Astronomy Israel: Orion

Showing posts with label Orion. Show all posts

Sunday, January 11, 2015

Comet Lovejoy Now at its Brightest

Comet Lovejoy is now at its predicted brightest, magnitude 4.9, where it is forecast to remain through January 12. Magnitude is the measure of the brightness of celestial objects. Lower numbers are brighter, higher numbers are dimmer. From there it will continue to dim to magnitude 5.9 on January 22. Magnitude 6 is considered to be the dimmest object visible to the naked eye in a totally dark sky. Yet, even if you can't view it with your naked eye, and you need extremely dark skies to see a magnitude 4.9 object with your naked eye, it should still be easily visible even in small binoculars in a suburban sky throughout the month of January.

Here is another finder chart with tick marks for date and magnitude on each date. Comet Lovejoy is now moving through Taurus, and its path runs roughly parallel to the dim stars that make up Orion's shield or bow, as it is sometimes depicted. Let us know if you have any luck finding it.

Comet Lovejoy path through the constellations

Follow Comet Lovejoy as it passes through the constellations Orion and Taurus. Tick marks show its position at 0h UT on each date as well as its magnitude. Higher magnitude numbers are dimmer. It should be easily visible in suburban skies with even small binoculars.

Now all we need in Israel to have a go at it is the end of the storms that have pummeled us for the last few days and made it impossible to see anything at all in the sky.

Wednesday, February 6, 2013

The Truly Great Nebula in Orion

One of the most famous nebulae in the sky is the Great Nebula in Orion, also known by its number in Charles Messier's catalog of deep sky objects as M42. This star formation region is in the constellation Orion, also one of the best known and most easily identified constellations in the sky. Orion is prominently placed high in the south early in the February night sky, and is so filled with wonders that I could spend an entire star tour talking just about it.

The constellation of Orion rides high in the south of a mid-winter's night. The bright red star to the upper left is Betelgeuse, an old star nearing the end of its life. At the bottom right shines Rigel, the brightest star in the constellation and a young, hot blue-white star. M42, the Great Nebula in Orion, is the central, reddish object in the sword, hanging from the three stars in Orion's belt.

M42 is a stellar nursery, or star factory as the metaphor is sometimes used. A region of our galaxy where ionized Hydrogen gas and interstellar dust are collapsing to form new stars. All stars are born is such regions, including our own sun, and evenutually evolve into open clusters whose members are flung out of the cluster through interactions with the gravity of the galactic disk. So, we are all related to brother and sister stars that have since gone their own ways, every one of us.

M42 looks pinkish in photographs because the four, newly born stars in its center, called the Trapezium because of their shape, emit utraviolet light that knocks an electron off of the atoms of hydrogen gas, causing these atoms to become positively charged, or ionized. When the electron recombines with the hydrogen atom this characteristic pink glow is emitted. The color of the glow is usually not evident to the naked eye or in any but the largest telescope, since the light is not bright enough to activate our color vision. But in photographs even short ones as above, the beautiful pink hue is evident. To the naked eye or small telescope the glowing gas cloud just looks a milky white, still a magnificent view.

M42 has long been one of the most photographed and studied regions of the sky. My friend Eddie Lubat, an amateur astrophotographer in New New Jersey, recently took a photograph of the M42 region that is one of the best I have ever seen. It not only captures the beauty and subtle details of M42 itself, but also much of the surrounding area that is often omitted in pictures of the nebula.

M42 region by Edward Lubat. The M42 nebula itself is the large pinkish area in the center right. The four stars of the Trapezium are here too small to be seen individually, but their combined light is the white glow in the center of the nebula. There is a dark lane of interstellar dust separating M42 from nearby M43 to the center left. Then there is an even larger lane of interstellar dust to the left of M43, separating it from the star cluster, far left, whose light illuminates the "Running Man Nebula", the dark feature in the bright reflection nebula to the left center. Photo by Edward Lubat.

The great gas-flowing features in the area are real, caused by the infalling gas that is forming stars, the outflowing gas that is blown away by the stellar winds of the stars that have formed, and by the collisions of this gas with stationary regions of hydrogen, giving rise to bow shocks that look like bubbles. This region is about 1345 light years away and 24 light years across in the Orion-Cygnus arm of the Milky Way galaxy.

This is one of the objects we spend time viewing and studying both naked eye and in the telescopes on my star tours on cold winter evenings. Come on by and have a look!

Friday, November 2, 2012

Hunter Moon Over Mt. Nimrod

While setting up for a night of observing last week I saw this beautiful near-full moon rising over Mt. Nimrod, just outside of Mitzpe Ramon. This was the full moon of October, called the Hunter Moon by the American Indians, the full moon following the Harvest Moon of September. The Harvest Moon lights the sky for gatherers of the harvest in the fall while the Hunter Moon lights the sky for the hunters of meat needed for the coming winter.

The Hunter Moon of October rising over Mt. Nimrod

I have no idea what this little mountain is actually called, but I observe in its shadow where it shields from the light of Mitzpe Ramon and the desert wind (somewhat). The winter constellation of Orion rises over its peak at about 10:30 this time of year, with Rigel, the brightest star in the constellation, rising directly over the peak from where I observe. It is a lovely sight to behold, a brilliant blue-white star twinkling madly as it rises directly above the top of the mountain.

