Still Cataloging The Skies, Long After 'Planet X' Perched on a mesa just above Flagstaff is the historic Lowell Observatory, founded back in the days of the Wild West. Observatory director Jeffrey Hall talks about landmark discoveries made there, like 'Planet X'--later renamed Pluto--and the exoplanets astronomers are spotting there today.
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Still Cataloging The Skies, Long After 'Planet X'

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Still Cataloging The Skies, Long After 'Planet X'

Still Cataloging The Skies, Long After 'Planet X'

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  • <iframe src="" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
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IRA FLATOW, host: This is SCIENCE FRIDAY. I'm Ira Flatow.

What comes to mind when you think of the Wild West? Of course, dusty cowboys, miners, saloons, six guns. How about astronomy? Because back in the 1890s, the mathematician and astronomer Percival Lowell sent a scout out West, away from the city lights of the East Coast, to find the perfect spot for a new observatory. His scout started down in Tombstone, Arizona, slowly working his way up the state, and he eventually made it to Flagstaff, then just a little outpost of around 800 people, selecting a mesa above the town as the ideal place for the new Lowell Observatory.

And in the years since, they have made some remarkable discoveries at Lowell, like the Planet X, aka Pluto, and other observations that eventually led to development of the Big Bang Theory and the idea that the universe is expanding. And they're still busy discovering stuff today, still hunting for planets, but not ones in our Solar System - new exoplanets. And they're studying our sun and other stars like it and planning for a flyby of Pluto. So there's a lot to talk about, a lot of stuff going on here at the Lowell.

And here to talk about it is Jeffrey Hall, astronomer and director of the Lowell Observatory here in Flagstaff. Welcome to SCIENCE FRIDAY.

Dr. JEFFREY HALL: Good afternoon, Ira. Pleasure to be here.

FLATOW: Thank you for that tour you gave me last night.

HALL: That was fun.

FLATOW: I didn't realize how hands-on it is to work that telescope.

HALL: It is. It's a 106-year-old telescope at this point, manually operated. It's open every night for people who come to Lowell for observing, and our staff just slew it around manually.


FLATOW: It's true. And it has a frying pan on...

HALL: That's right, one of the finderscopes, they couldn't figure out what to use for a cap, so why not the director's wife's frying pan?

FLATOW: High-tech, truly high-tech stuff. Tell us - let's talk about Lowell himself. Why was he so anxious to get the telescope built?

HALL: Well, Lowell was a mathematician by training, astronomer by passion, and he had become very interested in what he thought was evidence of intelligent life on Mars, the so-called canals. And in 1894, there was a particularly favorable opposition, or a geometric alignment of Earth and Mars that made it favorable for observing. So he was pretty anxious to get away from the humid, cloudy East, and out here to the dry, barren West to found a new observatory and make those observations.

FLATOW: And so he chose Flagstaff because?

HALL: Well, after a long tour through the Arizona territory, it was probably some combination of, fortunately, clear skies when his scout, Mr. Douglass, was here, good treatment by the locals and willingness to give the observatory a site of land upon what was called Site 11, and where we still are 117 years later, just about a mile from here.

FLATOW: Yeah. Let's talk about Pluto being discovered here at Lowell. Tell us the story behind that.

HALL: Well, Percival Lowell was convinced there was Planet X out beyond Neptune, which he believed was the - because of irregularities in the motions of Uranus and Neptune. It turns out that wasn't the case. But, in fact, when the Pluto search was resumed in earnest - quite some time after Lowell's death, in fact - it was found, fortuitously, fairly close to where he predicted it would be in 1930.

FLATOW: Wow. And one of the things he was involved with while he was alive was the observations of so-called spiral nebulae galaxies, right?

HALL: Well, yes. And, you know, we're certainly most famous for the discovery of Pluto, but, really, the much more profound astronomical discovery is just that. Back in 1912, we had only the most rudimentary idea of what might be beyond our Solar System and the structure of the universe, the idea that spiral nebulae might be other - well, they picturesquely called them island universes, perhaps systems of spinning stars out beyond our own galaxy. But it was speculation.

Lowell directed one of the observatory's astronomers, Vesto Slipher, to make observations of these, using that telescope you looked through last night with a spectrograph attached to it. And he found that the spectral lines in these spiral nebulae were all redshifted, and these were the first cosmological redshifts. At the time, they didn't know what they were looking at, but they were the first observations that ultimately led to the idea that the universe is expanding. It's one of the fundamental observations of the 20th century.

FLATOW: And that's what Edwin Hubble ran with, right...

HALL: Mm-hmm.

FLATOW: talk about the redshift and expansion of universe.

HALL: Right. Then developed into the expanding universe cosmology.

FLATOW: So this is - this - Edwin Hubble is one of the founders of this theory. How many times did he come up to Lowell to take a look?


HALL: Slipher's work was picked up by the folks over in California.

FLATOW: They never came here.

HALL: Not that I know of.

FLATOW: And still credited with that incredible discovery about the - using the data that came from here.

HALL: Well, as with many discoveries like this, it's a lengthy process with - we still see this today. You have discoveries where knowledge is an incremental process, and it often takes a team or a group of people to eventually come to the right answer.

