilometer diameter Enceladus is about 3 million kilometers distant. Dione, 1,100 kilometers wide, is 3.1 million kilometers from Cassini’s camera on the left, partly blocked by Saturn’s night side.

Posted 1 year ago

GRAIL Maps the Moon’s Gravity 
Image Credit & Copyright: NASAJPL-CaltechMITGSFCSVC

Explanation: How did the Moon form? To help find out, NASA launched the twin Gravity Recovery and Interior Laboratory(GRAIL) satellites in 2011 to orbit and map the Moon’s surface gravity in unprecedented detailPictured above is a resultingGRAIL gravity map, with regions of slightly lighter gravity shown in blue and regions of slightly stronger gravity shown in red. Analysis of GRAIL data indicates that the moon has an unexpectedly shallow crust than runs about 40 kilometers deep, and an overall composition similar to the Earth. Although other surprising structures have been discovered that will continue to be investigated, the results generally bolster the hypothesis that the Moon formed mostly from Earth material following a tremendous collision in the early years of our Solar System, about 4.5 billion years ago. After completing their mission and running low on fuel, the two GRAIL satellites, Ebb and Flow, were crashed into a lunar crater at about 6,000 kilometer per hour.

Posted 1 year ago

PanSTARRS from France 
Image Credit & CopyrightJean-Luc Dauvergne

Explanation: Still looking for that comet? Comet PanSTARRS (C/2011 L4) naked-eye appearance in the northern hemisphere is described by successful comet spotters as a dim star with a faint tail. If you want to catch it the next few days could be your best bet.Start looking low and almost due west about 45 minutes after sunset. Of course, clear skies and a pair of binoculars should help a lot. Sky photographer Jean-Luc Dauvergne found suitable weather and western horizon for this comet and crescent Moon portrait after a road trip on March 13. Seeing PanSTARRS for the first time, he recorded the beautiful twilight scene with a telephoto lens nearhistorical Alesia in France.

Posted 1 year ago

Clouds, Comet and Crescent Moon 
Image Credit & CopyrightBabak Tafreshi (TWAN)

Explanation: In silhouette against the colorful evening twilight, clouds part for this much anticipated magic moment. The scene captures naked-eye Comet PanSTARRS peeking into northern hemisphere skies on March 12. The comet stands over the western horizon after sunset, joined by the thin, flattened crescent of a day old Moon. Posing for its own beauty shot, the subtly lit dome of the 4.2 meter William Herschel Telescope is perched above cloud banks on the Canary Island of La Palma. While PanSTARRS has not quite developed into the spectacular comet once hoped for, it is still growing easier to see in the north. In coming days it will steadily climb north, farther from the Sun into darker western evening skies.

Posted 1 year ago

Tardigrade in Moss 
Image Credit & Copyright: Nicole Ottawa & Oliver Meckes / Eye of Science / Science Source Images

Explanation: Is this an alien? Probably not, but of all the animals on Earth, the tardigrade might be the best candidate. That’s becausetardigrades are known to be able to go for decades without food or water, to survive temperatures from near absolute zero to well above the boiling point of water, to survive pressures from near zero to well above that on ocean floors, and to survive direct exposure to dangerous radiations. The far-ranging survivability of these extremophiles was tested in 2011 outside an orbiting space shuttle. Tardigrades are so durable partly because they can repair their own DNA and reduce their body water content to a few percent. Some of these miniature water-bears almost became extraterrestrials recently when they were launched toward to the Martian moon Phobos on board the Russian mission Fobos-Grunt, but stayed terrestrial when a rocket failed and the capsule remained in Earth orbit. Tardigrades are more common than humans across most of the Earth. Pictured above in a color-enhanced electron micrograph, a millimeter-long tardigrade crawls on moss.

Posted 1 year ago

Snow Moon for a Snowy Planet 
Image Credit & CopyrightGöran Strand

Explanation: The alarmingly tall inhabitants of this small, snowy planet cast long shadows in bright moonlight. Of course, the snowy planet is actually planet Earth and the wide-angle mosaic, shown as a little planet projection, was recorded on February 25 during the long northern night of the Full Snow Moon. The second brightest celestial beacon is Jupiter, on the right above the little planet’s horizon. Lights near Östersund, Sweden glow along the horizon, surrounding the snow covered lake Storsjön. The photographer reports that the journey out onto the frozen lake by sled to capture the evocativeFull Snow Moon scene was accompanied by ice sounds, biting cold, and a moonlit mist.

Posted 1 year ago

Fly Me to the Moons 
Image Credit & Copyright: Greg Gibbs (Capturing the Night

Explanation: Sometimes the Moon is a busy direction. Last week, for example, our very Moon passed in front of the planet Jupiter. While capturing this unusual spectacle from New South WalesAustralia, a quick-thinking astrophotographer realized that a nearby plane might itself pass in front of the Moon, and so quickly reset his camera to take a continuous series of short duration shots. As hoped, for a brief instant, that airplane, the Moon, and Jupiter were all visible in a single exposure, which is shown above. But the project was not complete — a longer exposure was then taken to bring up three of the Jupiter’s own moons: Io, Calisto, and Europa (from left to right). Unfortunately, this triple spectacle soon disappeared. Less than a second later, the plane flew away from the Moon. A few seconds after that, the Moonmoved to cover all of Jupiter. A few minutes after that, Jupiter reappeared on the other side of the Moon, and even a few minutes after that the Moon moved completely away from Jupiter. Although hard to catch, planes cross in front of the Moon quite frequently, but the Moon won’t eclipse Jupiter again for another three years.

Posted 1 year ago

Asteroid 2012 DA14 Passes the Earth 
Video Credit & Copyright: Daniel López (El Cielo de Canarias)

Explanation: There it goes. That small spot moving in front of background stars in the above video is a potentially dangerous asteroid passing above the Earth’s atmosphere. This past Friday, the 50-meter wide asteroid 2012 DA14 just missed the Earth, passing not only inside the orbit of the Moon, which is unusually close for an asteroid of this size, but also inside the orbit of geosynchronous satellites. Unfortunately, asteroids this big or bigger strike the Earth every 1000 years or so. Were2012 DA14 to have hit the Earth, it could have devastated a city-sized landscape, or stuck an ocean and raised dangerous tsunamis. Although finding and tracking potentially dangerous asteroids is a primary concern of modern astronomy, these small bodies or ice and rock are typically so dim that only a few percent of them have been found, so far. Even smaller chunks of ice and rock, like the (unrelated) spectacular meteors that streaked over Russia and California over the past few days, are even harder to find — but pose less danger.