Astronomy Israel: January 2018

Wednesday, January 31, 2018

A Very Special Tu B'Shevat on January 31, 2018

Tu B'Shevat is known as the "Birthday of the Trees". The name is simply the Hebrew date, the 15th of the month of Shevat, which usually falls in late January or early February. It is the date from which the age of trees is counted for purposes of taking tithes during Temple times or the age of a tree of purposes off eating its fruit. The Torah forbids eating the fruit of a tree until it is 4 years old ("Orlah"). How do we know how old a tree is? We start counting from Tu B'Shevat. That's why it's called the "Birthday of Trees". So, for halachic purposes, a tree planed one day before Tu B'Shevat becomes 1 year old on that day. And another year old on each successive Tu B'Shevat.

This year's TuB'Shevat is extra special because it corresponds to the triple astronomical whamy of a Super-Blue-Blood-Moon. (http://www.astronomyisrael.com/2018/01/super-blue-blood-moon-on-january-31-2018.html) The last time this triple astronomical whamy happened was in 1866. I have no idea when it also last coincided with TuB'Shevat!

But you may be asking yourself why TuB'shevat was picked for the birthday of the trees. Why not another date? And the answer, perhaps not surprisingly, is astronomical. TuB'Shevat is the birthday of the trees because it is a lunar, cross-quarter day. That is, it marks the cross over the middle of the winter quarter. It is half-way between the winter solstice on December 21 and the Spring equinox of March 20. So, half the winter is behind us on this day, and we start looking forward to the coming of spring. And because of this, in the temperate climate of Israel, and other similar climates, the trees beging to set their first flowers. Of course, the Jewish calendar being a lunar calendar, this is marked by a lunar event, the full moon of Shevat, which occurs on the 15th of the month, hence the Hebrew letters tet-vav (pronounced tu [two]), whose numerical value is 15. That TuB'shevat falls this year on a Super-Blue-Blood-Moon night is extra special. In fact TuB'shevat ends this year as the supermoon rises over Israel at 5:18PM in Jerusalem. I'm sure those versed in Kabbalh, Zohar, Chasidus, and astrology can tell you exactly what this means in each of those traditions, although I cannot.

Many folk cultures celebrate this cross-quarter day, but in the solar calendar, not the lunar calendar. Do you know what day that is? That's right - it's Groundhog Day (February 2) in the United States. That's the day Puxtahawney Phil emerges from his burrow and lets the world know if winter is over or if there will be another 6 weeks of winter. Why 6 weeks? Because it's half of 12 weeks (or half the winter season behind, half ahead), with just another 6 weeks to go until the Spring Equinox. It's the solar cross quarter day. It derives from the German Candelmas Day, which like many Christian traditions, derives from the Jewish TuB'Shevat.

So, the next time Groundhog Day rolls around, just remember it's the way the rest of the world celebrates TuB'shevat.

http://www.chabad.org/library/article_cdo/aid/3264/jewish/15-Shevat.htm

Sunday, January 21, 2018

Super Blue Blood Moon of Tu B'Shevat on January 31, 2018

There are alot of things, alot of colors going on here. Let's talk about what you're actually going to see.

In Israel, you are just going to see a full moon. It won't be blue; it won't be a blood red color. But because this full moon occurs when the moon is closest to earth in its orbit it will be bigger and brighter than usual, hence the term "supermoon". A supermoon is only 10%-15% bigger than a regular full moon but up to 30% brighter. Most experts will tell you that you can't see the difference unless you compare a supermoon in the sky to a regular full moon, which of course you can't do. But almost everyone, including me, who sees a supermoon feels it is much bigger than the last full moon they saw. Since a rising full moon looks bigger than usual when it's near the horizon anyway (called the "moon illusion"), most people strive to see a supermoon at moon rise to enhance the effect even more. A full moon always rises at sunset since it is opposite the sun (that's why it's full). In Israel this will be around 5:18pm on Wednesday, January 31, although the actual time will probably be anywhere from 15-30 minutes later since most people don't have a clear flat eastern horizon. Did I mention the moon will rise in the east, like all celestial bodies (you did know that, right?) So, you will need a clear eastern horizon. The full, supermoon will be in the sky all night long, you won't just see it at moon rise, but it will look biggest and brightest at moon rise due to the aforementioned "moon illusion".

