Magnifique ...

Joli :-)

Joli :-)

La grande galaxie spirale d'Andromède (aussi connue sous le nom de M31), distante d'à peine 2,5 millions d'années-lumière, est la grande spirale la plus proche de notre propre Voie lactée. Andromède est visible à l'œil nu sous la forme d'une petite tache faible et floue, mais comme la luminosité de sa surface est si faible, les observateurs occasionnels ne peuvent pas apprécier l'étendue impressionnante de la galaxie dans le ciel de la planète Terre. Cette image composite divertissante compare la taille angulaire de la galaxie voisine à une vue céleste plus brillante et plus familière. Dans cette image, une exposition profonde d'Andromède, traçant de magnifiques amas d'étoiles bleues en bras de fer en spirale bien au-delà du noyau jaune vif, est combinée à une vue typique d'une lune presque pleine. Montrée à la même échelle angulaire, la Lune couvre environ 12 degrés dans le ciel, alors que la galaxie est clairement plusieurs fois plus grande. L'exposition profonde d'Andromède comprend également deux galaxies satellites lumineuses, M32 et M110 (en bas et à droite).

Sympa :-)

How massive can a normal star be? Estimates made from distance, brightness and standard solar models had given one star in the open cluster Pismis 24 over 200 times the mass of our Sun, making it one of the most massive stars known. This star is the brightest object located just above the gas front in the featured image. Close inspection of images taken with the Hubble Space Telescope, however, have shown that Pismis 24-1 derives its brilliant luminosity not from a single star but from three at least. Component stars would still remain near 100 solar masses, making them among the more massive stars currently on record. Toward the bottom of the image, stars are still forming in the associated emission nebula NGC 6357. Appearing perhaps like a Gothic cathedral, energetic stars near the center appear to be breaking out and illuminating a spectacular cocoon.

How come the crescent Moon doesn't look like this? For one reason, because your eyes can't simultaneously discern bright and dark regions like this. Called earthshine or the da Vinci glow, the unlit part of a crescent Moon is visible but usually hard to see because it is much dimmer than the sunlit arc. In our digital age, however, the differences in brightness can be artificially reduced. The featured image is actually a digital composite of 15 short exposures of the bright crescent, and 14 longer exposures of the dim remainder. The origin of the da Vinci glow, as explained by Leonardo da Vinci about 510 years ago, is sunlight reflected first by the Earth to the Moon, and then back from the Moon to the Earth.

What would it look like to circle a black hole? If the black hole was surrounded by a swirling disk of glowing and accreting gas, then the great gravity of the black hole would deflect light emitted by the disk to make it look very unusual. The featured animated video gives a visualization. The video starts with you, the observer, looking toward the black hole from just above the plane of the accretion disk. Surrounding the central black hole is a thin circular image of the orbiting disk that marks the position of the photon sphere -- inside of which lies the black hole's event horizon. Toward the left, parts of the large main image of the disk appear brighter as they move toward you. As the video continues, you loop over the black hole, soon looking down from the top, then passing through the disk plane on the far side, then returning to your original vantage point. The accretion disk does some interesting image inversions -- but never appears flat. Visualizations such as this are particularly relevant today as black holes are being imaged in unprecedented detail by the Event Horizon Telescope.