In Jewish star lore the hunter Orion is identified with Nimrod, the first hunter in the Bible. Thus, my decision to call it Mt. Nimrod instead of Mt. Orion, I think more appropriate for this Holy Land mountain. It is also the test site of Raphael Industries and the IDF's new field radar system, or so I have been told. Here in the lee of the mountain we are also shielded from the light pollution that comes from the test site atop it. For some reason, the testers seem to feel the need to put up klieg lights at night whenever the tests are going on. Recently, tho, they have cut back on the lights, now using a single mercury vapor light instead of a battery of sodium vapor ones. Better, but still not good enough. Light pollution is becoming a big issue in the desert and will be ever more so with plans to move 500,000 new Olim into the desert in the next 10 years.

On the night I took this picture I saw the radar system spinning for the first time. It had always been stationary in the past. Here's a little video of it at work.

Monday, February 21, 2011

How Dark Are Your Skies?

Here is an opportunity to contribute to science, have fun, and learn about your local sky conditions. The sixth Globe at Night 2011 Campaign kicks off on February 21 and lasts until March 6. In this citizen-science project contributors from around the world will estimate how dark their skies are by comparing what they see from their location with star charts that show stars at different limiting magnitudes. The constellation chosen for this campaign is Orion, one of the most prominent and brightest constellations in the winter sky. There is even a smart phone web app that allows you to compare the sky to charts you see on the screen, fill out the form on your phone, and submit the report in real time. How cool is that!

You can do this as many nights from as many locations as you please. Or just do it once and enjoy contributing to a world wide environmental science project. The Globe at Night will integrate all of the data into a map of sky brightness around the world which will be viewable from the project's web site. This should just take a few minutes a night and will give you a chance to become familiar with one of the oldest and most beautiful constellations in the heavens.

Do this project with your children or your class, if you are a teacher. Sky brightness can vary widely over a small area, so you can compile your own map of local sky brightness. You can use it to keep track of the growing threat of light pollution in your community and even use it for an action agenda to help mitigate the effects of light pollution.

And while engaged in this project, you won't have to remember to Keep on looking up!

Globe at Night reports from 2010

Thursday, January 27, 2011

Is the Earth Destined to Have Two Suns?

In one of those displays of National Enquirerdom that seems to strike all too often on the Internet, the Huffington Post wrote an article that received alot of play about the star Betelgeuse going supernova and becoming a second sun in our day time sky. After I explained the bad science behind this "popularization" to an Astronomy Israel tour group from Birthright Israel, one of the students rightly concluded, "So you will have to pick up your children from daycare tomorrow."

Betelgeuse is my favorite star in my favorite constellation, Orion. It is (sometimes) the brightest star in the constellation (it is a variable brightness star), the eighth brightest star in the sky, and one of the most massive and largest stars known. It is one of the few stars whose nature is revealed to the naked eye since it is obviously red. Well, it is "obviously" red only after I point out to our guests that stars actually have naked-eye color and I ask them what color they think Betelgeuse is. Everyone is astonished to realize that Betelgeuse is red, although the women seem to see this more quickly than the men. I then like to do a color comparison with Rigel, the young, hot, white-blue star in Orion's knee.

Betelgeuse and Rigel, the two brightest stars in the constellation Orion. Betelgeuse is an aging red supergiant. Rigel is a bright, young, hot blue-white star. Their natures are revealed even to the naked eye. (Click for full size)

Betelgeuse is what astronomers know as a red supergiant star, a massive star that is nearing the end of its life, has burnt most of its hydrogen and helium fuel in thermonuclear reactions that power it and has cooled, thereby glowing red, a condition visible to the naked eye. A star in this condition is ready to go supernova, that is blow itself to bits in one of the most massive explosions in the universe. A supernova can generate more energy and become brighter than the whole galaxy of stars that contain it, such is the power of a supernova explosion. This, apparently, was the excitement behind the Huffington Post article.

Of course, this has been know for years to astronomers, plus when we realize that "nearing the end of its life" in cosmological terms means "could happen in the next million years", there is no reason to think you will not have to pick your children up from daycare tomorrow. Indeed, even if Betelgeuse were to go supernova tomorrow (or 600 years ago, which it would have to do to go supernova tomorrow, since it is 600 light years distant) it is so far away, that it would be no brighter than the full moon in our daytime sky, and still just a point of light to our naked eye. Bright, yes, but not exactly a second sun. This could last for anywhere from a few days to a few months as the dying star collapsed to a neutron star core.

Betelgeuse, as imaged by the Hubble Telescope in 1995, would extend beyond the orbit of Jupiter if in place of our sun, consuming 75% of our solar system.

One of the more amazing things about Betelgeuse is that it is so huge that it was the first star whose stellar disk was resolved by telescopes on earth, the first such stellar disk besides our sun's ever seen. This was done using a technique called speckle interferometry in which the output of two telescopes separated by some distance is combined to create a single image of a star. In 1995 the Hubble Space Telescope was the first single telescope to reveal the disk of the star. Recently, using the Infrared Optical Telescope Array (IOTA), the disk of Betelgeuse was resolved using interferometry to reveal two hot spots.

Two hot spots are imaged on the star Betelgeuse by the IOTA.

Betelgeuse is so large that if it were in the place of our sun, its radius would extend to engulf the planet Jupiter, or much of our entire solar system.

But you're still going to have to pick up your kids from day care tomorrow. And probably for at least a few 100,000 years beyond that. Maybe even a million.

Keep on looking up!