NASA EDGE: Transit of Venus
Transit of Venus coverage from NASA's Infrared Telescope Facility atop Mauna Kea in Hawaii
- Koa Rice
- Gary Fujihara
- Alex Young
- Lou Mayo
- Alan Tokunaga
- Kelly Fast
- Cherilynn Morrow
- Troy Cline
- Holly Gilbert
- Andy Lunt
ANNOUNCER: It happens every 100 years; a once in a lifetime, astronomical alignment with awesome views of the planet, Venus, and the sun. From the Infrared Telescope Facility on Mauna Kea, Hawaii, NASA EDGE brings you three unique, telescopic views of the transit of Venus.[Music] [Koa chanting]
BLAIR: I want to thank Koa, in particular, right off the bat for the wonderful chant that opened the show. That’s a big part of what’s going on with this broadcast. Not only are we looking at the Venus transit, which is impressive, but a lot of what we’ve done is centered around Hawaiian culture which I understand has a lot to do with astronomy.
KOA: We, as Hawaiians, have always been astronomers. We’ve looked to the heavens for guidance. If you think about it, navigation and wave finding is with the stars and that’s what brought us here from the South Pacific originally.
BLAIR: It continues here because not only are we looking at the transit, there’s a whole complex of observatories up here.
GARY: Absolutely. The Polynesian and Hawaiians of old were explorers of their days and instruments that they had at hand at their time. Today’s explorers, of course, are astronomers on the tops of big mountains like Mauna Kea, here. They’re discovering distant galaxies and a vast universe. There are a lot of parallels here.
BLAIR: We’re up here at an area, while it looks like Mars from a NASA standpoint, obviously it has great significance for Hawaiians in general.
KOA: Mauna Kai has always been a very sacred mountain to the Hawaiian people. It is the highest point in the Pacific. We say that this is the wao akua, the realm of the gods. It’s very sacred. David Kalākaua, our last king, he actually invited astronomers to come here in 1874 for the Venus transit. They set up telescopes on Oahu, set up telescopes here at ‘lolani palace in Kailua Kona And also on the island of Kauai, in Waimea Town.
GARY: This event is a re-visitation of an event that occurred 136 years ago under the reign of one of Hawaii’s last monarchs. It offers a culture component for which many of our young people can take great pride in.
BLAIR: I think that’s great too. I hope that there is some additional break through that will allow us all to come back in 2117 to Mauna Kai and actually witness the next transit. You know? Listen, I’m rolling the dice on that one.
GARY: I don’t want to wait that long, Blair.
BLAIR: Well, I tell you what. After the show, you can take the copy of what we do here and just rerun it.
CHRIS: Lou, this has been a two-year process in the making to get ready for this event. Take us through that process.
LOU: The process started a little before 2004 when we realized, oh my god, there are going to be two Venus transits and we’re going to be around for them. So, we built the education program for the 2004 transit, had observatories from Nova Scotia down to South America looking at the transit and piping the images in. Then, about a year and half ago, we started preparing for this one. What’s so cool about this is we have so many wonderful partners around the world who are helping us out, holding transit parties, holding observing events. This is truely an international, world-wide event.
FRANKLIN: Right now, you’re taking a look at the H-alpha telescope. Throughout the show, we will be going to Calcium-K.
BLAIR: There’s another. There’s a white light filter.
CHRIS: So, we have three different views. We’re going to rotate those views throughout the 7-hour program. It’s going to be pretty stunning, isn’t it?
BLAIR: Seriously kids, if you’re out there, please don’t look at the sun. Even our cameras if they weren’t filtered properly, it would damage the cameras to look into the sun.
BLAIR: It’s serious business.
FRANKLIN: We want to remind you of how high we up…what altitude we’re at.
CHRIS: See, it’s affecting you.
FRANKLIN: It is affecting me already. We’re at 14,000 feet. We actually came up to Mauna Kai several days ago to get acclimated. But even if you’re acclimated, you can show the affects of altitude. If during the broadcast we start speaking slowly or something comes out wrong, it’s because we’re being affected by the altitude.
CHRIS: We have a special partner way up in the sky, in space, that’s taking some cool images of the sun.
