StarGazing with Jack Horkheimer
StarGazer is a production of WPBT Miami, produced in cooperation with the Miami Museum of Science and Space Transit Planetarium
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StarGazing with Jack Horkheimer is seen nationally on most PBS stations. If it is not currently on your PBS station we suggest you contact your local PBS programming director and let them know it is available free to all PBS stations. You may take any and all episodes of the program off satellite for personal use, classroom use, astronomy club use, etc. free of charge. |
SCRIPTS FOR THIS MONTH’S SHOWS
1292nd Show
To Be Aired : Monday 9/09/2002 through Sunday 9/15/2002
“The Annual Return Of The False Dawn Of Omar Khayyam And How To Find It Next Week”
Horkheimer: Greetings, greetings fellow star gazers. Almost a thousand years ago the Persian poet Omar Khayyam in his book of poetry “The Rubaiyat” wrote his most famous line ” a jug of wine, a loaf of bread and thou beside me singing in the wilderness”. Did you know that besides being a poet Omar Khayyam was also an astronomer? In fact, elsewhere in “The Rubaiyat” Omar makes a poetic allusion to a “false dawn” which can only be seen at a certain time of year. And although no one a thousand years ago could even suspect what this “false dawn” really was, we now know it to be a scientific reality. And we can not only tell you what it is, we can also tell you exactly when and where to find it. Let me show you:
O.K., if we could go way out in space and look down on our solar system with superhuman vision, we would notice a faint, almost imperceptible vast cloud extending outward from the Sun in the plane of the orbits of Mercury, Venus, Earth and slightly beyond; an enormous cloud of cosmic dust. And while one would expect it would be impossible to see this super faint cloud from Earth, nevertheless in September when the plane of our Earth’s orbit is almost vertical to the horizon, we can. And we now know it is the ‘false dawn’ Omar Khayyam wrote about.
Although the best time to see this ‘false dawn’ is every September, to see it, you absolutely must be far away from city lights when there is no moonlight to hide its faint glow, like next week. If you can see the Milky Way from where you live, then you’ll also have a good chance of seeing this rare phenomenon. Look for the ‘false dawn’ in the east, 2 hours before sunrise, and the real dawn. It will look like a wedge or cone-shaped dim patch of light about the same brightness as the Milky Way and it will extend from the horizon about half way up to the zenith about 40 degrees … an ethereal, faintly glowing, rounded pyramid of light.
Now the scientific name of this phenomenon is the zodiacal light and it’s caused by sunlight scattered from all those trillions and trillions of dust particles. Although Omar didn’t mention it, this ‘false dawn’ also has an evening counterpart; a ‘false dusk’. The evening zodiacal light, which looks pretty much the same except that it is visible 2 hours after sunset in the west in March when the plane of our Earth’s orbit is also almost vertical to the horizon. Additionally, if you ever see a similar oval-shaped glow directly overhead at midnight you could be seeing the zodiacal light’s sister phenomenon called the gegenschein or counterglow. And I personally wonder whether any poet ever wrote about that.
At any rate, remember that September is the month to see the ‘false dawn’ of Omar Khayyam, the morning zodiacal light, which I admit is very elusive. But once you’ve found it I think you’ll know why it appeared in poetry centuries before it appeared in scientific writings. So get thee outside next week before dawn and see if you can see what an ancient poet saw.
I’m Jack Horkheimer, Keep Looking Up!
Episode # 02-38
1293rd Show
To Be Aired : Monday 9/16/2002 through Sunday 9/22/2002
“Weekend Of The Harvest Moon And The Autumnal Equinox”
Horkheimer: Greetings, greetings fellow star gazers. Yes indeed, this weekend is the weekend of the fabled Harvest Moon. The full moon closest to the autumnal equinox is always called the Harvest Moon and this year the equinox occurs Sunday the 22nd and Monday morning the 23rd. The moon is officially full on Saturday the 21st.
