Astronomy Israel

Monday, December 27, 2010

A Beautiful Day in the Observing Neighborhood

With so much snow and cold throughout Europe and the US, I wanted to tell you about the beautiful day we just had here. With temperatures that required short sleeves, a beautiful blue sky and yellow sun, I decided to spend part of the afternoon at our observing site on a high plateau above Mitzpe Ramon.

When I arrived the weather was perfect and the wind was calm, resulting in an eerie quiet. I looked over the rim of the machtesh, where we take visitors at night when the moon is full, and contemplated the vast wonder of the world's largest erosion crater.

Machtesh Ramon from our observing site. (Click for full size image.)

The machtesh is a geological wonder land with all sorts of geological formations that reveal themselves under different lighting conditions and angles. I saw this black hill for the first time by the light of the low winter sun's rays.

A black hill reveals itself (below center) by the winter sun's light.

I hiked a short distance along the plateau until I came to this view through a notch in the walls of the machtesh.

Machtesh Ramon from our observing site.

The other side of our observing site is lined by pine trees from a JNF forest, their trunks bent by the prevailing winds. One of the things I like the best is the quiet at our site. I thought, perhaps, I heard the whirring sound of a generator in the distance. But perhaps not. At night, there is usually no sound to be heard. Sometimes a passing military aircraft; sometimes music from Mitzpe Ramon. But usually nothing; nothing at all.

A JNF forest borders our observing site.

On the way home I found the Ibex out enjoying a day in the sun.

Ibex Picnic

Keep on looking up!

Sunday, December 26, 2010

The Cold Returns

On Thursday we hosted the Madar family from France. Both parents and older daughter spoke excellent English and translated my talks into French for their young daughter. The cold and wind returned to sweep the high plateau where we were observing, but all managed to stay out for a good two hours before capitulating to the cold.

The moon was still mostly full but that didn't interfere with my showing the major constellations and their bright stars. We also got in good views of several open star clusters, The Great Orion Nebula (M42), Jupiter (always a favorite) and its 4 Galilean moons, and, of course, the moon itself.

The Madar family from France.

Keep on looking up!

We Catch a Brief Warm Spell

Pleiades (Image via Wikipedia)A brief warming trend helped us welcome our guests from Chicago this week, the Cohans. It was during the full moon of December, so the sky and surrounding desert were still quite bright. But we still managed to get a "Wow" for the Pleiades star cluster, which is a winner any time of the month, and some good views of the Double Cluster and Jupiter. The brightest of all lunar craters, Archimedes, is my favorite during full moon, since it is an interesting shape and so much brighter than any other area through a telescope during full moon.

We were out long enough to watch the Big Dipper rise out of the horizon muck, it is not circumpolar from latitude 30 degrees N, and we got a good telescopic view of the triple star Alcor and Mizar at the bend of the handle.

The Cohans from Chicago

Keep looking up!

Wednesday, December 22, 2010

A Re-Run of Yesterday's Total Lunar Eclipse

In case weather or continent or sleep prevented you from watching yesterday's total lunar eclipse, here is a time lapse re-run done by William Castelman. Beautiful photography, but I could live without the sound track.

William Castleman's time lapse video of the total lunar eclipse of December 20-21, 2010

Notice especially the circular shape of the earth's shadow on the moon. I believe a total lunar eclipse is the only natural phenomenon where the circular shape of the earth can be directly perceived by the eye, rather than inferred from observations. This shape is especially well captured in this video. Flat Earth Society members beware!

Keep on looking up!

The Blood Red Moon of December 20-21, 2010

The colors of the eclipsed moon yesterday were generally reported as "blood red", and Jewish tradition considers the color of an eclipsed moon to be a part of its "omen" value. What causes these colors which can range from very dark and barely visible to red or copper?

The earth's shadow is considerably larger than the diameter of the moon, so when the moon passes into that shadow (called the "umbra") becoming eclipsed, it can pass through the center of the shadow or on various paths above or below the center. Generally speaking, the more centrally the moon passes through the earth's shadow, the darker and less colorful the eclipse. The various paths the moon can take through the earth's shadow also account for variations in brightness seen across the disk of the moon.

Here is the path the moon took through the earth's shadow yesterday:

Path of the moon through the earth's shadow on December 20-21, 2010

The moon passed well north of the earth's umbra, the central and darkest part of its shadow, causing the moon's northern limb to appear much brighter than the southern.

