Planetary Radio: Space Exploration, Astronomy and Science - McDonald Observatory and the Quest for Dark Energy

Episode Date: April 19, 2017

The University of Texas at Austin’s observatory is high in the hills of west Texas. In this special episode, Mat Kaplan joins the tens of thousands who visit it each year. The occasion was the dedication of the vastly upgraded Hobby-Eberly Telescope, third largest on Earth.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Off to West Texas and a giant telescope, this week on Planetary Radio. Welcome, I'm Matt Kaplan of the Planetary Society with more of the human adventure across our solar system and beyond. A special show this week as we visit famed McDonald Observatory. If you're like me, you mainly know them through the terrific Stardate radio feature, but wait till you hear what they have begun to do with one of the world's largest telescopes. Bill Nye has the week off as he prepares for the April 22nd March for Science

to say nothing of the April 21st premiere on Netflix of Bill Nye Saves the World. We hope to have an extended conversation with the science guy on next week's Planetary Radio. Head east on Interstate 10 out of El Paso. Go south when you reach Texas Highway 118. You'll rise out of the West Texas scrub into the green rolling hills that surround one of the world's foremost optical astronomy sites. If you're lucky, you'll arrive on one of the evenings when the McDonald Observatory

adds sharing science to merely doing it. Telescope domes seem to be everywhere. Under some of those domes, starry-eyed visitors are being introduced to the wonders of the night sky. You're going to hold on to this ladder, and you're going to be looking right into that eyepiece. You are looking at those four bright stars in the center. Those form the trapezium, and that cloud that you see around it, that's the cloud of gases and dust still forming into new stars. It's the closest star-forming region to us,

and some of the youngest stars that we know of are in that cloud, just under a million years old. For comparison, our sun is about 4.5 billion years old and is expected to live 10 billion years. Yeah, that light took 1,350 years to get here to meet you. You probably drove a long way too, though. Very cool. Yeah.

Now, wander over to the outdoor amphitheater, where a green laser beam is tracing the constellations above you. There's Jupiter, over there Mars, and there, a nearly full moon. All of them, wheeling around that star we in the Northern Hemisphere know as Polaris, the North Star. that star we in the Northern Hemisphere know as Polaris, the North Star. If this star, Polaris, tonight is like shifting over to there, could you please come find me? I need to know about that. That would be problematic. There would be greater things going on that we need to resolve. The presentation ends and you introduce yourself to the first of several friendly and passionate astronomers

you'll meet in this special place. Later, you'll see one of our planet's most powerful telescopes and talk about its new journey across the cosmos and back through billions of years. For now, it's enough to talk about the sky we can all see when it's clear enough and dark enough. I am Mark Wetzel. I'm the Senior Outreach Program Coordinator for K-12 Education and Teacher Training

here at McDonald Observatory. And obviously well beyond 12, because a lot of people may be feeling like 12-year-olds and younger tonight because I think you've kindled their love for the sky. I sure hope so. I have it. And the reason I've been here 28 years is because I can't get rid of it. It is the most infectious thing. I keep reinfecting myself along with, I hope, everybody. You do a fantastic job. I mean, I've never heard anybody better talk about the sky indoors or outdoors. But who needs a planetarium when you've got a sky like this? I know it's so fantastic. And, you know, we do have clouds once in a while.

I hate to say it, but when we do, our jobs get harder. But they're just as exciting and thrilling and engaging because we can then do some things that we wouldn't otherwise have an opportunity to. we can then do some things that we wouldn't otherwise have an opportunity to. And unfortunately, I didn't have my recorder running when everybody suddenly went, because you get surprises here that you don't get in a planetarium. I know, naturally occurring things that no one has seen before, like a meteor. Yes, I was pointing at a part of the sky with my pointer showing constellations, and a big meteor streaked across the sky right just then when everyone was looking and I sort of feel personally responsible when those things happen of course. I'm here mostly

because of the science that goes on here because of what we'll be doing at the the HET the big telescope tomorrow. Clearly there's much more than that happening here I mean it's what why you have a job here and it's why there are hundreds of people here tonight. Right, 75 years and more. We have had a mission here at the observatory to be a world-class research facility, to lead in research and astronomy, and to make it accessible to the public. Everyone can come here and get a bite of the thrill of discovery and the process of science. Where are these folks from? Are they locals? Do you get that they come from all over the country? You'd be amazed. We have people tonight, probably I think 75%, 80% of the people here are from Texas. We have a lot of people that are from other states here in the United States, but we have folks identified themselves tonight as being from Scotland, Australia, Germany, and Mesopotamia, Ohio. Yes, I was there. Between the two rivers,

