ASTRONOMY - Introducing Comet Leonard

 2021 November 21

Introducing Comet Leonard
Image Credit & Copyright: Dan Bartlett

Explanation: Here comes Comet Leonard. Comet C/2021 A1 (Leonard) was discovered as a faint smudge in January 2021 when it was out past Mars -- but its orbit will take the giant shedding ice-ball into the inner Solar System, passing near both Earth and Venus in December before it swoops around the Sun in early January 2022. Although comets are notoriously hard to predict, some estimations have Comet Leonard brightening to become visible to the unaided eye in December. Comet Leonard was captured just over a week ago already sporting a green-tinged coma and an extended dust tail. The featured picture was composed from 62 images taken through a moderate-sized telescope -- one set of exposures tracking the comet, while another set tracking the background stars. The exposures were taken from the dark skies above the Eastern Sierras (Mountains), near June Lake in California, USA. Soon after passing near the Earth in mid-December, the comet will shift from northern to southern skies.

ASTRONOMY - An Almost Total Lunar Eclipse

 2021 November 20

An Almost Total Lunar Eclipse
Image Credit & Copyright: Robert Fedez

Explanation: Predawn hours of November 19 found the Moon in partly cloudy skies over Cancun, Mexico. Captured in this telephoto snapshot, the lunar disk is not quite entirely immersed in Earth's dark umbral shadow during a long partial lunar eclipse. The partial eclipse was deep though, deep enough to show the dimmed but reddened light in Earth's shadow. That's a sight often anticipated by fans of total lunar eclipses. Wandering through the constellation Taurus, the eclipsed Moon's dimmer light also made it easier to spot the Pleiades star cluster. The stars of the Seven Sisters share this frame at the upper right, with the almost totally eclipsed Moon.

ASTRONOMY - NGC 281: Starless with Stars

 2021 November 19

NGC 281: Starless with Stars
Image Credit & Copyright: Wido Oerlemans - X-ray: Chandra, Infrared: Spitzer

Explanation: In visible light the stars have been removed from this narrow-band image of NGC 281, a star forming region some 10,000 light-years away toward the constellation Cassiopeia. Stars were digitally added back to the resulting starless image though. But instead of using visible light image data, the stars were added with X-ray data (in purple) from the Chandra X-ray Observatory and infrared data (in red) from the Spitzer Space Telescope. The merged multiwavelength view reveals a multitude of stars in the region's embedded star cluster IC 1590. The young stars are normally hidden in visible light images by the natal cloud's gas and obscuring dust. Also known to backyard astro-imagers as the Pacman Nebula for its overall appearance in visible light, NGC 281 is about 80 light-years across.

ASTRONOMY - Full Moonlight

 2021 November 18

Full Moonlight
Image Credit & Copyright: Zhengjie Wu and Jeff Dai (TWAN)

Explanation: A photographer in silhouette stands in bright moonlight as the Full Moon rises in this well-planned telephoto image. Of course, the Full Moon is normally the brightest lunar phase. But on November 18/19, the Full Moon's light will be dimmed during a deep partial lunar eclipse seen across much of planet Earth. At maximum eclipse only a few percent of the lunar disk's diameter should remain outside the Earth's dark umbral shadow when the Moon slides close to the shadow's southern edge. Near apogee, the farthest point in its orbit, the Moon's motion will be slow. That should make this second lunar eclipse of 2021 an exceptionally long partial lunar eclipse. For most of North America the eclipse partial phases will be visible in predawn hours. Since eclipses tend to come in pairs, this lunar eclipse will be followed by a solar eclipse in two weeks on December 4.

ASTRONOMY - NGC 3314: When Galaxies Overlap

 2021 November 17

NGC 3314: When Galaxies Overlap
Image Credit: NASA, ESA, Hubble; Processing & Copyright: William Ostling (The Astronomy Enthusiast)

Explanation: Why doesn't the nearby galaxy create a gravitational lensing effect on the background galaxy? It does, but since both galaxies are so nearby, the angular shift is much smaller than the angular sizes of the galaxies themselves. The featured Hubble image of NGC 3314 shows two large spiral galaxies which happen to line up exactly. The foreground spiral NGC 3314a appears nearly face-on with its pinwheel shape defined by young bright star clusters. Against the glow of the background galaxy NGC 3314b, though, dark swirling lanes of interstellar dust can also be seen tracing the nearer spiral's structure. Both galaxies appear on the edge of the Hydra Cluster of Galaxies, a cluster that is about 200 million light years away. Gravitational lens distortions are much easier to see when the lensing galaxy is smaller and further away. Then, the background galaxy may even be distorted into a ring around the nearer. Fast gravitational lens flashes due to stars in the foreground galaxy momentarily magnifying the light from stars in the background galaxy might one day be visible in future observing campaigns with high-resolution telescopes.

