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Half day exposure to the north star, by Fabrizio Melandri, Italy
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Created for the OAE
Caption: First place in the IAU OAE Astrophotography Contest, category Star trails.
This star trail image shows the apparent movement of the stars in the night sky, which results from the Earth’s rotation around its polar axis. The trees in the foreground serve as an anchor as we turn with the Earth. The bright white semi-circle in the center of the image is the North (Pole) star – Polaris, which is located very close to the North Celestial Pole. One way to imagine that the Earth is at center of hollow crystal sphere, and the stars are embedded on this sphere, as the Earth spins on its axis, an observer on Earth sees the stars rising and setting, following an arc, because the horizon prevents the observer from the full arc for stars that are further away from the Celestial Pole. The North Celestial Pole (and its opposite the South Celestial Pole) is essentially formed by extending the line of the Earth’s axis. Capturing this image requires the photographer to take a long exposure with the camera on a tripod and pointing towards the Pole Star (North Hemisphere). In the Southern Hemisphere there is no star as close as Polaris is to the Celestial Pole, so the position of the South Celestial Pole is found using the South Cross and Pointer Stars (Alpha and Beta Centauri). Although overall the image has a slight blue tint, it does capture the varying colours of stars, it is easy to distinguish between the higher temperature blue stars and the lower temperature of the whitish stars, and even lower temperature reddish stars. The reason for this variation in colour is because higher temperature stars emit more in shorter wavelengths (bluer), compared to lower temperature stars which emit in longer wavelengths (redder).
Credit: Fabrizio Melandri/IAU OAE
Glossary Terms:
Circumpolar Stars , Star Trail
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 6.11 MB)
Stone Star Circles, Startrails above Stonehenge, by Till Credner, Germany
image
Created for the OAE
Caption: Second place in the IAU OAE Astrophotography Contest, category Star trails.
Astronomy is one of the oldest (if not the oldest) of the sciences, and as such has connection to various cultures over millennia. This image in a way conveys this relationship by being contextualised in Stonehenge. There is much research into what astronomers call archeoastronomy sites, and how they connect to the sky (for example, seasons, phases of the moon and much more). Civilizations across time and from all over the world have their own views and interpretations of what they see in the sky, and this has been tied not only to culture but also to the people’s day-to-day and seasonal activities. The “concentric circles” which are often referred to as “star trails”, are the result of the apparent motion of the sky, which is in reality due to the rotation of the Earth on its axis. The small dot appearing towards the top center of the image is Polaris – The North or Pole Star. Polaris is only visible to observers in the Northern latitudes. The height of the Pole Star can be used to infer the observer’s actual latitude. Stonehenge is located at around 51° North. This image is taken from one of the most notable ancient sites in the world, brings us back in time, and makes us wonder about the stories told by the people that lived in that place many millennia ago.
Credit: Till Credner/IAU OAE
Glossary Terms:
Circumpolar Stars , Star Trail
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 1.26 MB)
Stars in globular clusters near the heart of the Milky Way
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Caption: This Hubble Space Telescope image presents a view of the interiors of the densely packed globular cluster Terzan 9 which consists of millions of stars located close to the heart of our Milky Way galaxy. This globular cluster sits within the central galatic bulge amidst interstellar dust, which obscures light from these star clusters. This image is a combination of light seen in the visible and infrared parts of the electromagnetic spectrum. Multi-wavelength imaging of the color and brightness of stars helps determine their age and in turn age of the parent star cluster.
Credit: ESA/Hubble & NASA, R. Cohen
Credit Link
Glossary Terms:
Cluster , Globular Cluster , Star Cluster
Categories:
Stars
License: Public Domain Public Domain icons
File
( image
403.47 kB)
A gravitational lens magnifies one of the first stars
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Caption: This image zooms in on a star formed within the first billion years after the birth of the Universe (at a redshift of 6.2). The Hubble Space Telescope detected this light using a technique called gravitational lensing. A massive galaxy cluster between the observer and the imaged star creates a distorted and warped image of the parent galaxy and reveals its features.
Credit: NASA, ESA, B. Welch (JHU), D. Coe (STScI), A. Pagan (STScI)
Credit Link
Glossary Terms:
Gravitational Lens , Star
Categories:
Cosmology
, Stars
License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons
File
( image
6.12 MB)
Herschel’s view of new stars and molecular clouds
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Caption: This image shows the Westerhout 3, 4 and 5 star formation regions. This area has huge amounts of gas and dust. This gas and dust hides the physical processes going on in this region from studies using visible light. This image was taken in infrared light by the Herschel Space Observatory. This infrared light allowed Herschel to see deep into these star forming regions.
In Westerhout 3, 4 and 5, huge, cold clouds of molecular hydrogen have collapsed into dense knots and filaments. Within these new structures the gas is dense and cold enough for it to collapse and form stars. These new stars give off powerful winds of charged particles, like stronger versions of the solar wind our sun gives off. These winds have combined to blow massive bubbles in the surrounding gas and dust. These are visible as the large darker voids in the image.
Credit: ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech)
Credit Link
Glossary Terms:
Infrared Astronomy , Star Formation , Interstellar Medium , Molecular Cloud , Stellar Wind
Categories:
Milky Way and Interstellar Medium
, Stars
License: Creative Commons Attribution 3.0 IGO Creative Commons Attribution 3.0 IGO icons
File
( image
4.53 MB)