but not the Tigris and the Euphrates. The gentleman was very clear to point out that he was from Mesopotamia. How often does this happen? We do this three times a week. Wow. And you get crowds like this? We do. We do. The crowds have grown. When I first started working here, it was really interesting. We had, interestingly, more people that showed up during the day for a guided tour. And we might have had a few tens of people that would show up at a star party. Goodness, if we had 100 people, we would have panicked. Now, a common star party has 300 people at it. And when we have spring break periods like vacations, we have close to 1,000 people at a Star Party. Everybody's got that story, all of us who love the sky like you,

about the first time we look through a telescope. You must hear that scores of times every night. I do. I have people who have looked at the sky, and they've loved what they've seen as children, and they come here and get a great experience that reinforces that. But then just as frequently, I have people that have come here who have been raised in cities who have never seen this before, and they're really amazed, and it makes me feel like I'm taking someone on a nature hike for the first time and showing them

an oak tree for the first time, or a squirrel, or a river, because it's really all part of nature. Tell me a little bit about the slightly more formal stuff that you must do as the K-12 coordinator. Right. So I follow a science teaching pedagogy that is really firmly in place right now because we've identified the real way that children can appreciate and love learning science. And we do that with kindergartners all the way up to 12th graders when they visit with their schools. And then I also turn around and I get those teachers in a classroom and model how to teach astronomy and make it thrilling and exciting for them. Because teachers, while they are trained to know how students learn, many teachers don't have sufficient training in astronomy. So we teach them astronomy. We put them in the role of being a

student during the summer. Do you know off the top of your head how people can learn more about how to take part either here in person at the McDonnell Observatory or find opportunities for their classroom? Essentially as many people would say these days in our society, our digital society, go online and check our website mcdonaldobservatory.org. But, of course, we also have a great publication called Stardate. Stardate is a wonderful extension of McDonald Observatory's research out to the general public where individuals can read about current research taking place and even look at a star chart. And that's a great way to go about doing it.

Can I come back some night on a new moon? Yes, yes, yes, yes, yes. So you're here on nearly a full moon night and it's bright, the sky's bright and that's just amazing in itself how bright the moon is when you're in the middle of nowhere. But yeah, on a new moon night,

totally different experience. Pitch black sky, it just falls on you. The stars just become party everywhere you are. It's beautiful here. I'm going to let you get back to showing people Jupiter and the other wonders of the sky. Thank you so much. It was great talking to you. You too. And have a great time, everybody. Thank you a lot for being here tonight. Thank you. Mark Wetzel of the University of Texas MacDonald Observatory. After spending the night in nearby Fort Davis, you're up early to visit the observatory's crown jewel.

It's the rededication of this gigantic instrument that has brought you here. The Hobby-Eberly Telescope, or HET, is under a silver dome high above the observatory's visitor center and most of its other telescopes. It only reopened for business a few months ago after an upgrade that has prepared it to help uncover perhaps the greatest mystery in astronomy and physics. Only a fisheye lens could capture the scope of this behemoth. Its giant mirror turns but does not pivot up or down. That's one reason this scope, the third largest optical instrument on Earth, costs so much less than other telescopes in its

class. Instead, well, I'll let Herman Creel introduce you to it. Herman is the project manager for the HETDEX upgrade. That's Hobby-Eberly Telescope Dark Energy Experiment. We'll hear much more about that dark energy research later, but Herman is showing us his very large baby. That's our primary mirror. It has 91 individual hexagonal segments. You can see it sits at this angle of 35 degrees off the vertical because that's what we explained this morning this telescope can only rotate in azimuth on top of this concrete ring in elevation it's fixed at this 35 degrees from from vertical so that's why the mirror sits at this angle and then up there is that black machine that you've seen in some of the pictures that I've shown that's what we call the tracker. Anyone feel like driving the telescope? Okay so

you're gonna hold this and what we're gonna do is first is activate the system. Next thing is you're gonna press this button and then there's gonna be air flowing in there so just be aware of that. So now you'll see these feet lifting up you'll see that the telescope raises up, there he goes. Oh. Okay. So how many tons is she moving right now?