ASTRONOMY - Light Pillar over Volcanic Etna

 2021 November 15

Light Pillar over Volcanic Etna
Image Credit & Copyright: Giancarlo Tinè

Explanation: What happening above that volcano? Something very unusual -- a volcanic light pillar. More typically, light pillars are caused by sunlight and so appear as a bright column that extends upward above a rising or setting Sun. Alternatively, other light pillars -- some quite colorful -- have been recorded above street and house lights. This light pillar, though, was illuminated by the red light emitted by the glowing magma of an erupting volcano. The volcano is Italy's Mount Etna, and the featured image was captured with a single shot a few hours after sunset in mid-June. Freezing temperatures above the volcano's ash cloud created ice-crystals either in cirrus clouds high above the volcano -- or in condensed water vapor expelled by Mount Etna. These ice crystals -- mostly flat toward the ground but fluttering -- then reflected away light from the volcano's caldera.

ASTRONOMY - Moon and Planets at Twilight

 2019 November 28

Moon and Planets at Twilight
Image Credit & Copyright: Petr Horálek

Explanation: This week's ongoing conjunction of Venus and Jupiter may have whetted your appetite for skygazing. Tonight is the main course though. On November 28, a young crescent Moon will join them posing next to the two bright planets above the western horizon at twilight. Much like tonight's visual feast, this night skyscape shows a young lunar crescent and brilliant Venus in the western evening twilight on October 29. The celestial beacons are setting over distant mountains and the Minya monastery, Ganzi Tibetan Autonomous Prefecture, Sichuan, China, planet Earth. Then Mercury, not Jupiter, was a celestial companion to Venus and the Moon. The fleeting innermost planet is just visible here in the bright twilight, below and left of Venus and near the center of the frame. Tomorrow, November 29, the crescent Moon will also help you spot planet Saturn for dessert.

ASTRONOMY - Rosetta's Comet in Gemini

 2021 November 13

Rosetta's Comet in Gemini
Image Credit & Copyright: Rolando Ligustri (CARA Project, CAST)

Explanation: Returning along its 6.4 year orbit, periodic comet Churyumov-Gerasimenko (67P) is caught in this telescopic frame from November 7. Sweeping past background stars in the constellation Gemini the comet's dusty tail stretches toward the upper right to Upsilon Geminorum. Also known as Pollux, Beta Geminorum, Gemini's brightest star, shines just off the upper left edge of the field-of-view. Churyumov-Gerasimenko reached its 2021 perihelion or closest approach to the Sun on November 2. At perigee, its closest approach to planet Earth on November 12, this comet was about 0.42 astronomical units away, though it remains too faint to be seen by eye alone. The well-studied comet was explored by robots from planet Earth during its last trip through the inner solar system. It's now famous as the final resting place for the historic Rosetta spacecraft and Philae lander.

ASTRONOMY - Night of the Perseids

2021 September 28

Night of the Perseids
Video Credit & Copyright: Vikas Chander & Dorje Angchuk; Music: Tea Time via PremiumBeat

Explanation: Have you ever experienced a meteor shower? To help capture the wonder, a video was taken during the peak of the recent Perseid meteor shower above the Indian Astronomical Observatory in Hanle, India, high up in the Himalayan mountains. Night descends as the video begins, with the central plane of our Milky Way Galaxy approaching from the left and Earth-orbiting satellites zipping by overhead. During the night, the flash of meteors that usually takes less than a second is artificially extended. The green glow of most meteors is typically caused by vaporizing nickel. As the video continues, Orion rises and meteors flare above the 2-meter Himalayan Chandra Telescope and the seven barrels of the High Energy Gamma Ray Telescope (Hagar). The 2 minute 30 second movie ends with the Sun rising, preceded by a false dawn of zodiacal light. 

ASTRONOMY - Video of a Green Flash

2021 November 10

Video of a Green Flash
Video Credit & Copyright: Paolo Lazzarotti

Explanation: Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from the Sun. The truth is the green flash does exist and its cause is well understood. Just as the setting Sun disappears completely from view, a last glimmer appears startlingly green. The effect is typically visible only from locations with a low, distant horizon, and lasts just a few seconds. A green flash is also visible for a rising Sun, but takes better timing to spot. A dramatic green flash was caught on video last month as the Sun set beyond the Ligurian Sea from Tuscany, Italy. The second sequence in the featured video shows the green flash in real time, while the first is sped up and the last is in slow motion. The Sun itself does not turn partly green -- the effect is caused by layers of the Earth's atmosphere acting like a prism.