Stellar charts for the Earth Hour 2020, Saturday, March 28, 21 h of local time (may be summertime for some southern latitudes)

The crescent Moon and Venus will be close together over west horizon, visible short after sunset already. Apart from the crescent, the rest of Moon will become apparent as twilight proceeds – illuminated by our Earth. (Thursday and Friday before, the crescent being slimmer, this phenomenon might be even more apparent, but not so hight in the sky, however.)

During the evening, you can notice how the stars travel in the sky. Moon moves more slowly than Venus and fixed stars, each hour it lags its own diameter, 1/2 degree. As night approaches, Pleiades star cluster ("Seven sisters" etc.) becomes visible just a bit above Moon and Venus.

Another phenomenon worth noticing is the still dimmed Betelgeuse, the orange-tinted armpit of Orion. It was dimming from November to February, now it's returning to its usual brightness resembling the whitish Rigel, the Orion's leg.

In the all-sky maps and those centered on Aldebaran in Taurus, ecliptics is marked. Venus is a bit north from it, Moon south. Under unpolluted sky and transparent air, it might be possible to notice the zodiacal light, when the twilight is deep enough. A cone of brighter sky going along ecliptics from horizon toward Venus and Moon. This is solar light dispersed on dust around the plane of our Solar system.

A set of maps CMa (Canis Major) is centered on Sirius, the brightest fixed star (and one of the nearest to us). It might be nice to observe how it, unlike Venus, twinkels. There is so much light from it that it produces flashes with vivid colours. Actually, each eye gets those changes independenly. If you look to proximity (converge your sight, like to a finger on a stretched arm) to see the star twice, creating a "double star" this way, each of the two images twinkles individually, uncorellated with the other.

Still another way of observing this phenomenon – scintillation – caused by the turbulence of our atmosphere when observing a distant point-like source, is using a pair of binoculars or a telescope. If you wiggle it slightly, you can resolve quick time changes into a colourful light path across the field of view. And if you defocuse the instrument enough, so that the star becomes a disk? That disk, this is actually the illuminated aperture of your telescope (a lens or a mirror). Colour patches will be moving on it. And you can cast a shadow by your fingers, putting your open hand before the telescope into the path of the Sirius light. (Of course, any bright fixed star low in the sky, so that we observe it through a lot of air, is good for that. Like Rigel or, for southern latitudes, Canopus.)

And last, a telescope will resolve Venus into a half-moon (it will become a crescent till May, as it approaches Earth and is illuminated by the Sun from the rear side). Pleiades are wonderful, as is the Sword of Orion (the short column of stars below his 3-star waist): the middle "star" (a group of stars, when magnified) in the Sword is surrounded by the mangificient Orion Nebula.
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[PARENTDIR]Parent Directory  -  
[DIR]A/2020-03-21 13:40 - All-sky maps for different latitudes
[DIR]CMa/2020-03-20 22:01 -  
[DIR]CZ-latitude50/2020-03-21 20:00 - symlinks for latitude 50, Czech advice
[DIR]Gem/2020-03-21 13:43 -  
[DIR]Ori/2020-03-20 21:59 -  
[DIR]Tau/2020-03-20 21:59 -  

The maps have been created similarly to the whole series for Globe at Night. They are made for various amounts of light pollution of the sky. The level of pollution can be guessed from how many stars are visible. The fainter a star is, the more "magnitudes" it has; the threshold values are given in maps.

Moon position is not for a local time, but for 21 h of central European time, i.e. for 20:00 UTC. So Japan will see the Moon more toward right along the ecliptics, Alaska will it have quite a lot to the left.

Jeník Hollan, CzechGlobe