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The Elephant s Trunk Nebula in Cepheus

Like an illustration in a galactic Just So Story, the Elephant’s Trunk Nebula winds through the emission nebula and young star cluster complex IC 1396, in the high and far off constellation of Cepheus. Also known as vdB 142, the cosmic elephant’s trunk is over 20 light-years long. This colorful close-up view was recorded through narrow band filters that transmit the light from ionized hydrogen, sulfur, and oxygen atoms in the region. The resulting composite highlights the bright swept-back ridges that outline pockets of cool interstellar dust and gas. Such embedded, dark, tendril-shaped clouds contain the raw material for star formation and hide protostars within. Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a large region on the sky, spanning over 5 degrees. The dramatic scene spans a 1 degree wide field, about the size of 2 Full Moons. via NASA

Saturn Behind the Moon

What’s that next to the Moon? Saturn. In its monthly trip around the Earth — and hence Earth’s sky — our Moon passed nearly in front of Sun-orbiting Saturn earlier this week. Actually the Moon passed directly in front of Saturn from the viewpoints of a wide swath of Earth’s Southern Hemisphere. The featured image from Sydney, Australia captured the pair a few minutes before the eclipse. The image was a single shot lasting only 1/500th of a second, later processed to better highlight both the Moon and Saturn. Since Saturn is nearly opposite the Sun, it can be seen nearly the entire night, starting at sunset, toward the south and east. The gibbous Moon was also nearly opposite the Sun, and so also visible nearly the entire night — it will be full tomorrow night. The Moon will occult Saturn again during every lap it makes around the Earth this year. via NASA

Jupiter Engulfed and the Milky Way

This is a good month to see Jupiter. To find our Solar System’s largest planet in your sky, look toward the southeast just after sunset — Jupiter should be the brightest object in that part of the sky. If you have a binoculars or a small telescope, you should be able to see Jupiter’s four brightest moons right nearby, and possibly some cloud bands. The featured image was taken about a month ago from the Persian Gulf. The image shows Jupiter just to the right of the nearly vertical band of the central disk of our Milky Way Galaxy. The unnamed rock formations appear in projection like the jaws of a giant monster ready to engulf the Jovian giant. When you see Jupiter, it may be interesting to know that NASA’s robotic Juno spacecraft is simultaneously visiting and studying the giant planet. Saturn is also visible this month, and although it is nearby to Jupiter, it is not as bright. via NASA

A Total Solar Eclipse Reflected

If you saw a total solar eclipse, would you do a double-take? One astrophotographer did just that — but it took a lake and a bit of planning. Realizing that the eclipse would be low on the horizon, he looked for a suitable place along the thin swath of South America that would see, for a few minutes, the Moon completely block the Sun, both directly and in reflection. The day before totality, he visited a lake called La Cuesta Del Viento (The Slope of the Wind) and, despite its name, found so little wind that the lake looked like a mirror. Perfect. Returning the day of the eclipse, though, there was a strong breeze churning up the water — enough to ruin the eclipse reflection shot. Despair. But wait! Strangely, about an hour before totality, the wind died down. This calmness may have been related to the eclipse itself, because eclipsed ground heats the air less and reduces the amount rising warm air — which can dampen and even change the wind direction. The eclipse came, his tripod and camera were ready, and so was the lake. The featured image of this double-eclipse came from a single exposure lasting just one fifteenth of a second. Soon after totality, the winds returned and the water again became choppy. No matter — this double-image of the 2019 July total solar eclipse had been captured forever. via NASA

Rumors of a Dark Universe

Twenty-one years ago results were first presented indicating that most of the energy in our universe is not in stars or galaxies but is tied to space itself. In the language of cosmologists, a large cosmological constant — dark energy — was directly implied by new distant supernova observations. Suggestions of a cosmological constant were not new — they have existed since the advent of modern relativistic cosmology. Such claims were not usually popular with astronomers, though, because dark energy was so unlike known universe components, because dark energy’s abundance appeared limited by other observations, and because less-strange cosmologies without a signficant amount of dark energy had previously done well in explaining the data. What was exceptional here was the seemingly direct and reliable method of the observations and the good reputations of the scientists conducting the investigations. Over the two decades, independent teams of astronomers have continued to accumulate data that appears to confirm the existence of dark energy and the unsettling result of a presently accelerating universe. In 2011, the team leaders were awarded the Nobel Prize in Physics for their work. The featured picture of a supernova that occurred in 1994 on the outskirts of a spiral galaxy was taken by one of these collaborations. via NASA

