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Pioneer Plaques
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Caption: The Pioneer 10 and 11 spacecraft are the first human-made objects to leave the solar system and venture into interstellar space. To inform potentially intelligent species about our existence, they both carry small metal plaques identifying their time, place of origin and information about their builders. They provide the location of our solar system in the Milky Way by depicting the Solar System's position relative to 14 pulsars, with radiating lines that include information about their frequencies. A model of a hydrogen atom undergoing one particular atomic transition is depicted. The wavelength and frequency of this transition are used to express sizes and frequencies of the other items shown in the plaque. A more detailed view of Earth's position in the solar system, with the spacecraft's trajectory moving away from Earth, passing Mars and Jupiter is displayed at the bottom. The plaque also depicts a naked man and woman alongside the spacecraft to provide a sense of scale. The man’s hand is raised as a friendly gesture.
The 6-inch by 9-inch gold-anodized aluminum plate has the design engraved on it. It was attached to the support struts of the spacecraft's antenna to try to to protect it from erosion by any interstellar dust the spacecraft may encounter on its journey. Designed by Carl Sagan and Frank Drake, with artwork by Linda Salzman Sagan, these plaques are meant to communicate the origin of the spacecraft to any extraterrestrial life that might encounter them.
While Pioneer 10 is on a course towards the star Aldebaran in the Taurus constellation, which will take about two million years to reach, Pioneer 11 is heading in a different direction towards the constellation of Aquila. It will take approximately four million years to pass close to some of the constellation’s stars.
Credit: NASA Ames
Credit Link
Glossary Terms:
Extraterrestrial Intelligence
Categories:
Astronomy and Society
, Exoplanets & Astrobiology
, Space Exploration
License: Public Domain Public Domain icons
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5.94 MB)
The Wild Duck Open Cluster
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Caption: This image shows the Wild Duck Cluster (also known as Messier 11 or M11), a bright grouping of stars that forms what astronomers call an open cluster in our Milky Way galaxy. Open clusters are collections of stars that were born from the same giant cloud of gas and dust and are still loosely held together by gravity. Most open clusters will slowly fall apart over hundreds of millions of years are they orbit through the galaxy. In this view, hundreds of stars appear close together against the dark background of space, with many shining at different brightnesses depending on their size and temperature.
The Wild Duck Cluster lies about 6,000 light-years from Earth and is around 300 million years old. Because the stars in an open cluster share a common origin, astronomers can use them as laboratories for testing theories on stellar evolution and behaviour.
Credit: NASA/JPL
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Glossary Terms:
Messier Object , Open Cluster
License: Public Domain Public Domain icons
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472.01 kB)
Halley's Comet
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Caption: Halley’s Comet, is a well-known periodic comet, named after the English astronomer Edmond Halley. It has an orbital period of approximately 75 years and is visible from Earth with the naked eye when it passes through the inner solar system.
The image shows Halley’s Comet, officially designated 1P/Halley, with a tail of gas and dust streaming away from the Sun. It was taken from the La-Silla-Observatory in Chile in 1986 during Halley's Comet's last visit to the inner solar system. The stars in this image appear elongated or as lines of three different colored dots as image was created from three separate observations in different colors of light and the telescope was tracking the comet, which was moving very slightly compared to the background stars. Note that the comets tail does not point in exactly the same direction as the elongation of the stars. This shows us that the comet tail is not always behind the comet, but instead pointing away from the Sun.
The comet passes its perihelion (closest distance to the Sun) at a distance of around 0.59 astronomical units, right between the orbits of Mercury and Venus. Beyond Neptune, it reaches its aphelion (furthest distance from the Sun) at a distance of approximately 35 astronomical units. Halley's Comet reached aphelion in December 2023 and is now moving inwards again. It is expected to be seen with the naked eye from Earth again in mid-2061.
Credit: ESO
Credit Link
Glossary Terms:
Aphelion , Comet , Cometary Tail , Halley's Comet , Perihelion
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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5.23 MB)
The Hunter in the Forest
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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 in December 2016, this image shows a clear and starry sky over the Masaya Volcano National Park in Nicaragua.
The constellation Orion is the most prominent pattern in this image. Orion is associated with a great hunter according to Greek culture, and is seen here right in the middle. The reddish star in the centre is Betelgeuse, the second-brightest in this constellation and one of the brightest in the night sky. Above and to the right of Betelgeuse we find Bellatrix, another bright star, forming the right shoulder of the hunter. Extending a line from Bellatrix to the right, we find a crookedly aligned group of faint stars comprising Orion’s bow. We can also easily see a group of three aligned bright stars forming the belt of the hunter, an asterism recognised by many different cultures. Just below his belt we can see the silverish glittering that was interpreted as the metal of Orion’s sword or knife by the Greco-Roman tradition. It was alternatively interpreted as a fish roasted on a campfire by some cultures in Australia. In its centre, with binoculars we can see the Small and the Great Orion Nebula, together forming a giant cloud of dust and gas where new stars are being formed. To the lower-left of the silverish compound of tiny stars and nebulae, there is a bright star called Saiph, the Arabic term for “Sword” or “Sabre” because it was considered the tip of a huge knife with a curved upper part. To the right of this, there is the bright bluish star Rigel, an Arabic term which designates it as The Foot of Orion.
Orion’s Belt points up towards Aldebaran at the edge of the photograph and down towards Sirius among the branches of the trees; it is the brightest star in the night sky and is located in the constellation Canis Major. Earth’s atmosphere makes the bright Sirius twinkle in all colours. Seen from space it is pure white, but as its light travels through the air, it is scattered and distorted by the molecules. Therefore, the star appears to change colour like a diamond.
A line connecting the two shoulders of Orion points to another bright star in the lower-left corner of the photograph. This is Procyon, located in the constellation Canis Minor. Procyon has been used by the ancient Babylonians to indicate the heliacal rise of Cancer (whose stars are faint, and invisible in twilight) and to predict the rising of Sirius. Thus, for a very long time in ancient history Procyon was considered a single-star asterism. Perhaps only in Roman times were more stars used to create a constellation in this area of the sky, although this constellation has never been clearly recognisable.
Credit: René Antonio Urroz Álvarez/IAU OAE
Glossary Terms:
Constellation , Orion
Categories:
Naked Eye Astronomy
, Stars
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 2.04 MB)