Now the first moment of autumn (which astronomers call the autumnal equinox) for the Northern Hemisphere occurs whenever our Sun crosses the celestial equator. It is actually a specific minute in time that changes from year to year. This year the moment of the autumnal equinox is Monday September 23rd at 12:55 a.m. Eastern Daylight Time, which is actually Sunday night in other time zones.
At any rate, the full moon closest to the autumnal equinox is always called the Harvest Moon, which means that it usually occurs in September but occasionally in October. This year’s Harvest Moon occurs extremely close to the equinox because the Moon is full on September 21st. Now the reason we call the full moon closest to the equinox the Harvest Moon is that traditionally the autumn harvest took place at this time and before the invention of electric lights farmers worked after sunset under the bright light of the harvest moon bringing in their crops. Not just for one night but for several nights.
You see for all practical purposes, the harvest moon lasts for three or four nights. That’s because it rises close to sunset for three or four nights in a row. The astronomical reason for this is that the path of the full moon closest to the autumnal equinox always makes a much smaller angle with the horizon than at any other time of the year. Now whenever any full moon is close to the horizon we always look at it through thicker and dustier layers of our Earth’s atmosphere which often makes the Moon look orange as it rises. So, this weekend we may see orange moonrises several nights in a row.
Although the Harvest Moon looks like it’s much bigger when it rises than when it’s overhead, you can prove to yourself that this is only an optical illusion. How? Simple. Take a dime and hold it out at arm’s length as the Harvest Moon climbs up the horizon. You’ll see that the dime covers exactly the same amount of the Moon as it does if you hold it out at arm’s length in front of the Moon when it’s high up overhead. The reason it seems larger when it’s close to the horizon is due to the optical illusion of seeing the moon close to familiar foreground objects, such as trees and buildings. If however there are no foreground objects or if the foreground objects are totally unfamiliar or strange to you the Moon will almost magically shrink.
And you can prove it to yourself. Look up at the Harvest Moon as it rises, then turn around. And then if you bend over at the waist and look at the moon upside down between your legs, it will magically shrink because then familiar trees and buildings will be seen in a way that makes them totally unfamiliar. Believe it or not, the Moon really does look smaller when you look at it upside down than when you look at it right side up. Try it yourself this weekend on the nights of the Harvest Moon.
I’m Jack Horkheimer, Keep Looking Up!
Episode #02-39
1294th Show
To Be Aired : Monday 9/23/2002 through Sunday 9/29/2002
“Venus At Greatest Brilliancy And Two Wonderful Morning Planets”
Horkheimer: Greetings, greetings fellow star gazers. And have we ever got 3 bright planets for you. One for those of you who like to do early evening planet viewing and two for those who like to do your planet watching a bit later. Let me show you.
O.K., we’ve got our skies set up for the middle of this week, Thursday, September 26th facing almost due west where the Sun will have just set; the sun always sets due west at the time of the autumnal equinox which was last Sunday. And if you have a clear almost flat horizon and look southwest you will see Venus almost ablaze because this week it is at its greatest brilliancy. In fact, it is 17 1/2 times brighter than the brightest star, Sirius. Indeed, the only objects in the sky brighter than Venus this week will be the Moon and the Sun. But you’re going to have to look right after sunset because it is so close to the horizon.
Venus is often called our twin sister planet because it’s almost the same size as Earth, only 8,000 miles in diameter. And the reason it shines so brightly is two fold. It’s extremely close to us right now and it has the highest albedo of all the planets which means that it is the most reflective, the reason being that Venus is completely enshrouded in a perpetual cloud cover. And this cloud cover acts like a great mirror and reflects sunlight very well.
Now whenever Venus appears in evening skies it is traditionally called the ‘evening star’ even though it’s a planet. And conversely, whenever it appears in morning skies before sunrise, it’s called the ‘morning star’. It will leave our evening skies as the ‘evening star’ in about 3 weeks and won’t reappear in morning skies as the ‘morning star’ until early November. So see it now.
