Documents & Ressources - Résultat de la recherche
Résultats de la recherche
The Callisto satellite
image
Légende : Callisto is the outermost of the four large Galilean moons of Jupiter and the third largest in the whole solar system, falling behind only Ganymede and Saturn's moon Titan. It orbits Jupiter at an average distance of around 1.9 million kilometers, roughly six times the distance between Earth and the Moon.
With a diameter of nearly 5,000 kilometers, it is almost as large as Mercury, the smallest planet in our solar system, but has only a third of its mass as it is composed of approximately equal amounts of rock and ice.
Callisto orbits Jupiter in a tidally locked rotation, always showing the same side to Jupiter. In contrast to the other three Galilean satellites – Io, Europa, and Ganymede – it is not in orbital resonance due to its farther outward location and is thus not appreciably tidally heated. It does not show any signs of plate tectonics or volcanic activity. Its lack of geological processes means that surface features like craters remain unchanged for billions of years. It is thought to have evolved predominantly under the influence of impacts, as its surface is the oldest and most heavily cratered object in the solar system. In fact, it is so covered in craters that any new impact will likely erase a former one.
Callisto's internal structure is still subject to discussion; it may consist of a deep salty ocean. It is thought to be composed mainly of a mix of ice and rock, which are present in various states throughout the inner layers of the moon. Callisto hosts a very thin atmosphere composed mainly of carbon dioxide and some traces of oxygen. The moon has been studied by numerous space probes, such as the Pioneer and Voyager missions and the Galileo orbiter, and will be subject to further explorations by NASA, ESA, and China’s National Space Administration (CNSA).
Crédit : NASA/JPL/DLR
Lien du crédit
Termes du glossaire:
Satellites galiléens , Lunes
Licence : Domaine Public Domaine Public Icônes
Fichier
( image
610.45 kB)
Milky Way Arch over Lut Desert, Iran, by Amirreza Kamkar, Iran (Islamic Republic of)
image
Créé pour l'OAE
Légende : Second place in the 2021 IAU OAE Astrophotography Contest, category Wide star fields.
This panoramic dawn image shows the majestic band of the Milky Way – our home Galaxy – made up of a few hundred billion stars, among other structures, most of which are not detectable by our eyes, or in some cases even directly with telescopes. The appearance of the band is because the Milky Way is a disc-shaped galaxy, and we (Earth/Solar System) are situated within the disc.
Diverse cultures and traditions around the world each have their own name and cultural stories for the Milky Way. The dark regions visible in the Milky Way are large, dense, cool nebulae (clouds of dust and gas), which obscure the light from stars in the Milky Way. The Indigenous Australians associate stories with the dark patches of the Milky Way, one of the most prominent being the Emu in the Sky (called Tchingal in Wotjobaluk country). In and around the band of the Milky Way there are a vast range of star clusters, two familiar ones are M6 (Butterfly cluster) and M7 (Ptolemy’s cluster).
The bright point just above the horizon is the planet Venus (known to the Boorong people of Indigenous Australia as Chargee Gnowee, elder sister of the Sun). Within the band of the Milky Way the brightest point in the image is the planet Jupiter (called Ginabongbearp, the Sulphur-crested white cockatoo by the Boorong). The planet Saturn is the bright point between Venus and Jupiter (closer to Venus than Jupiter).
There are two constellations and one asterism that can be easily discerned in the image: Aquila, Scorpio (Maui’s Hook), and Teapot (asterism in Sagittarius). In this image, the center of the Milky Way at an approximate distance of 26,000 light years from Earth, is located roughly to the top right of the Teapot spout.
The bright red-orange point to the right of Jupiter is the red supergiant star Antares and is part of the constellation Scorpio (known as Maui’s Hook in Māori and Polynesian cultures). This variation in the colour of stars is the result of temperature of the stars (lower temperature stars are redder, higher temperatures stars are bluer).
Crédit : Amirreza Kamkar/IAU OAE
Termes du glossaire:
Voie lactée , Nuage de poussière
Catégories :
Voie lactée et milieu interstellaire
, Astronomie à l'œil nu
Licence : Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Icônes
Ce fichier est sur Zenodo ( image 2.85 MB)
Chilean observatories at home office, by Robert Barsa, Slovakia
image
Créé pour l'OAE
Légende : Third place in the 2021 IAU OAE Astrophotography Contest, category Wide star fields.
This rich panoramic image shows a range of constellations, deep sky objects and planets. The brightest point of light with a pale reddish hue (left of center) is the planet Mars. In the bottom far left of the image, located just above the sloped roof of the building are two points of light appearing very close to each other, these are the planets Jupiter (brighter) and Saturn. To the far right of the image the two fuzzy cloud-like objects are the Large and Small Magellanic Clouds. These are satellite dwarf galaxies of the Milky Way located at a distance of approximately 160,000 and 200,000 light years, respectively. The Andromeda Galaxy, which is located at an approximate distance of 2.5 million light years, appears in this image as a small, angled smudge between Mars and the brightest glow on the horizon (closer to the horizon). The bright glow is not from the Sun or the Moon, but the city lights of San Pedro de Atacama.
Prominent constellations include: Orion – identified by the three stars forming Orion’s Belt; Taurus – a small triangle shaped collection of stars to the left of Orion and identified by the pale orange star (Aldebaran) at the vertex of the triangle; Canis Major – to the bottom right of Orion, identified by the bright star Sirius (the brightest star in the night sky) and three stars in the shape of a triangle just above the observatory dome in the foreground; Pegasus – identified by the trapezium shape diagonally below Mars. Other constellations include Andromeda, Perseus and Aries. Diverse cultures around the world have their own names and rich stories associated with these constellations and many others.
To the top right of Orion’s Belt is an angled line of stars (Orion’s Sword) within which is a pinkish smudge (looks like a fuzzy star when observed with the unaided eye) that is the Orion Nebula – a stellar nursery located 1500 light years from Earth – where stars are formed. To the left of Taurus is a compact fuzzy smudge, and that is the Pleiades star cluster. The variation in the colour of stars is the result of temperature of the stars, for example, the red orange star to the bottom left of Orion’s Belt is the red giant star Betelgeuse. Cooler stars appear redder, compared to the higher temperature white and bluish stars. The colours in the image are enhanced because of the higher sensitivity of the digital camera compared to the human eye.
Crédit : Robert Barsa/IAU OAE
Termes du glossaire:
Bélier , Astronomie , Observatoire
Catégories :
Astronomie à l'œil nu
, Télescopes, instruments et observatoires
Licence : Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Icônes
Ce fichier est sur Zenodo ( image 77.18 MB)
- Ressources
- Moteur de recherche des ressources pédagogiques
- Parcourir les ressources pédagogiques par Sujet
- Parcourir les images
- AstroEdu - Activités en classe
- Grandes Idées - Littéracie en astronomie
- Glossaire
- Rapports de l'OAE
- L'astronomie pour l'Education à travers le monde
- Sélection de ressources externes