ALEX: Yeah. That’s SDO or the Solar Dynamics Observatory and that’s NASA’s newest solar mission, giving us this super, high-definition view of the sun in many different wavelengths of light; incredible spatial resolutions; images are spectacular. They’ve put together a special viewing program just for the transit of Venus. They’re going to give us unprecedented views from space before it even reaches the sun, as it travels across, and then leaves the sun. We’re going to see it not only in the visible but we’re going to see it in extreme ultraviolet, which shows us the outer area called the corona, which is something very difficult to see from the ground except during a total solar eclipse.
BLAIR: As I understand it, you’re the director of NASA’s Infrared Telescope Facility, correct?
ALAN: Yes. I’ve been doing this for about 10 years now.
BLAIR: What do you do at the IRTF, if you will?
ALAN: The IRTF was built by NASA to support planetary missions. Our priority is to provide observations that are useful for NASA, for NASA’s missions, and also for planetary research.
BLAIR: It’s pretty unique to have an infrared telescope. What do you actually do with an infrared telescope, because, obviously all my astronomy work has been with amateur telescopes?
ALAN: Infrared is heat radiation. It turns out that there’s a lot of information in the infrared wavelengths that don’t exist in the visible wavelengths. Because it’s heat radiation, we can detect the amount of heat that astronomical bodies emit. We can measure temperatures of the surfaces of the satellites, planets, and other stars and even galaxies.
BLAIR: Did you pick this location on Mauna Kea because of its altitude and everything because it helped infrared observation particularly or what played into that decision?
ALAN: Yes, this telescope was built here specifically because it’s the best site in the world for infrared astronomy. High altitude means it’s very dry. We’re above a lot of the water vapor in the Earth’s atmosphere. And water vapor is the main absorber of infrared radiation. It’s very fortunate to be at high altitude. And also it’s cold. Since we’re trying to detect infrared radiation, thermal radiation, it is very important to be in a cold site.
BLAIR: Do you guys run all year or do you operate seasonally?
ALAN: We operate pretty much every night of the year. We’re one of the few observatories that welcome visitors to bring their instruments to the observatory. We can transmit their data to their home institution by the Internet. But more importantly, many of our observers observe remotely. They’ll stay at their home institution and observe with our telescope using the Internet. Actually, most people do enjoy coming out here. It’s quite an experience to be up here.
BLAIR: But it is an extreme environment. In fact, we’ve learned all about the safety precautions that you have to take here, even driving up in terms of snow, and all kinds of conditions you might encounter. But then also, operating at altitude requires a good buddy system and lots of contingencies so the observers, the scientists, and all the facility folks stay safe.
FRANKLIN: Cherilynn, some people would ask today, what’s the bid deal? Why should we care about the transit of Venus?
CHERILYNN: Oh well, the transit of Venus is one of those things that has helped us understand our place in the cosmos. You can measure the transit of Venus and do some simple trigonometry and geometry. Yes, you too can do it in school, and basically calculate the distance between the sun and Earth. That astronomical unit gave us a calibration for how far away all the other planets were.
LOU: In the early 1600s, they only knew relative distances; how many times further away things were. As soon as they got one distance measured, then they could use ratios and apply it to everything else.
CHRIS: And parallax was the method we could determine what that distance is.
LOU: That’s right. And this is the miracle of the ancients who didn’t have telescopes, didn’t have spacecrafts, they didn’t have advanced instrumentation but they had their minds. And they came up with these amazing techniques to understand the universe. We have this technique called parallax. Parallax, in just a few words, is the fact that near by objects appear to fall against their background in different places depending upon who’s looking. The best way I’ve found to demonstrate this is just to use your body, outstretch your arm and put your thumb up.
BLAIR: Okay, thumb up.
LOU: Close one eye.
BLAIR: Does it matter which one?
LOU: It doesn’t matter which one.
BLAIR: Okay, I’m going to close my right eye.
LOU: All right, that’s fine, Blair. Then look and see where your thumb falls on the background of the IRTF. Now, close that eye and open the other one.
BLAIR: Oh, wow! I’m almost covering the camera now.
LOU: Yes, your thumb appears to shift, doesn’t it?