Since this is the second full moon of January, it's called a "blue moon", although it never looks blue. The second full moon of a calendar month is called a "blue moon". The first one of this January was on January 1. It has come to refer to any event that occurs rarely, as a second full moon in a month is a relatively rare event. It occurs on average about every 2.72 years.

Now for the "blood moon". A blood moon is the name given to a moon in full eclipse, as it tends to look reddish during totality. This is because the earth acts like a lens and bends sunlight around itself to strike the moon during totality. This small amount of sunlight is filtered through the earth's atmosphere which makes the residual light falling on the moon red, just as the sun itself is reddened by the earth's atmosphere when it sets. You actually do see a reddish or "blood moon" during a total lunar eclipse, but sad to say, you won't in Israel, at least not this time. That's because totality ends before moon rise in Israel. You'll just see a regular, full, supermoon. No colors this time. Sorry. If you want o see the lunar eclipse on Wednesday you'll need to watch online. See the links below.

The best place for most of our readers to see the total lunar eclipse is in the wetern US. See times below. As you can see, the eclipse begins early in the morning on the east coast of the US with the moon setting in the west. It should make for a great photo opportunity! The west coast will get to see the entire even with totality beginning on the west coast at 4:52AM PST, again with the moon setting in the west.

Lunar eclipse times in the US on the morning of January 31, 2018

This is the first triple-header event since 1866: A super, blue blood moon. But wait! It gets better than that because this triple-header coincides this year with Tu B'Shevat, the 15th day of the Hebrew month of Shevat, known as the Birthday of Trees. It's the day that the age of trees is calculated from biblically for purposes of bringing tithes and offerings to the Temple and allowability to eat its fruits. (Fruits of tress are biblically prohibited until they are 4 years old, called "Orlah".) Of course, since it's the 15th of the month, it always coincides with a full moon, but I have no idea (and have not seen anyone else who does) when the last time Tu B'Shevat coincided with a super, blue, blood moon!

Unfortunately, the total lunar eclipse part of this event will not be visible in Israel. The western US will be the best place to see the lunar eclipse. (See above)

http://www.jewishpress.com/news/religion/get-ready-for-wednesdays-once-in-150-years-blood-moon-thats-also-super-moon-blue-moon-lunar-eclipse-and-tu-bshvat/2018/01/28/

NASA webcast of total lunar eclipse:
https://www.nasa.gov/press-release/nasa-television-to-air-live-coverage-of-upcoming-rare-lunar-eclipse

Other sites to watch the lunar eclipse online:
http://www.skyandtelescope.com/astronomy-news/where-to-watch-lunar-eclipse-online/

Meteor Shower Guide for 2018

http://earthsky.org/astronomy-essentials/earthskys-meteor-shower-guide

Wednesday, January 3, 2018

Quadrantid's Meteor Shower Peaks January 3-4

The first meteor shower of 2018, the Quadrantid's, peaks on the night of January 3 and the early morning of January 4. The peak is predicted for midnight, Israel Standard Time (IST). Unfortunately a nearly full moon will be in the sky all night and spoil the fun for all but the brightest members of the shower. If you're going to try viewing it just find a dark location and look up. No optical aid is required or even desirable. Just your own two eyes. Forecast rates for the peak are 11 meteors per hour, but on good years I have seen many more. This full moon of January 1-2 was the full Wolf Moon of winter, a supermoon, occurring during the moon's closest approach to earth, hence bigger and brighter than a regular full moon. Its light blocks out many meteors during peak shower nights. If you go out, stay warm!