Mimas in Saturnlight

Peering from the shadows, the Saturn-facing hemisphere of Mimas lies in near darkness alongside a dramatic sunlit crescent. The mosaic was captured near the Cassini spacecraft’s final close approach on January 30, 2017. Cassini’s camera was pointed in a nearly sunward direction only 45,000 kilometers from Mimas. The result is one of the highest resolution views of the icy, crater-pocked, 400 kilometer diameter moon. An enhanced version better reveals the Saturn-facing hemisphere of the synchronously rotating moon lit by sunlight reflected from Saturn itself. To see it, slide your cursor over the image (or follow this link). Other Cassini images of Mimas include the small moon’s large and ominous Herschel Crater. via NASA

Chamaeleon II Dark Cloud

A small constellation hiding near the south celestial pole, The Chamaeleon boasts no bright stars. Stars are forming within its constellation boundaries though, in a complex of dark, dusty molecular clouds. Some 500 light-years distant, the Chamaeleon II dark nebula inhabits this view where the cosmic dust clouds standout mostly in silhouette against the starry southern sky. The telescopic frame is about the angular size of a Full Moon and so spans about 5 light-years at the dark cloud’s estimated distance. Scattered near center a telltale reddish glow from identified Herbig-Haro objects is seen in the sharp image, jets of shocked glowing gas emanating from recently formed stars. via NASA

IC 1795: The Fishhead Nebula

To some, this nebula looks like the head of a fish. However, this colorful cosmic portrait really features glowing gas and obscuring dust clouds in IC 1795, a star forming region in the northern constellation Cassiopeia. The nebula’s colors were created by adopting the Hubble color palette for mapping narrow emission from oxygen, hydrogen, and sulfur atoms to blue, green and red colors, and further blending the data with images of the region recorded through broadband filters. Not far on the sky from the famous Double Star Cluster in Perseus, IC 1795 is itself located next to IC 1805, the Heart Nebula, as part of a complex of star forming regions that lie at the edge of a large molecular cloud. Located just over 6,000 light-years away, the larger star forming complex sprawls along the Perseus spiral arm of our Milky Way Galaxy. At that distance, this picture would span about 70 light-years across IC 1795. via NASA

Star Forming Region NGC 3582 without Stars

What’s happening in the Statue of Liberty nebula? Bright stars and interesting molecules are forming and being liberated. The complex nebula resides in the star forming region called RCW 57, and besides the iconic monument, to some looks like a flying superhero or a weeping angel. By digitally removing the stars, this image showcases dense knots of dark interstellar dust, fields of glowing hydrogen gas ionized by these stars, and great loops of gas expelled by dying stars. A detailed study of NGC 3576, also known as NGC 3582 and NGC 3584, uncovered at least 33 massive stars in the end stages of formation, and the clear presence of the complex carbon molecules known as polycyclic aromatic hydrocarbons (PAHs). PAHs are thought to be created in the cooling gas of star forming regions, and their development in the Sun’s formation nebula five billion years ago may have been an important step in the development of life on Earth. via NASA

HDR: Earths Circular Shadow on the Moon

What could create such a large circular shadow on the Moon? The Earth. Last week’s full Moon — the Buck Moon — was so full that it fell almost exactly in a line with the Sun and the Earth. When that happens the Earth casts its shadow onto the Moon. The circularity of the Earth’s shadow on the Moon was commented on by Aristotle and so has been noticed since at least the 4th century BC. What’s new is humanity’s ability to record this shadow with such high dynamic range (HDR). The featured HDR composite of last week’s partial lunar eclipse combines 15 images and include an exposure as short as 1/400th of a second — so as not to overexpose the brightest part — and an exposure that lasted five seconds — to bring up the dimmest part. This dimmest part — inside Earth’s umbra — is not completely dark because some light is refracted through the Earth’s atmosphere onto the Moon. A total lunar eclipse will occur next in 2021 May. via NASA