The dome of the sky - nice to meet you

Knowing the sky for beginners * Amir Gur, a journalist and photographer above and below the water, also developed a rotating sky map, which anyone can print for themselves and put together at home (download from the attached link)

Knowing the sky is an exciting hobby. You need patience and it's important to have a basic curiosity to understand what's really going on up there, but when you know - it feels like we have 3000 new friends, and another 3000 are waiting for us in the southern hemisphere.

As you may have already guessed, although there are probably an infinity squared of a trillion of them in the entire universe, a total of about 6000 stars can be seen from Earth with the naked eye. True - there is no chance that we will see them all and except for a few among us for whom astronomy is a lifelong pursuit, there is also not much chance that we will know more than a few dozen. But to enjoy the night sky it is enough as a start. Almost all ancient peoples and cultures were interested in the sky and studied it. Those ancients, and especially the Greeks and the Arabs, divided the stars for us into about 80 known constellations.

The association of several stars in one group is nothing more than eye catching, since in space they can be very far from each other, and lack any connection between them. But for the observer looking from the earth, for those ancient peoples and also for us today, stars belonging to a certain group will appear to be close to each other and create an aerial shape, which with a lot of imagination you can perhaps associate a mythological figure or a monster from the folklore of the peoples. So when you sit at night on the dark deck (or alternatively in the heart of the desert), without beach lights and preferably without the moonlight, which in other circumstances can be charming in itself, the simplest thing is to look for groups of stars. Each group has a brightest (strongest) star called the "alpha" of that group, and the second brightest, probably called its "beta", and so on according to the Greek alphabet.

It is very easy, then, to choose a bright star in the sky, which is probably the alpha of a certain group, and start to identify yourself according to it on the map of the sky that you have come to know. Please note that among the fixed sky map, which (in our country) consists of all those 3000 stars that can be discerned from the northern hemisphere, there are also a few planets moving around them, which belong to the changing sky map. While the stars of the Sabbath (stars in English) are huge gas bodies that emit huge amounts of radiation (like the sun, our "private" star) and are at huge distances from us (with the exception of the sun of course, which is quite close in astronomical terms).

The planets are solid or gaseous masses that are not large enough to sustain processes that will lead to significant radiation and therefore they do not emit their own light but reflect the sunlight. Because of their proximity to us, they appear strong and bright and some of them (such as the planets Venus and Jupiter) are brighter than any star (again, with the exception of the Sun, obviously). Also thanks to their proximity to us, their movement in the sky can usually be distinguished at intervals of a few weeks. From here you will understand that the translation of planet to "star" is fundamentally wrong. For example, in the famous movie planet of the apes, which was translated as "the planet of the apes", the exact translation should have been "the planet of the apes" (since apes are also not monkeys, but apes). Who said you switched to a simple language?

Northern exposure

Let us return for a moment to the fixed sky, to the constellations and their bright alpha stars. The names of the north are relatively well-known and quite popular in our districts. Particularly prominent there is the star that acts as a guide for sailors - as well as those navigating on land - is of course the North Star, or Polaris (from the English word pole - pole).

The North Star is located very approximately above the Earth's North Pole point, just above the axis of rotation, and therefore it does not change its position in the sky during the night. He is in himself the alpha star of a fairly well-known but relatively difficult to distinguish group - the little wagon. The Big and Little Chariots are two constellations that orbit the North Star during the night. "When above me the carts are in constant motion" Meir Ariel sang and it is possible that the poet was referring to them. In any case, these are only part of even larger groups consisting of faint stars - Ursa Major and Ursa Minor. A bear in Greek is Arctos and from this derives the name of the North Pole country Arctica - the land of the bears - and the name of the continent from which the bears cannot be seen - Ant-Arctic. By virtue of an amusing coincidence, it turned out that white polar bears travel in the Arctic, while in Antarctica there are no bears at all. The land of bears is also the land of bears and in the land of "no bears" - there are no bears.

Each cart consists of seven stars: 4 that make up the cart and another 3 that make up the pull, the rope that pulls it. The North Star is the tip of the tzul of the small cart, while in the big cart the 2 stars farthest from the tzul continue to point directly in the direction of the North Star and are an excellent and convenient method of locating it (see diagram).

On the other side of the North Star sits Cassiopeia, known by its popular and simplistic name W due to its shape reminiscent of the English letter. The Cassiopeia also contains an easy method for finding the North Star. All that needs to be done is to draw an imaginary line between the two most distant stars in Cassiopeia and move a perpendicular to this line, which will lead us straight to the North Star (see diagram). While the North Star and the Little Chariot are always in the night sky at the latitude of the State of Israel and most of the Mediterranean Sea, the Great Chariot and Cassiopeia tend to sink beyond the horizon, but always at least one of them will hover in the sky to hint at the location of Polaris. And that's without touching (yet) the north arrow, which also contributes to the task of finding the north.

This, then, is the system of Polaris the North Star, the Chariots and Cassiopeia that surround it and point to it, each in its own way. It's not much, but enough information for the novice viewer. Whoever starts to fall in love, I hope he will continue for a long time. All that is needed, as mentioned, is to go out on a dark night, under a cloudless sky, when the moon is in full moon (or alternatively before it has risen or after it has set), with a hot thermos, a red flashlight, sky maps and most importantly a good partner (or a good partner) to enjoy the new friends up there

About the author

Amir Gur is a graduate of the navy's seamen's course, where he began to study and become interested in knowledge of the sky. To download a rotating sky map You are invited to enter his personal blog: above and below the water.