LOU: Do it a couple of times. Make sure you know how much your thumb shifts.
BLAIR: Oh, oh, wow! Okay.
CHRIS: Yeah, it’s a big shift.
LOU: Now, move your thumb in close to your face.
LOU: Do that same thing; first one eye, than the other.
BLAIR: Oh, wow!
LOU: What do you notice?
BLAIR: The distance is greater.
LOU: It appears to move more, doesn’t it?
LOU: Okay, so now we have a qualitative method, not that you would ever use this but we have a qualitative method of telling how far away from your face your thumb is. Right?
BLAIR: I would call this an arm’s length.
LOU: It’s about an arm’s length but you don’t know, you could be anywhere in here. Now, replace your thumb though. Imagine you replace your thumb with the planet Venus.
BLAIR: Okay. Um. Hmm. All right, I see that.
LOU: Your two eyes are now two observers on the Earth space wide apart.
LOU: The background of the IRTF is the sun, the disc of the sun.
LOU: Now, we have a qualitative method of determining how far away Venus is.
BLAIR: Okay, for the purposes of illustration, you said the two eyes being two different observers on the Earth, right? Historically, that would have been those, in Hawaii, looking at it versus those in India looking at it back in the 1800s or somewhere else on the planet, that’s the two different observers or multiple observers.
LOU: That’s great expeditions to far off lands were launched in order to do that.
CHRIS: Isn’t the key though that when you have those two Earth observers, they had to be a certain distance apart? Because you don’t want to be close like we are because the angle is going to be…
LOU: The angle will be too small. So they would try to get thousands of miles apart.
BLAIR: Franklin, obviously everyone’s very excited about transit of Venus. One of the events we got to see earlier was first contact, which is really cool because that’s when Venus first crosses in front of the sun.
FRANKLIN: A very special moment indeed. You know, we love it when kids get excited but when you see adults turn into kids right in front of your eyes and get excited about the Venus transit, it turns into a very, very special moment.
KELLY: What came out of these earlier transit observations was that Venus had an atmosphere. To be able to see that ring of light around Venus as it started passing in front of the sun because of the way that Venus’s atmosphere was reflecting that light from the sun. That’s changed everything.
CHERILYNN: The other thing about the transit, this is the method that Kepler spacecraft is currently using to detect the presence of Earth and Venus size worlds because after all these worlds are about the same size. They are using a telescope, looking at the area of the sky called the summer triangle or the navigator’s triangle here on the island. They’re looking in that area of the sky at 100,000 stars to detect just this type transit, to detect the presence of Earth’s and Venus-size worlds orbiting the distant stars.
BLAIR: I’ve noticed that we’ve been getting a lot of questions from a lot of the social media folks but you’ve actually been there first hand. Have you seen a lot of new fans joining, people that you hadn’t known before, that kind of thing?
TROY: Oh, yeah. We probably have doubled the viewership on our Facebook and Twitter site already just since this morning. The questions that are coming in are just extraordinary. We write those questions down as quickly as we can, and race them out here.
BLAIR: That is an important point. A lot of people would say why not just send them to a phone or something like that? We’re operating near NASA’s Infrared Telescope Facility. We are not allowed to use cell phones up here because it interferes with the operations of the telescopes. Of course, these telescopes are all operational.
TROY: They are.
BLAIR: They’re not taking a day off for the Venus transit. Obviously, IRTF functions at night primarily, nonetheless, some of the other telescopes you see in the background, they operate and are not shutting down today. They are observing.
TROY: That’s right.
BLAIR: Things are in full swing here. So, we can’t use these new technologies here. In fact, you see here we’re on wired mics.
TROY: That’s right.
BLAIR: We usually use wireless mics.
FRANKLIN: Right now, I have the monitor here and I want to show you an image from SDO. I want you to explain to our viewers what they’re seeing.
ALEX: Okay. This is amazing. This is data in the 304 angstrom wavelength from SDO. This is showing us extreme ultraviolet light and this is very sensitive to materials in the tens of thousands of degrees. Normally, you would expect it to be a black dot but what you’re actually seeing here is light is being scattered around it. So, it’s actually got some color to it; you see not just the simple black dot. This particular wavelength of light is really important for looking at things like solar prominences, and also solar filaments.
