Astronomy
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ASTRONOMIE
Trois cycles peuvent servir de référence : la rotation de la terre sur elle-même, la révolution de la lune autour de la terre, la révolution de la terre autour du soleil. Les astronomes disposent d'un bon nombre de vocables pour parler de cette période de 24 heures : jour sidéral, jour stellaire, jour solaire vrai, jour solaire moyen. Ils diffèrent en longueur. Les astronomes utilisent surtout le jour sidéral qui a une durée de 23 h 56 min 4,09 sMercury begins this month retrograding in the constellation of Pisces. On the 4th, Mercury will appear stationary against the background stars after which it will begin it's normal west to east motion across the background stars. Between the 22nd and 28th Mercury will be in the top right hand corner of the constellation Cetus before passing back into Pisces where it ends the month. On the 18th Mercury reaches its greatest western elongation of 27 o and is at the furthest from the Sun for this apparition. Mercury will, however, be low down in the mornings sky and not at its best for viewing.
Free Monthly Sky Map
This page, updated monthly, will let you know some of the things that you can look out for in the night sky. It lists the phases of the Moon, where you will see the naked-eye planets and describes some of the prominent constellations in the night sky during the month. Cassini Image of Saturn Saturn is now rising in the southern sky during the evening and will lie due south around midnight (UT) when at opposition on April 15th. It lies in the constellation Virgo close to the its brightest star Spica. The rings are now ~14 degrees from the line of site and so Saturn appears brighter than for a couple of years, but it will not be until 2018 that they will be at their widest again.
The Night Sky May 2011 | Jodrell Bank Centre for Astrophysics
Immerse yourself in a seamless beautiful environment. From web to desktop to full dome planetarium, WorldWide Telescope (WWT) enables you to explore the universe, bringing together imagery from the best ground and space-based telescopes in the world and combining it with 3D navigation. Experience narrated guided tours from astronomers and educators featuring interesting places in the sky.
WorldWide Telescope
This document contains all the controls in the Your Sky Horizon View control panel, with an explanation of the function of each. The controls in this document are “live”—you're free to experiment with various settings, pressing the “Update” button at the top or bottom of the page to display a horizon view with the settings you've chosen.
Your Sky: Horizon View Control Panel
NASA
The Juno spacecraft will, for the first time, see below Jupiter's dense clouds. Voyager 1 and 2 took advantage of a rare planetary alignment to conduct a historic tour of the outer solar system and build enough velocity to...
This Week's Sky at a Glance
The bright Moon rises around the end of twilight below Saturn and Spica in the east-southeast. Later in the evening the three shine higher: a long, narrow triangle with the Moon at the bottom. Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.
Calcul des ephémérides
Depuis plusieurs années, l'Observatoire de Paris et l'IMCCE, publient cet agenda astronomique unique en son genre. Découvrez le ciel jusqu'à ces lointaines galaxies aux mille couleurs, abordez les progrès scientifiques qui ont permis de dévoiler les mystères de l'Univers, retrouvez ces hommes et ces femmes qui ont repoussé les limites de la connaissance ! Vous découvrirez aussi cette année les dernières avancées en matière de radioastronomie. Pourquoi un observatoire de la marine à Paris, au parc Montsouris?An ephemeris (plural: ephemerides; from the Greek word ἐφημέριος ephemerios "daily") is a table of values that gives the positions of astronomical objects in the sky at a given time or times. by May 28
T he Moon, the Sun, and three of the five naked-eye planets always put on great shows through telescopes. All are so bright that they punch right through light pollution, haze, and smog as if those problems weren't even there. That's why many urban astronomers prefer to stick close to home when stargazing. But all is not necessarily paradise in metropolis. Even though light pollution may not impact planetary observing, concrete jungles can be full of localized sources of heat, which lead to turbulent seeing conditions and blurry views.
Observing the bright stuff - Astronomy Magazine