150 tons. Got a feeling of power? Oh yeah. I'm also scared. Break it, you buy it. So here you can see all the pipes coming in that bring the liquid nitrogen in so maybe you can sit down the telescope here and just press that button so now the telescope will settle you can see the feet are now settling down on the concrete again

and then after a while we'll just release the air and the telescope will settle in position we gaan die lucht verlaat en die teleskoop sal in posies sê. Ek het die foto van die aarde van die plaat waar al die ontspreekers gaan. Mense vraag ons vaak as ek die veiligheidsnet is. So, al wat ons doen op die teleskoop, is duidelijk dat ons op hoogte werk, so ons draai veilige harnes. Maar as ons omhoog klim in dit muur, in dit wat ons het gehoor, the truss, the mirror truss,

the cables get snagged on the harnesses and it just causes more harm than good. So this is the only place where we climb around without safety harnesses. So the safety net is there just to break the fall a little bit. Fortunately we haven't had any incidences. People climb around inside there as if it was what kids here would call a jungle gym. Correct, yeah. Yep, that's exactly it. We're having a lot of fun climbing around and things, you know.

Now we've gone back to the beautiful visitor center to meet the man in charge. Director Taft Armendroff spent eight years at Keck Observatory in Hawaii. Now he holds the Frank and Susan Bash Endowed Chair at UT Austin. Director Taft Armendroff spent eight years at Keck Observatory in Hawaii. Now he holds the Frank and Susan Bash Endowed Chair at UT Austin. He is the first of three astronomers we will talk to about this magnificent telescope and the observatory that operates it. I was embarrassed to admit that while, of course, I'd heard of the McDonald Observatory, if only because of Stardate, there has been terrific science going on here for many decades. Thank you so much. You know, we're a little out of the McDonald Observatory, if only because of Stardate. There has been terrific science going on here for many decades. Thank you so much. You know, we're a little out of the way,

hiding from the light pollution here in West Texas. So not many people just happen upon the McDonald Observatory as people do on, say, the observatories surrounding Tucson or in Southern California, which are so well known. And particularly with this telescope that came online, saw first light right in 1996, I think, it's a very big telescope. Yes, 10-meter diameter mirror. And we've recently expanded the field as part of this upgrade to the largest field of this generation of 10-meter telescopes. So the field is 70 percent the size of the full moon. So we have that field filled with optical fibers to do spectroscopic surveys now with this upgrade. So a really good telescope to do surveys, to look at a lot of stuff.

Absolutely. So much in astronomy we learn by big statistics and by correlations. So surveys mean a lot to us. I think about the impact of the Sloan Digital Sky Survey over the past decade. Some of the highest cited papers are from big surveys now in astronomy. And we want the Hobby-Eberly telescope to be right there doing really impactful science and surveys. So you've put another $40 million into this telescope. We heard earlier that in some ways, it's almost a new telescope, even though it's the same mirror. That's, in one sense at least, kind of a gamble. You talked about that.

It is a gamble. It's a bigger bet probably than most observatories would make. If I go back to my time at CAC or I've been associated with the Gemini Observatory as well, I don't think any of the other observatories that I've had the honor to be associated with would have done this big a gamble to, in effect, replace everything except for the primary mirror, the dome, and the structure, replace all the instrumentation, change out the tracker. The tracker is what allows the Hobby-Eberly Telescope to track stars across the sky as the Earth rotates, put in a whole new optical

corrector to bring into focus a much wider field of view. It is a really serious investment. If we were playing poker, we would have taken all of our chips and put them on this upgrade and the impact it's going to have on areas like cosmology, dark energy, exoplanets, and galaxy evolution. Was this facility, McDonald, in a better position to do something like this because it's a university-operated facility than, let's say, a federally run one? I think it would be hard to do this on a federal facility because you're enabling the cosmologists and those who are passionate about dark energy, but there's winners and losers in giving out the telescope time and in the investment you make in the telescope. So we're making a determination that this is worthwhile to sacrifice the work in some other areas, although we will be very active with exoplanets, stellar

abundances, galactic archaeology during the bright of the moon with the Hobby-Eberly Telescope. But we're making a big bet on our dark energy, and we've had a consensus among our scientific community, which is a smaller scientific community than the entire national community, of course. We've had a consensus that this is a very good investment and that there should be some really interesting and signature science that comes out of this. I think our audience knows that there certainly has been a trend toward bigger and bigger telescopes. I never realized that there was sort of a Moore's law of telescope mirror size, which you also talked about a little bit. That's right. Going way back to Galileo, if you make a plot of telescope mirror size versus time, there's a doubling over some characteristic period.

