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The LDN 483 Dark Nebula
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Caption: This image shows a dark molecular cloud known as LDN 483, captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. At first glance, the patch of sky looks like a region where stars are missing, but the effect is due to interstellar extinction — dust and gas within LDN 483 absorb and scatter light from background stars, making them appear faint or invisible to telescopes that observe visible light. Interstellar extinction is the dimming of light from distant objects caused by dust and gas between the object and the observer, a common phenomenon in astronomy that must be accounted for when measuring stellar brightness and color.
Dark nebulae like LDN 483 are dense concentrations of interstellar matter located within our Milky Way Galaxy. This particular cloud lies about 700 light-years from Earth in the constellation Serpens and contains enough material to block most visible light from stars behind it. Because dust grains preferentially scatter shorter (bluer) wavelengths of light, extinction can also make objects appear redder than they truly are — a related effect known as interstellar reddening. Understanding and correcting for extinction is essential for astronomers to reveal the true brightness, distance, and physical properties of celestial objects seen through dusty regions of space.
Credit: ESO
Credit Link
Glossary Terms:
Dark Nebula , Interstellar Medium , Interstellar Extinction
License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons
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( image
31.01 MB)
Between Two Skies
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Created for the OAE
Caption: Honourable mention in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.
Taken from Narrabri, Australia, in April 2014, this photograph shows a meteor next to the Large Magellanic Cloud and the reflection of all this in the water.
The Magellanic Clouds are named after the Portuguese explorer Ferdinand Magellan, who made the first maps of the southern part of South America in the early 16th century but did not survive his expedition voyage. His shipmates called the two nebulae after him, and it was only in the 20th century that astronomy research discovered that they are in fact dwarf galaxies accompanying our own.
In the 18th century, the French mathematician J-N. Lacaille, who lived in South Africa for some years in order to draw maps of the sky and the land, invented some new constellations. He measured the positions of some faint stars and listed them in his star catalogue, but did not try to overlay beautiful drawings of real-world objects on the star patterns, so he could name them however he wanted. He was based in the trade station that is now the city of Cape Town and, from this bay, Table Mountain is visible. Lacaille learned from the navigators that they used the clouds around this mountain to predict whether or not the wind would blow in the correct direction and allow for sailing. Normally, there is a huge white cloud at the top of Table Mountain, so Lacaille considered the larger one of the two dwarf galaxies not a “Magellanic Cloud”, but the cloud at Table Mountain. Consequently, he invented the constellation “Mensa”, Table Mountain, in the small area of faint stars directly attached to this dwarf galaxy.
Credit: Fabrizio Melandri/IAU OAE
Glossary Terms:
Constellation , Shooting Star , Large Magellanic Cloud (LMC) , Small Magellanic Cloud (SMC)
Categories:
Galaxies
, Naked Eye Astronomy
License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons
This file on Zenodo ( image 1.82 MB)
A Geocentric chart from 1568
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Caption: This map, created in 1568 by the Portuguese cartographer Bartolomeu Velho, depicts the worldview of the time, when many scholars believed in a geocentric model of the cosmos — the idea that Earth sits at the centre of the Universe with the Sun, Moon, the five planets known at the time, and stars moving around it. The design and layout of this map were influenced by astronomical understanding rooted in geocentric thinking.
The geocentric model was widely accepted for many centuries, especially in Europe, based on interpretations of celestial motions and philosophical traditions that placed Earth at the centre. It was only later, with observations by astronomers such as, Galileo Galilei, that this model was replaced by the heliocentric model, which places the Sun at the centre of the Solar System.
Credit: Bartolomeu Velho
Credit Link
Glossary Terms:
Geocentric Model , Scientific Model
License: Public Domain Public Domain icons
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( image
12.99 MB)
Oregon Coast
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Created for the OAE
Caption: Honourable mention in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns:.
This image features the Milky Way, our home galaxy, over Oregon, USA, as seen in July 2021. It is obviously a composite because the stars are not reflected in the water. Still, it is nicely composed to suggest a similarity between the stream of water on Earth and the (mirrored) stream of stars in the sky.
The Milky Way clearly dominates the sky in this image. As a prominent feature in the sky, the Milky Way has been associated with the religions and mythologies of many cultures. The best-known association from Greek folklore “explains” it as a stream of divine milk from the mighty mother goddess Hera, whose husband god Zeus frequently misbehaved (as he did in this case, causing this accident). Greek mythology, on the other hand, considered it to be the path of the souls, while ancient Greek science suggested several scientific explanations, all of which turned out to be false.
The Ojibwe in North America, who live to the east of Oregon where this photograph was taken, also consider the Milky Way a Path for Spirits and a River of Souls. Looking at the foreground of the picture, this belief is even more understandable; it looks as if the rivers of Earth and heaven merge at the horizon.
The prominent feature in the middle of the image is the dark region called the Pipe Nebula in the Milky Way. The smoke of this pipe goes to the right and ends almost at a treetop, where we find the orange star Antares in the heart of the Scorpion.
In the middle of the image, below the Pipe, there is a huge dark area in the Milky Way with two prominent red spots. These spots are hydrogen clouds called the Cat’s Paw and the Lagoon, but in this image they look like the red eyes of great Manitou, the Great Spirit of the Iroquois Native Americans. The constellation of Sagittarius in this area is not recognisable because the image of the Milky Way is highly processed in order to display these dark features that are invisible to the naked eye.
Credit: Marcin Zajac/IAU OAE
Glossary Terms:
Dust , Milky Way , Dust Cloud , Interstellar Extinction
Categories:
Milky Way and Interstellar Medium
, Naked Eye Astronomy
License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons
This file on Zenodo ( image 16.36 MB)
Moon-Mercury-Pleiades Conjunction
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Created for the OAE
Caption: Honourable mention in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.
This photograph shows the young lunar crescent, some of the nine brightest stars of the Pleiades (with one behind a cloud) on the right, and the planet Mercury, looking slightly red, in the middle of the image.
This picture is rather suggestive of the idea that the Pleiades might possibly consist of seven stars. However, the viewer is misled by the clouds; five of the stars form a tiny chariot, one is next to the handle, and three are at the other end of the quadrilateral. Eight stars would be clearly visible if there were no clouds.
This configuration of the young Moon next to the Pleiades is visible only in the northern hemisphere spring. Thus it was used by the ancient Babylonians to determine the second month of their year and to judge whether or not an intercalary month was necessary. At least as early as the second millennium before the common era, the Babylonians used several asterisms for each month, with another one of them reappearing every five days after invisibility during daylight. To determine the necessity of intercalation in order to synchronise the solar and the lunar year, the Babylonians used several asterisms, not only the Pleiades. For instance, they also made use of the bright stars Arcturus and Sirius, and they observed a configuration with the Moon as well as heliacal phenomena. The modern Jewish and modern Islamic traditions still make use of some of the Babylonian astronomical rules. However, given that the constellations have shifted as a result of precession, and the fact that nowadays we also have computational means to calculate our calendars, this configuration of the small crescent Moon and the Pleiades is less useful, though it remains exceptionally beautiful. Thus the ancient Babylonian and middle Babylonian tradition survives only rudimentarily. Furthermore, it is unlikely that it is depicted in the Nebra Disc from Bronze Age Europe, as has long been claimed.
This image was taken on Elba Island, Italy, in May 2022.
Credit: Giulio Colombo/ IAU OAE
Glossary Terms:
Conjunction , Mercury , Moon , Waxing Crescent , Crescent Moon , Pleiades
Categories:
Naked Eye Astronomy
License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons
This file on Zenodo ( image 420.90 kB)