FRANKLIN: Holly, Alex just talked about solar prominences. Can you explain a little bit about what that is?
HOLLY: Sure. They’re my favorite solar activity of all time. Solar prominences are huge masses of material that are suspended in the very hot corona which is the outer most layer of the solar atmosphere. Now, these prominences, they look like clouds but they’re very dense and relatively cool, on the order of maybe 10,000° to 80,000°. But often times, you will see them erupt, which means they fly away from the sun at very high speeds. They are associated with what we call space weather, coronal mass ejections and are also associated with flares because of the process called magnetic reconnection; not magnetospherence.[Franklin laughing]
BLAIR: We’ve talked a lot about the different spectrum telescopes that we’re using. Calcium-K, hydrogen-alpha, white light, things like that. A lot of our viewers just don’t understand what we’re meaning when we’re saying that. I know I don’t understand what we’re meaning.
LOU: We’re actually looking at the sun in different wavelengths of light.
BLAIR: What does that mean?
LOU: Okay. Light behaves as a wave and as a particle by the way. We won’t get into that, I guess.
BLAIR: That’s for another show.
LOU: Light was first understood as something that was probably a lot like sound waves. Of course, it’s a little different than sound because it doesn't need a medium to propagate through. If you drop a pebble into water, you can see the waves rippling. It’s kind of like that.
BLAIR: Okay. If we’re looking at different waves of light, Calcium-K being one wavelength and H-Alpha and white light, what is the benefit of looking at those different wavelengths?
LOU: Sure. First of all, Hydrogen-Alpha is a red wavelength. It occurs in 650 nanometers. Calcium-K is in the blue, about 390 nanometers. And as you look at different wavelengths, you’re also sensing at different levels in the sun. So, we can see a little bit different parts of the sun. The universe, in general, looks different depending on the color of the light that you look at it in. We can get a little bit different definition by looking in these different wavelength or frequency ranges.
BLAIR: Does the Earth cool any as a result of the Venus transiting the sun?
LOU: Venus appears to us in this transit to be about one thirtieth of the diameter of the sun. For the amateur astronomers and scientists watching, it’s about one arcminute in diameter. In terms of the area of the sun, that’s approximately 1/900 the area of the sun or roughly a .10%.
BLAIR: Okay. That’s interesting because I had a conversation with a super solar physicist, Holly Gilbert, about this exact same issue. She said during an eclipse, you might in regional areas sense a slight change in temperature because you’re in shadow but she went on to say because of distance and everything else we’re probably not even feeling or getting a shadow of Venus on Earth’s surface.
LOU: That’s right. Venus is so much further away, so much smaller in terms of apparent angular size and, of course, in a total solar eclipse, you’re blocking out all of the sun. Venus is only blocking out about .1%. So, it’s unlikely that we’re going to be able to measure any affect in temperature from the Venus transit.
FRANKLIN: How long does it take for the images to get to Earth?
BLAIR: Oh, that’s a great question.
FRANKLIN: Since it takes time for light to travel.
LOU: We live in an age where we know it takes light time to travel.
BLAIR: 186,000 miles/second.
LOU: You got it. Or 3 x 108 meters/second.
BLAIR: I’m sticking with standard. I can’t convert. Sorry. Sorry, Europe.
LOU: In the 1600s I think was where they finally figured that out. They use to think light was instantaneous. But the distance to the sun from the Earth is about 150 million kilometers. Venus is about, you know, .7 of that distance. Let’s call it…
BLAIR: For the record, the altitude is why we’re allowing Lou to wing it on his numbers.
LOU: We’ll just winging it here.[Franklin laughing]
LOU: It takes light about little over 8 minutes to reach the Earth, so probably something like a third of that; a little less than three minutes from Venus.
CHRIS: The questions is can the ISS see the transit?
ALEX: Absolutely. Yes. We have been posting imagery that we have received form the ISS. And it is really spectacular.
CHRIS: That person who is actually taking pictures on ISS is astronaut Don Pettit who is the first person to be on station to actually take pictures of a Venus transit. What an historical occasion for him to be up on station. He’s actually taking the pictures from the cupola.