I think it was something like 40 or 50 years. The Hobby-Eberly telescope and the CAC fit on a linear and log space plot going way back to Galileo. It's just incredible. space plot going way back to Galileo. It's just incredible. Paralleling that, but much less known to the general public, is this effort to create better and better spectrographs. And it sure sounds like you guys have leapfrogged a lot of, I don't know if I want to call them the competition, because of course they're your colleagues, but you really have the beginnings of one heck of an instrument. Yeah, on our team here at McDonald, Gary Hill and Philip McQueen and others have pioneered this mass producing of spectrographs. So I mentioned earlier that we have something like 35,000 fibers coming off of the telescope.

In the classic sense, we could have made one huge spectrograph where we arrayed these 35,000 fibers into. It would have had huge optics. It would have been absolutely unique and been very expensive. Our team decided that it was more economic to put the 35,000 fibers into of order 150 spectrographs, make their optics smaller, make their detectors smaller, and mass produce them. So you have one design for this spectrograph. And when you buy parts that you

can have made in job shops or optical shops, the price of the second optic and the third optic and the fourth optic just keeps going down because they know how to make it. This is extremely cost effective. And we think we would have introduced a lot of cost and a lot of risk, and maybe we couldn't have done the project if we hadn't done it in this mass-production sort of way with the spectrographs. They're not all there yet, but eventually you'll have how many of these individual spectrographs? 156. There's then four additional spectrographs that have been slightly tweaked to have somewhat

higher spectral resolution and cover the full optical band. We've really gotten our money's worth out of the design. We were treated last night to one of your star parties. It was fantastic. I mean, how big a part of the mission here is the public outreach? Oh, it's a huge part. Going back to the benefactor of the observatory, Mr. McDonald, who said in his will, we should not only discover new knowledge about the universe, but we should share it with the public. We've taken this very seriously. So I encourage your listeners who haven't visited before to stop on by McDonald Observatory if you're going through Texas. We get on the order of 90,000 visitors a year.

We have tours, star parties. And we even take some time off on a couple of the research telescopes a certain number of times a month to allow the public to look through those. We have our Stardate radio program and our Stardate magazine. So we're very enthusiastic about it, and we're thrilled that the public wants to learn about astronomy. And we'll put a link up, of course, to the McDonald Observatory on the show page that people can find from planetary.org slash radio, but I'm sure it's very easy to Google as well. Absolutely.

We look forward to seeing you all, and it's been a pleasure hosting you out here at the observatory to show you behind the scenes and let you kick the tires. For us as well. Thank you, Taft. It has been a wonderful visit. Thank you so much, and best of luck with the program. McDonald Observatory Director Taft Armidroff. When we return, we'll meet two more astronomers who have bet their professional lives on the newly upgraded HET. And one of them will help us imagine that mysterious something that appears to comprise most of our universe. For lack of a better term, we call it dark energy. This is Planetary Radio.

I'm Casey Dreyer, the Planetary Society's Director of Space Policy. In the last five years, our members have helped to achieve pretty much every single advocacy priority we've had. It's been amazing. NASA's planetary science budget is above $1.5 billion again, and it's growing. We have new missions to Mars in 2020 and Europa. We've sent over 400,000 letters to Congress and the White House in order to achieve this. And your generosity has enabled us to grow this program up to three full-time staff

dedicated to space policy. But we have a new Congress, a new president, and soon a new NASA administrator. Decisions are being made right now that are going to impact the future of NASA for a generation, if not more. So we need your support now more than ever to build on the momentum we've created here. So please, join us. Invest in our advocacy program. Go to planetary.org slash advocacy. Thank you. Welcome back to a special edition of Planetary Radio. I'm Matt Kaplan, continuing our exploration of McDonald Observatory and its giant Hobby-Eberly Telescope. By the way, there are great images on our show page at planetary.org slash radio.

