Saturn

Many observers consider Saturn to be the most spectacular planet. Its magnificent rings, seen clearly with even small telescopes, provides Saturn a great for over other planets such as Jupiter with its clouds or Mars and its surface features. Saturn is the sixth planet in the solar system and is the furthest away from the sun that we can see with the naked eye.
For the ancients, Saturn was the seventh and last planet. The list included the sun and moon as planets and the Earth was not included. Uranus, though may be seen with the unaided eye was not considered to be a planet in ancient times since it is too faint and moves very slowly. For these reasons Saturn had the honor to be the last planet.
Saturn's movement is slow, completing its orbit around the sun every 30 years. To see Saturn movement in the sky you should watch it every two weeks. At this duration its movement will be noticeable. Currently (May 2012) Saturn is in Virgo near the bright star Spica. Using Spica as a reference fixed star will help to identify the slight movement of Saturn. Saturn is the second largest planet, however its mass is not high (relatively) and its density is only 0.7 (g/cm²) which means that Saturn will float in a very (very) big ocean just like wood.


General information on Saturn (from Wikipedia)

Saturn information
Saturn orbit
Mean distance from sun	1,426,725,413 km (9.537,070,32 AU)
Orbit time	10,832.327 days (29.657296 years)
Axis tilt	2.488°
Number of moons	60 and some more which are not named yet
Physical attributes
Radius	60,268 Km
Surface area:	‎4.27×1010‎ Sq. KM
Mass:	‎5.6846×1026‎ Kg
Density:	0.6873 g/cm2
Gravity:	8.96 m/sec2, or 0.914 g
Rotation period:	10 hours, 47 minutes, 6 second
Rotation speed:	9.87 Km/Sec (Equator)
Rotation Axis tilt:	26.73°
Escape velocity:	35.49 Km/sec
Atmosphere
Pressure:	140 K Pascal
Hydrogen	More than-93%
Helium	More than-5%
Methane	0.2%
Water vapor	0.1%
Ammonia	0.01%
Ethane	0.0005%

Saturn was one of the planets that Galileo watched with his telescope in 1610. Galileo's telescope was not sharp enough and Galileo did not see the rings very well. Galileo saw something like two ears, and that is how he draw it.

Saturn in a draw by Galileo

After some years the ears (rings) disappeared and then re-appeared. The reason for this is that the rings plane was parallel to the earth and although the rings are large, there thickness (height) is just about 10 meters. Look from a distance on a sheet of paper with its narrow thin edge toward you, and you will hardly see it. Turn the paper toward you and you will see it clearly. It is the same with the rings which becomes invisible when they face exactly toward earth. The cycle of the rings plane movement is 14 years. After some years Galileo draw the rings of Saturn again, in a way which is more similar to what we usually see.

Saturn in a draw by Galileo

Only when telescopes were improved the fine details of the rings were discovered. The origin of the rings is unknown but the best theory is that an old icy moon of Saturn was crashed to millions of small pieces. The real beauty of the rings was discovered only when Pioneer and then Voyager came close enough to Saturn during the late seventies and early eighties.

Saturn from Pioneer 11. Credit: NASA

Voyager images were much better. The next photo from Voyager 2 taken 21 Million KM from Saturn and shows 3 of its moons.

Saturn from Voyager 2. Credit: Nasa

These days Cassini is orbiting Saturn sending even more amazing photos. We will dedicate Cassini a special article next week.

Sundials in Israel

Sundials were a very important mean in the past to measure and show the time. Today, sundials are regarded more as architectural and design artifacts. Most sundials contain a gnomon which is usually a rod which casts a shadow, and a table which shows the time. There are various types of sundials, simple and complex, and they can be very accurate. This article will show some examples of the many sundials that can be found around Israel.

For a tourist, one of the best places to look for sundials is the Eretz Israel Museum in Tel-Aviv. The museum has a yard with replicas of ten sundials, old and new, from several places around Israel. Also, there is a planetarium in the museum which you should visit.

Sundial - Acre

Sundial - Acre

A replica of an ancient sundial

Ancient sundial - Israel

The Curved sundial does not have a gnomon, the entire shape of the sundial is the gnomon and it casts a shadow on the curved area. Such a sundial is good only for half of the day, so there is a need for more than one (which is on the other side of the stone).

An interesting Sundial on Bat Galim beach in Haifa. Notice the different of the width between the hours in the scale.

Sundial - Haifa

A replica of a Sundial from Jaffa.

Sundial - Jaffa

 An interesting mosaic Sundial in Kfar Masaryk (Near Acre)

Sundial - Kfar Masaryk

On the western wall of the great synagogue in Petach-Tikva there are 3 sundials (All have replicas in Eretz Israel Museum). As they are on the west wall they can only be used in the second half of the day.

Sundial - Petach-Tikva synagogue

Sundial - Petach-Tikva synagogue

Sundial - Petach-Tikva synagogue

 העתקי השעונים נמצאים גם במוזיאון ארץ ישראל

Sundial - Petach-Tikva synagogue - Replica

 Also in Petach Tikva, in the Twelve Tribes park, a mosaic sundial.

