JSC (AV) - Skylab 4 - TV 77-3 - General Purpose IVA Telecast / Drawing of Comet Explained - TV 107 Part 1

Description

FR A220 SKYLAB 4 KINESCOPE TAPE 8, PART 2 of 3 Okay, this is the voice for the comet description for the day. Get myself situated here...and get your notes out, let's see here I want to talk about two things today regarding the comet. First a review and a description of the comet, and secondly, to describe some of the observing techniques we've used onboard here to explain why it is we refer to certain terms of reference, like the comet seems to be SO many degrees long instead of so many miles long. First, from the general appearance, it's very similar to its appearance yester- day, if you will notice here, we've tried to indicate that there is a sort of a bright area here in the region of the coma which is the darkest spot which appears here on the drawing, Of course, that's the lightest spot in the comet as we see it in a night sky, and that there is a more or less subsidiary brightening just behind the coma represented by these more or less electrical (elliptical?) half circles or lines here. And, that the comet then takes on the more or less tail-like appearance which is characteristic of the comet in identifying ...and I've indicated two areas of sheen here which will become significant a little bit later, so we still have the comet appearing as it had in the past. Right now, it appears to be entirely white, which by stretching your imagination a little bit, you may be able to see a little bit of yellow in it, but I'm not personally convinced that you can, although I get a hint of it occasionally. Depends on where you focus your eye. As far as the shape is concerned, we've lost the forward spike almost certainly. We do not see any- thing out in front of the coma. If we look over out in front of the coma, previously we had had a spike here, now we have shown it disappear from the drawing, and we say we no longer have a spike, nor do we have the more-or-less gossamer-like branches that we showed off between the spike and now the smallest angle between the spike and the tail. So, now we have just the bright coma and the tail. One thing that is more or less interesting to look at here is to compare the size of the comet with a more-or-less garden variety get my picture here right...okay now, we'll continue here okay pick up again here. One thing that is interesting first off faint object and we can't even A220 Page 2 see it, is why the astronomers are so interest in it, and I think that if we look at the bar chart here that I've drawn for comparison purposes here along the top here, if this moreor less represents the (garble) of the comet as we see it. It extends from the coma back to almost the Planet Venus. Now I'll talk a little bit more about how we know that in just a moment, but it still goes almost back that far, which is roughly 6 degrees, and that is, of course, the length the comet represented by this long bar, and this bar here is actually exaggerated. This represents the distance betwen the earth and themoon, SO it is about a 30 to 1 ratio. In fact, the comet here this distance here represents anywhere from about 7 to 8 million miles, or maybe 6 to 9, depending on the frame of reference you want to use, and the intensity which you wish to use to say chop the tail off and say it no longer exists but is more or less dispersed into the medium (garble) just part of the interplanetary material. Anyway, this represents approximately 8 million miles, and this is a quarter of a million miles so this is a rather large object in our solar system. It has properties which the scientists are very interested in, and the dust that's in this tail here and the gases that are generated off this (garble) provide them a lot of information regarding not only what's in the comet itself, but some very interesting things about the substance. Of course, they're using this as a scientific probe of the sun itself in some respects. Okay, so this is what we're seeing now and we are seeing that the cometary tail which extends from the coma back almost to the planet Venus, and this is representative of the planet Jupitur, and here is the star, I think, Dobbie, I'm not certain of that, I think this is (garble) and there are three stars here which are represented as they appear to you when you look out the window. Okay, now as far as observing techniques, there are a couple of things that one has to do when we have to dark-adapt, and you can do this by closing one eye prior to sunset and we get at the window where we are going to make the observation, and we dark-adapt one eye, keeping the eye open, if you want to, and then we watch the comet after sunset. Now as soon as the sun sets, you can actually acquire visually acquire the comet with the unaided eye. Now just at sunset, the comet. appears to be about this long, and ifyou will notice, I did shade differently here, and as the sun goes below the horizon, and ;you get better night-adapted, you start to pick up more and more of the tail. We look at it visually, with the unaided eye, and also with binoculars. And binoculars help us see it, they also help us estimate distances. We know how wide the field of view the binoculars provide, and by looking and seeing how much the A220 Page 3 field of view the length of the comet takes up in the view of the binoculars, we can estimate that in degrees, and this brings up a very intersting question as to why we estimate degrees instead of miles, well, of course, when you're looking at objects out in to deep space, and you don't know how far away they are, all you're doing is measuring probably distances between two lines of sight - between one star and another star. The stars may be another distance away, so it's very difficult to say one star is so many miles, so we use angular distances. We use the binoculars the same way, and we can estimate the length of the cometary tail, and of course, from the coma to the tail by seeing how much of the field of view the binoculars this takes up. Another way to estimate the length of the tail is to notice its length in relation to other nice-guy objects (night sky objects). We've already mentioned the planet Venus here which is very bright, and Jupiter, and I slightly exaggerated this. My visual cutoff this morning in looking at it was about right along in here, (garble) some of this is not quite the scale, but in any event, it was probably the half to one degree short of the planet Venus, which makes this thing around 5½ to 61/2 degrees. And this was the basis on which I based the estimate of the length of the comet and aided the comparison in relationship to distances between the earth and the moon. We're continuing to watch the comet - we will continue, of course, until we come back probably, although the more intense data gathering and data collection phase of the cometary observa- tion is drawing to a close. The comet provides the scientists with such information not only about the comet but about the sun, as we've already men- tioned, but also is thought to provide cues and clues regarding the horizon origin and basis of the solar system. Hey, Ed?

Collection

Records of the National Aeronautics and Space Administration

Series

Moving Images Relating to Documentary Stock Footage