HOLLY: That might be the only place that’s better than here.
CHRIS: Good point.
ALEX: I think that’s a good point. Yeah.
CHRIS: Can I look at the sun using binoculars if I’m using solar glasses?
ANDY: Not if you’re wearing the solar glasses and you have the binoculars in front of your face and the binoculars are not covered on the front. No. The solar film that’s used in standard solar glasses is a plastic and it’s not designed to take that kind of a heat load that the binoculars would be able to provide to it. If you have a film in front, then you’re probably okay. I still have a hard time recommending that anytime either, but definitely not on the eye piece side of the binocular.
CHRIS: Another question; this is more of a generic question that’s going to be easy to answer. How do telescope filters work and why do we need them?
ANDY: They essentially remove the light that we don’t want to go through the system.
ANDY: And only allow that light to go through the system that we’re interested in. It’s not always possible to do everything that we do there with one filter. In fact, our hydrogen and alpha telescopes have seventeen filters in them.
CHRIS: Seventeen filters? Wow.
ANDY: Seventeen filters.
CHRIS: So, seventeen pieces of glass?
ANDY: Seventeen, well, there’s less pieces of glass but some pieces of glass have one filtering coating on one side and one filtering coating on another side. More than half of those are for safety. Safety is our number one concern.
ANDY: When you get into some of the other filters, the etalon actually produces multiple center wavelengths of light in a cone kind of shape and then we have filters that kind of trim out all the bad cones. Then we have one and we trim that back even more. It’s a process to be able to get all the way through removing all the reflections and get it really where you need it.
BLAIR: Were indigenous, Mesoamerican astronomers aware of the transit of Venus?
CHERILYNN: Certainly. The Mayans were some of the most incredible ancient observers of Venus. Their calendar is so, so precise, even by modern standards. It’s interesting, you know, that the Venus transit marks the end their latest calendar. The Mayans were really exceptional Venus observers.
BLAIR: I know so little about the scientific side of things. I’m learning all the time here. I thought this was a great question. Are Venus and the sun rotating in the same direction?
CHERILYNN: The sun actually does rotate on average it’s 28, or 30 days. It rotates more rapidly near the equator than the poles. So, it’s rotating in the same sense that most of the planets in the system rotate. But Venus, for some mysterious reason that is really not understood rotates what we call retrograde or backwards relative to the other planets in the solar system. All of the other planets; well, Uranus is tipped on its side, okay? That’s a little funky too.
BLAIR: Isn’t Venus saying why are all the other planets rotating in the wrong direction?
KELLY: It’s all relative.
CHERILYNN: And again, Venus’s day, it’s rotational period is longer than it’s orbital period.
BLAIR: My question…the first thought I had when I even heard this question was if they do rotate in different directions, what kind of impact does that have on Venus as a planet and maybe its role in the solar system?
CHERILYNN: It’s interesting you said impact. Why does Venus do this? Because, of course, the nebula out of gas and dust out of which the whole solar system formed gave us a sense of which way things ought to be rotating. But probably some form of an impact in the early solar system created this. Of course, yes, that slow rotation does change the atmospheric dynamics a lot.
CHERILYNN: You heard earlier in the show that there is a level of the atmosphere of Venus that super rotates, 60 times faster than the surface of Venus.
CHERILYNN: It’s incredible and that’s a mystery. Dynamists do not understand why that is yet.
BLAIR: It’s just funny how the characteristics of a planet and then an event like a transit actually come together to make up a perfect storm scenario of information for us as observers.
CHERILYNN: You know Blair, the perfect coincidence that the angular size of the moon matches the angular size of the sun and that the Venus transit conspires the orbital geometry and everything so that it’s a day’s event. It’s six hours. We can enjoy this and do a webcast of this nature and celebrate Venus.
FRANKLIN: We had a wonderful time learning from some of NASA’s best astro and solar physicists, educators, as well as many other contributors that joined us on the show. The last Venus transit of our generation has passed but the memory of this special day will live forever in this ground breaking broadcast from Mauna Kea. Thanks for joining us on NASA EDGE Transit of Venus.