If you go out around midnight, Friday, the 27th and look east you’ll see a wonderful almost last quarter moon just above 75,000 mile wide Saturn. As the hours go by Saturn will rise higher and higher in the heavens and the moon will slowly glide towards it so that by midnight Saturday the 28th, the Moon will be right beside Saturn and will glide with it across the sky for the rest of the night. If you’ve got a telescope now would be the time to drag it out. Because this year Saturn is at its best since 1973 and its rings are tilted for optimum viewing.
Now if you get up with the chickens, go out an hour or so before sunrise Sunday morning and Saturn will be almost overhead and below it you’ll see the second brightest planet, 88,000 mile wide Jupiter. And you can watch the Moon get skinnier and move closer to Jupiter every day; on Monday the 30th it will be close to Castor and Pollux, the twin stars of Gemini and on Tuesday October 1st, it will be between them and Jupiter. Then ta da! on Wednesday morning the 2nd it will be parked right alongside old Jupe. Once again, Sunday, Monday, Tuesday, Wednesday. And for a bonus, on Thursday it will be parked right next to Regulus, the brightest star of Leo the lion. Remember, Venus in early evening and Saturn and Jupiter in early morning.
I’m Jack Horkheimer, Keep Looking Up!
Episode #02-40
1295th Show
To Be Aired : Monday 9/30/2002 through Sunday 10/06/2002
“Mars And Mercury Pair Up And The Rival Of Mars Says Good-Bye”
Horkheimer: Greetings, greetings fellow star gazers. Well it’s time to say farewell to the ancient rival of Mars and say hello to Mercury as it joins Mars and makes its best appearance as a morning star for 2002. Let me show you.
O.K., we’ve got our skies set up for this upcoming Tuesday October 8th, 30 minutes after sunset facing southwest where you’ll see a slender sliver of a crescent moon complete with earth shine, then on Wednesday, the 9th a slightly larger crescent will park itself right next to the 3 stars that mark the top of Scorpius and will be just to the right of Mars’ ancient rival, the star our ancestors named Antares which literally means ‘the Rival of Mars’. Antares is the heart of the scorpion and just coincidentally is a red star like a heart should be. And even more coincidentally it is a variable star that slowly pulsates and changes its size and even the hue of its color; sometimes looking very red and sometimes kind of orangeish red.
In fact, whenever Mars appears close to Antares they do look alike, thus giving visual proof to Mars’ rival namesake. But they’re similar in appearance only. In fact, few objects could be so dissimilar. Mars is a tiny 4,000 mile wide planet while Antares is a humongous star, so huge that if we could replace our Sun with Antares it would stretch out past the orbits of Mercury, Venus and Earth, even past the orbit of Mars. But next week we have to bid Antares and Scorpius farewell because they are getting ready to disappear below the horizon. After all Scorpius is a summer constellation.
Now if you look right behind Scorpius, you’ll see the teapot portion of Sagittarius now positioned in such a way that if it were full of cosmic tea, the tea would be pouring out on the scorpion’s tail. Maybe that’s why Scorpius is in such a hurry to leave so early in October. In fact only two hours after sunset, Scorpius and Antares will be gone. But if you look east about 45 minutes before sunrise, you will see Antares’ namesake, tiny 4,000 mile wide, reddish-orange Mars. And on Friday, October 4th an exquisite old crescent moon will be between Mars and Regulus, the brightest star of Leo. Plus if you’ve got a clear flat horizon you may even see tiny 3,000 mile wide Mercury make its reappearance.
Now if you watch from day to day, Mercury will rise higher and higher and get brighter and brighter. And by the 3rd week of October will be at its brightest. On Saturday, the 5th an extremely old crescent moon will be parked right alongside Mercury. And each day Mercury will rapidly move closer to Mars. In fact, on Thursday the 10th, Mercury and Mars will be at their closest, less than 3 degrees apart. So start your Mercury/ Mars watch now and see for yourself if Mercury deserves its name the pink planet.
You see, because it never gets very high above the horizon, we always see it through dirty, dense layers of Earth’s atmosphere which frequently makes Mercury look pink. So there you have it, Mercury and Mars, just before sunrise and a farewell to Mars’ rival right after sunset.
I’m Jack Horkheimer, Keep Looking Up!