The moon at mid-eclipse. (Tony Sharfman, Cranford, NJ)

Once the moon is in the umbra, the earth's atmosphere acts as a giant lens, bending the light of the sun around the earth and focusing it on the moon. Just as at sunset the long, red rays of the sun become enhanced because the thicker atmosphere scatters all of the shorter wavelengths, most of the light striking the moon is reddened by this atmospheric scattering and lensing. This effect can be enhanced or diminished by global weather effects along the rim of the earth, so the actual colors and brightness of an eclipsed moon are impossible to predict.

And that is why we had a "blood red" eclipse yesterday.

Keep on looking up!

Does Jewish Tradition Consider Eclipses to be a Bad Omen?

It would seem from the Midrashic and Talmudic texts below that Jewish tradition considers eclipses of various kinds to be a bad omen, both for the world at large and Jews in particular, caused by our sinful behaviors and warning us to repent. Given the fact that eclipses are caused by the invariant laws of celestial mechanics, it seems rather hard to understand how our actions can influence them. Perhaps our tradition is teaching us that these events are reminders of our sinful behavior and a reminder to repair our defects. On a deeper level, perhaps in the times of Mosiach when "...the land shall be filled with the knowledge of the Lord as the waters cover the sea" (Isaiah 11) eclipses will cease or the universal light of G-dliness will blind us to them.

The eclipsed moon as seen from Teaneck, NJ on Dec. 21, 2010. (Photo credit: Yitzy Glicksman)

There is no bracha or blessing to be said upon seeing an eclipse, although it is a wonder on a par with seeing a rainbow or shooting star, for both of which there are blessings to be said. Perhaps this is because the Hebrew word for eclipse is Likui - defect. The Talmud states, as we read below, that a Likui of the sun is a bad sign for the world; a lunar Likui is a bad sign for Israel. Being associated with bad signs, the eclipse was not assigned a bracha. May one say a bracha if moved by the beauty and wonder of an eclipse? Consult with your Rav, I don't know.

I guess it's a good thing that yesterday's lunar eclipse was not visible from Israel. We dodged another bullet!

Succah 29a Our Rabbis taught, When the sun is in eclipse, it is a bad omen for the whole world. This may be illustrated by a parable. To what can this be compared? To a human being who made a banquet for his servants and put up for them a lamp. When he became wroth with them he said to his servant, ‘Take away the lamp from them, and let them sit in the dark’. It was taught: R. Meir said, Whenever the luminaries are in eclipse, it is a bad omen for Israel since they are inured to blows. This may be compared to a school teacher who comes to school with a strap in his hand. Who becomes apprehensive? He who is accustomed to be daily punished. Our Rabbis taught, When the sun is in eclipse it is a bad omen for idolaters; when the moon is in eclipse, it is a bad omen for Israel, since Israel reckons by the moon and idolaters by the sun. If it is in eclipse in the east, it is a bad omen for those who dwell in the east; if in the west, it is a bad omen for those who dwell in the west; if in the midst of heaven it is bad omen for the whole world. If its face is red as blood, [it is a sign that] the sword is coming to the world; if it is like sack-cloth, the arrows of famine are coming to the world; if it resembles both, the sword and the arrows of famine are coming to the world. If the eclipse is at sunset calamity will tarry in its coming; if at dawn, it hastens on its way: but some say the order is to be reversed. And there is no nation which is smitten that its gods are not smitten together with it, as it is said, And against all the gods of Egypt I will execute judgments. But when Israel fulfill the will of the Omnipresent, they need have no fear of all these [omens] as it is said, Thus saith the HaShem,' Learn not the way of the nations, and be not dismayed at the signs of heaven, for the nations are dismayed at them, the idolaters will be dismayed, but Israel will not be dismayed. Our Rabbis taught, On account of four things is the sun in eclipse: On account of an Ab Beth din who died and was not mourned fittingly; on account of a betrothed maiden who cried out aloud in the city and there was none to save her; on account of sodomy, and on account of two brothers whose blood was shed at the same time. And on account of four things are the luminaries in eclipse: On account of those who perpetrate forgeries, on account of those who give false witness; on account of those who rear small cattle in the land of Israel; and on account of those who cut down good trees.

Midrash Rabbah - Leviticus XXXI:9 R. Levi said: Every day the Holy One, blessed be He, sits in judgment on the globes of the sun and the moon which are reluctant to go forth to shine upon the world. What reason do they give? People burn incense to us, people worship us. R. Justa b. Shunem said: What does the Holy One, blessed be He, do to them? He sits in judgment on them and they go forth and shine upon the world against their will. Hence it is written, Every morning doth He bring His right to light--lo ne'dar {Zeph. III, 5). What is the meaning of ’lo ne'dar’? 'It does not cease.’ But the unrighteous knoweth no shame (ib.). People are not ashamed but worship them. They see them being punished but are not ashamed.