Sundial - Petach Tikva - Twelve tribes park

Sundial - Petach Tikva - Twelve Tribes park

Sundial - Petach Tikva - Twelve Tribes park

 The largest sundial in Israel is in Rishon Lezion (Moshe Dayan street)

Sundial - Rishon Lezion

Sundial - Rishon Lezion

 Going north again to Shomrat (Near Acre), an impressive sundial which has an "environmental" problem... The sundial is in the shade most of the day

Sundial in Shomrat

 A rather new type of sundial is the one without a gnomon at all. You are the gnomon and you need to stand along the middle line next to the relevant date (see the dates in the third photo). These sundials have become more and more common across the world. The sundial is in Eretz Israel Museum Tel Aviv

Sundial - Eretz Israel Museum Tel Aviv

Sundial - Eretz Israel Museum Tel Aviv - When you stand on it, your shadow shows the time

Sundial - Eretz Israel Museum Tel Aviv - Notice the various lines for the dates in the year.

A most impressive park in Israel Ramat Hanadiv, is in memory of Baron Rothschild and is located near Zichron Yaakov.

Sundial in Ramat Hanadiv Zichron Yaakov

In Jerusalem there are several sundials. Here is one of them, the courtesy of Yoav Avnion

Sundial on a synagouge wall, Jerusalem: Credit: Yoav Avnion

And another famous sundial in Jerusaelm in Yafo street near Machena Yehuda market on the wall of Zoharey Chama synagouge.

Sundial on a synagogue wall, Jerusalem: Credit: Yoav Avnion

שעון שמש עם פסוק משיר השירים
בחצר בית הספר האנגליקני ברחוב הנביאים 82 בירושלים
בית הספר האנגליקני תוכנן על ידי האדריכל ברספורד פייט והוקם בשנת 1897
תמונת CC שצילם והעלה לפליקר רון אלמוג ©

A sundial near the public library in Yerucham.

Sundial in Yerucham - Sefi Shalev

A very interesting sundial in the IDF officers academy near Mitzpe Ramon. The reflection of the dial rings is the hour,

Sundial in the IDF academy - Tom Rosenfeld

My friend, Eden Orion - An astronomer and artist - Designed and built two sundials. The first sundial is in Kornit in the memory of Ben Sela. You can read about Kornit's sundial here (In hebrew) and even if you can't read Hebrew you will see many more photos there.

Sundial in Kornit. Credit: Eden Orion

Another sundial designed by Eden (Only the astronomical feature) and  artistically designed and built by Yoav Shavit is in the national park of Ramat Gan. You can see many more photos and diagrams here (Also in Hebrew but Google translate does a fair job)

Sundial in Ramat-Gan. Credit: Eden Orion

Back to Jerusalem and to a new sundial by the old city walls created by the artist Maty Grunberg. The physical design was done by Ilan Manulis

Sundial in Teddy Park, Jerusalem. Naomi Azar

Yigal Zemer, an artist, designed and built many sundials in Israel. Here are some of his sundials.

Sundial in Beit-Shean's guest house, Yigal Zemer

Sundial in Rechovot, Yigal Zemer

Sundial in Mandelbaum pass, Jerusalem. Yigal Zemer

Sundial in Raanana. Yigal Zemer

A sundial can be part of a memorial monument like this sundial in Kedumim which is part of the memorial park to lt. Yishai Shechter.

Sundial in Kedumim. Credit: Shlomi liss

On the roof of Mitzpe Ramon visitor's center there is a very accurate sundials. The center is in memory of Ilan Ramon, the first Israel Astronaut who died in the Columbia disaster (PS: Ilan choose his last name to be Ramon because he liked the area, not vice-verse)

Sundial in Mitzpe Ramon. Anna Levin.

Sundial in Mitzpe Ramon. Anna Levin.

Sundials also symbolized the value of labor, and working in the files from sunrise to sunset. This sundial in Deganya (The first Kibbutz) represent this theme, The writing says: "The day is short and the labor is vast"

Sundial in Deganya. Saar Nudel

Sundial in Deganya. Saar Nudel

A unique time-field in Givatiim. Each pole shows the correct time when the sun is aligned with it.

Sundial at Givataaim

At the cave of the Patriacrhs in hebron there are old engravings which was used for sundial.

At the cave of the Patriarchs in Hebron. Photo: Amit Mendelson

A special sundials' garden in Ashqelon by the artist Yigal Tomarkin.

Sundials in Ashqelon: Photo: Avishay Taycher

A sundial with two gnomons (I am not sure which one is correct) is located in Tel-Azekah

Sundial in Tel-Azekah

The following sundial is located in the Lido's beach Ashdod. At first, it seems as a regular clock, and at the time I was there it was cloudy.

sundial in Ashdod

This sundial is at the summit of mount Tabor. Sadly as the clock is under shade it is not operational anymore, although you can see the subtle shade of the gnomon.

Sundial in Mt. Tabor - Photo by Muki zohar

There are more sundials in Israel, large and small, old and new. I will try and add more from time to time.

Also look at the following sites for sundials all over the world, I will be happy to add more just comment or send me a note.

• Sundials on the internet
• Sundials Atlas