FLATOW: If you'd like to ask a question, our microphones are open here in the hall. Don't be afraid to step up and ask. And would you say that that was probably the most famous use of the telescope, in the long-term, with these observations?

HALL: The Clark Telescope has been used for a number of things. Today, it's for public viewing. It was not, in fact, the telescope used to discover Pluto. That's a different one, more optimized for wide-field surveys. But certainly, with the Clark, that's pretty fundamental.

FLATOW: Did they have any idea at the time, when they were talking about - when Lowell was talking about the spiral nebula, we - our place in the galaxy was?

HALL: No. The development of - the understanding of our - the structure of our galaxy, the structure of the universe is within pretty much the last century.

FLATOW: Hmm. And one of the projects the observatory is involved in today is the New Horizons spacecraft. What's that about?

HALL: Well, that is an unmanned NASA spacecraft on its way to Pluto. It was launched in 2006. And one of the main criteria for this mission is the folks who launched it really didn't want to be dead by the time it got to Pluto. So...

FLATOW: I hate it when that happens. Yeah, yeah, yeah.

HALL: Yeah, I do to. So the idea is you build a very small, very light spacecraft and put it on the biggest rocket we've got and really fling it out there. So they launched it in 2006. Thirteen months later, they used the old gravitational slingshot past Jupiter, and now it is on its way to a 2015 rendezvous with Pluto. And if we can find a suitable object, they will continue on to try to get a close up image of one of the enigmatic Kuiper belt objects that populates the far reaches of the solar system.

FLATOW: And so your observatory is involved in that?

HALL: One of our astronomers, Will Grundy, is a member of the New Horizons science team. And like any of these missions, it's a large consortium of scientists from multiple institutions.

FLATOW: But Pluto is still very special here.

HALL: Oh, we love Pluto.


FLATOW: Is there any chance you get to do some research with Pluto?

HALL: Well, I think it's singularly appropriate. And, you know, what Will - if you ask Will: What are we going to find when we get to Pluto? What I've heard him say is: We don't know, but it's guaranteed to surprise us. And in that regard, it's just like the other unmanned missions. Think back to the Pioneer and the Voyager era. When we got our first close-up look at the moons of Jupiter and Saturn and Uranus, they're weird. All of them are pathological, in one way or another. So I'm sure that when we get there, we'll find something pretty interesting.

FLATOW: Speaking of pathological, let's go to the audience. No, no, no.


FLATOW: Sorry about that. Yes. First question here.

UNIDENTIFIED WOMAN: I wanted to ask about the dark skies, because I know Flagstaff is a dark-sky city. And I know that from some point outside of town, you can see the light pollution from Phoenix and other big cities. And what part has Lowell had in keeping the skies of Flagstaff dark?

HALL: We've had about a 50-year role in that, going back that far when there was first some indications that brightly lit advertising might be put in place in Flagstaff. And this started an effort, really, to work with the city and the citizens, not at them, to come up with a solution that provides safe and sensible lighting for people on the ground while preserving the beauty of the night sky - not only for astronomers but even from in Flagstaff.

We were looking last night. Just standing outside the Clark Telescope, you can look up one mile from downtown Flagstaff, and there's the Milky Way galaxy in all of its splendor. That's a good thing to have in the middle of a reasonably sized city. Chris Luginbuhl at the United States Naval Observatory has done some quantitative work on this, and I think the answer he got is that the skies in Flagstaff are about 30 percent darker than they would be in the absence of an ordinance. Other communities around Arizona have picked up the torch as it were, although that might be a lousy analogy.


HALL: And, you know, it's really a statewide effort, because astronomy is a huge industry in Arizona, $250 million a year pumped into the state economy and growing as new opportunities come in. So preservation of the quality of our skies, both for science, as well as for public enjoyment, is quite important. And Flagstaff has been an international leader in this regard.

FLATOW: Well, what did the ordinance say? You're not allowed to what, or...

HALL: There's a couple of components to it. It basically limits the lumens per acre. And then there are zones, lighting zones, where it's a little more strict in the areas closest to the observatories, and then gradually relaxes as you get a little further away.

FLATOW: Well, it certainly seems to be working...

HALL: It's working well. Yeah.

FLATOW: this city. Let's go to this gentleman here. Yes.

UNIDENTIFIED MAN: So you're talking about detecting exoplanets and the search for exoplanets. And I know it's - it has to do with detecting the dimming of stars. And I was wondering if you could talk more about the process that goes into finding an exoplanet.

HALL: Sure. We have an astronomer on our staff who's involved with the Kepler mission, which is out there staring at a region of sky in the constellation Cygnus, searching for planets. But finding exoplanets is a fairly recent development, because they're very hard to see, and they're small, faint. They tend to be washed out by the brilliant star next to them. So only recently have we developed the instrumentation that can find them. There's a couple of ways you can look for them.

You can look for mini eclipses. If you happen to have a star where the planet passes in front of the star, you get a very small dip, sort of like a solar eclipse, except it's not like the moon over the sun. It's just a little blip. That's kind of what Kepler is doing. They're looking for brightness variations in stars to detect the existence of planets. You can also do a little bit of - it's almost like the redshift work. You can look at spectral lines from the star altering or going back and forth a little bit as the planet tugs the star back and forth.