Larry Ramsey chairs the Hobby-Eberly Telescope's board of directors, but this astronomer has been much more to the project than that. It has dominated much of his life for more than 30 years. While he also works for the University of Texas, Larry is primarily from Penn State, where the HET project was first envisioned. Penn State and UT are joined by three additional international partners. I hated to see the telescope come down because it was doing great. But this HETDEX and the way we're reconfiguring the telescope is going

to really allow the HET to reach its full capability in furthering science. This is like an accelerator that has had a major upgrade. It's not a new accelerator. It's had a major upgrade. It's like somebody added superconducting magnets. Basically, that's a good analogy. The optics at the top end, our original optics was not optimum because we really didn't know how to build those things back in the early 2000s. Optical fabrication has come. And frankly, these optics that we existed, probably the most complicated optics ever put on a ground based telescope it was tough. The telescope performs much better than the old telescope

ever did. It's pointing is better, it's image quality is better it's tracking is better so the old telescope has been made to hum at a much higher level of performance than before the only problem we have now is we only have one instrument and it's primarily a dark time instrument. The high-riddle zone planet fighter that we were just talking about a little while ago won't be on until September or something like that. The high-resolution spectrograph, probably similar time scale, and those are the bright

time instruments. So there are people itching to use it, but the instruments aren't there. There was a conscious decision to kind of go out on a limb, that there was a bit of a gamble involved in designing, redesigning this telescope to go after one thing in particular. It's definitely a risk. But you know, without risk, there's no reward. And we're going for the reward. And frankly, you know, in many ways, we have no choice but to do that because our telescope is not a telescope that does everything.

It's a survey telescope. You've got to say something about the habitable planet finder and what that's going to mean for identifying, finding these worlds that resemble our own. Well, we're excited about that. It's a very challenging experiment. Again, it's high risk, but again, high reward. We know that there is great science that can do. If we don't find the planets, I think we may find out a lot about these dwarf stars that populate the galaxy. But we will discover planets.

The question is, do we discover a planet that we actually feel has a high probability of life? That's why we have to look at so many hundreds of objects because a lot of these things will be too close to the star. The planet will be just a little too cold. It won't be in that Goldilocks zone. It won't be in that Goldilocks zone. So basically, you have to do a survey. This is what astronomy has come down to for the last two decades,

is doing surveys because we know things exist out there, but we don't know how frequently and we don't know all the details. Penn State Professor of Astronomy Larry Ramsey. I've saved the most fascinating conversation for last. Carl Gebhardt has an unfair advantage in that regard. The University of Texas at Austin astronomy professor has been project scientist for the HET dark energy experiment since 2006. As with everyone else involved with the telescope, it has been a long and challenging journey, but now the science and the fun have begun. I get to talk to lots of terrific people.

I consider them heroes. But some of them are so good at communicating the passion that I think all of them feel. You are one of those who sure appears to love this and loves to share it. I do. I love that. I've been teaching a course at the University of Texas called Popular Astronomy. It's kind of a play on having how the press makes the news and we astronomers tend to follow it around. I love teaching these to

non-science majors. And one of my favorite things is to challenge myself to explain some of the hardest topics that are out there. I love doing that. You've got to talk about this metaphor of our fingerprints and how that applies to the kind of study that you're doing. What we're doing in HETDECS is we're trying to measure the expansion rate of the universe. And how we do that, all we have that we can use are galaxies. So we look at the distribution of galaxies. And what's special about our universe is that when the galaxies were distributed early on in the universe, it wasn't a random, completely smooth pattern. There was a fingerprint that these galaxies were distributed in.

Much like a human fingerprint, if you wanted to measure how fast you've expanded over time, if you want to know what is your expansion rate as a human as an individual what is your expansion rate one easy thing to do is to take your fingerprint and you know for the mothers and fathers out there now you can start to sign your kids right now take a fingerprint of the of your child and do it i don't know every week every month for their whole. And then you measure the space in millimeters between the ridges of your fingerprint, and you just track that space as a function of time. You make a plot of it, and that's it. That's your expansion rate.

We are doing a very analogous thing with galaxies, as we're measuring the average separation of the galaxies in the universe, and you do that as a function of time, and that's it. That's the expansion rate of the universe. I really love that metaphor. Are you now kind of a kid in a candy store with this new, essentially new telescope? We have this new telescope on, Javi. I believe that I just, I get too excited. I look at the data. I'm not getting a lot of sleep over the last six months. We're getting data every night.