And then, one way that's very difficult to do is just try to take a picture and image it directly. We have astronomers at Lowell who have been involved with teams employing all three of those techniques. What we're finding - you know, in some ways, Ira, we're almost on a cusp very similar to where I think Slipher might have been in 1912. We had an idea that there were things out there, spiral nebulae, but we didn't know what they were, and we hadn't detected many of them because - but now, as we start to look for planets, they're everywhere. We're up to about 700 of them, wherever we look, and we're starting to get the picture of a galaxy that's just brimming with worlds.

Now, by and large, if you're really looking to get away from it all and do an exoplanet vacation, say...


HALL: ...the ones we found so far are horrible, you know, gas giant-sized, very close to their parent stars, 2,200-degree atmospheres. Ew. You can't think about it.


HALL: But missions like Kepler now have the ability and the precision to detect ever-smaller planets that are more Earthlike, and the real Holy Grail is a planet in habitable zone around a sun-like star. This is a planet where water can exist in all three of its phases and, potentially, a source for life as we know it.


I'm Ira Flatow here in Flagstaff, talking about the Lowell Observatory. And you guys also do research on the sun. Well, isn't it?

HALL: Yeah. I do.

FLATOW: And what do you want to know about the sun? What are you thinking about?

HALL: Well, we want to know if it's going to destroy us - no, no.


HALL: I came to Lowell involved in a project designed to do long-term monitoring of the solar activity cycle and similar activity cycles in stars like the sun, the idea being the sun influences terrestrial climate. We know it does weird things. The cycle seems to turn off or go into very quiescent periods from time to time. What effect might that have on terrestrial climate?

The problem is, first of all, you know, Ivo points out that a million year is chump change. We're astronomers, OK? Ten million years is chump change for us.


HALL: And by the time - by that point, I'm going to be thoroughly sick of this project.


HALL: So instead of observing one star for 10 million years, we observe a whole bunch of the most solar-like stars we can. Now, imagine - looking out at this audience, imagine understanding the human race by observing one person. You know, you'd have a very myopic view. We use other suns as proxies for our own to understand how the sun might have varied over hundreds to thousands, millions of years.

FLATOW: A question - oh, there's a familiar face. Go ahead.

HALL: Hi, Brian.

BRIAN: Hi, Jeff. Can you share with us about the capacity of the new Discovery telescope and when it's going to be working and...

HALL: Brian, I would love to share that with you.


FLATOW: We did not set this up for today.

HALL: No. This - yes.

FLATOW: I didn't. I don't know if these guys were...

BRIAN: And I honestly don't know about it.


FLATOW: Tell us this new telescope, or what it's about.

HALL: I just got back from that telescope, where I was giving some folks a tour. Astronomers do what they do by collecting light. You know, we can't go out and dig in the ground, and we can't put a star in a beaker and poke it. We collect light, and so we need light buckets. Lowell's currently largest telescope has a mirror of 1.8 meters aperture. That's about six feet across. Not too bad, but small by today's standards. The Discovery Channel telescope is a 4.3-meter primary mirror, about 14 feet across, state-of-the-art instrumentation.

Why is it called what it is? Mr. John Hendricks is the founder and CEO of Discovery Communications, contributed - through his own foundation and Discovery - $60 million towards the capital cost of the telescope, jumpstarted the project back in 2003. In return for naming rights and what Discovery wants to do is not tell us what to look at, but use what we look at to use in their broadcasts.

So we and our partners will use this fabulous this new facility to observe things we just can't do right now. You know, we have public tours every day at Lowell and often, people will ask: Now, how far can you see with your telescope? And really, it's more how faint can you see, like this Kuiper belt objects. Celestially speaking, they're right on our doorstep, but they're small, and many of them are not very reflective, so they're exquisitely faint and...

FLATOW: Will you be able to see that with the...

HALL: Right, right. We can do imaging and, even more difficult, spectroscopic studies, where you spread the light out, of very faint objects. And you go out there and stand out there - I think if Percival Lowell is standing there - you remember the Clark Telescope Dome last night?

FLATOW: Yeah. Yeah.

HALL: And all around the perimeter are these tires, the 1954 Ford pick-up tires that rotate the dome. You go out to the Discovery Channel Telescope. In the dome, at 90-degree intervals, are these huge motors, and underneath the motors are these really high-tech tires.


HALL: No, they're very high-tech, and they butt up against this immense steel ring and turn the dome. In aspect, they look very similar to the old things. I think if Lowell were standing out there, he'd be pretty happy.

FLATOW: Well, thank you. Thank you very much for coming by and telling us about that.

HALL: My pleasure.

FLATOW: Jeffrey Hall is an astronomer and director of the Lowell Observatory here in Flagstaff. I'd like to thank Northern Arizona University, W.L. Gore & Associates, and the city of Flagstaff, Flagstaff Cultural Partners for making our visit possible. I want to thank, also, John Stark and all the folks at KNAU for making us feel at home here today.

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