And every night, I find something new. How often, so do you get to say, every night, I am finding galaxies, hundreds of galaxies that are 10 billion light years away that no one has seen before? How often do you get to do that? That's, like, so exciting. And many more to come. Many more to come. Right now, we are about one-fifth the capacity. So we're going to increase our instrument in size by a factor of five. Right now, we are the largest instrument on the world in terms of the ability to cover the sky with spectra. And so we're going to increase

that already by a factor of five once we start. And so hopefully by the end of this year, we'll be at that point. And then we'll go full swing at the survey. I won't be able to look at this stuff individually anymore. Right now, it's kind of nice having just a handful. I can look at each one. I know the instruments by name. I know, oh, yeah, that one's got that problem.

That one has this issue. I'm looking forward to the day where I don't have to do that. And I'm just reducing and analyzing all the data that is coming off. What is this telescope going to do for our understanding of dark energy and ever so slowly closing in on what it really is? So we took a new approach when we designed this experiment close to 15 years now, we are looking at an epoch, at a time in the universe where no one else has looked before. So we're looking at the universe as it was expanding 10, 11 billion years ago. Most of the other experiments are looking at the universe as it expanded about 4 billion years ago. And so what we're after is the differential there, because

one of the best ideas out there is this idea called the cosmological constant. And focus on the constant. The constant means that as a function of time, that value, that contribution of the energy density should not change for whatever we're calling a dark energy. And so we are going to a different epoch on the universe and trying to see if the constant is really a constant. There's another tactic there. We could have gone to the nearby universe, like the other programs, and just really nailed what the expansion rate is. But we chose to go for the exploration,

to go for the discovery, to go for a new epoch on the universe. And that's what I love, right? I mean, we haven't looked at this before. Just to make it clear, we have looked at the expansion rate of the universe. We collectively, as the whole community, has looked at it once as it expanded 4 billion years ago. And we found a major problem. We found that it was expanding much faster than we thought. That's one time. One data point is not great. One data point is not enough.

And so that's the point. Exactly right. So we're going for more. Why were there people who said, oh, you're crazy to be looking back 10 billion years? There was a lot of competition early on trying to build a dark energy experiment. I could go through a good 10, 12 experiments that are out there. There's really only a handful left standing, probably three or four. And so I think people were overly critical of the

other ones because everyone was vying for the same amount of funding. Now, also, to be fair, yeah, we thought that dark energy was a late time phenomenon. That means we only see it once the universe expanded to a certain size. And so we're going so far back in time that the expectation was dark energy may not have the influence that it has today. And so we wouldn't see as a big effect. But our whole idea was, look, the theorists were wrong the first time. And so now they make a prediction for what's going on in the past. We need to go and look.

What happens if this cosmological constant turns out to not be very constant? Well, if that's the case, that's fantastic. So if I had to choose where HETTEX would have the biggest impact, I think just making that measurement that we will have at 10 billion years ago is going to be fantastically important. But if it's changing, if the value of this constant, if it's actually not a constant, that's monumental. That means something fundamentally is different about a universe than what we thought. It could be, for example, that gravity is not doing what we think it's supposed to do. It could be that there's a new type of force out there that we have yet to discover. A fifth force. A fifth force called quintessence. We even have a name for it, the fifth essence. So the fifth force. It's a good movie too.

That's right. A terrific movie. One of the other things you talked about in your little presentation to us was, what if we discover as we look at different, in different directions in the universe, we find different figures. I'm so excited about that one, too, because this was something that I pushed early on that it was hard. So most of the dark energy experiments are taking all the data over the whole sky, and so they can't see a differential effect. A fundamental tenet of cosmology of our universe of the Big Bang is that it's the same everywhere. Wherever you are, the universe should look the same, that it should be expanding the same.

And again, I am not going to sit back and just take what the theorists and the cosmologists have been used over the years as this should be assumed. So what we have designed, HETAX, is we're going to look at two distinct areas on the sky, and we'll measure the expansion rate in both of those areas. If we find a different number there, that, again, would be monumental. Again, the expectation is it'll be the same, and it probably will be the same. But I want to cover our bets in that case. If that were to happen, would that be possible evidence that we live in just one of many universes? So the idea that you could see evidence of the multiverse is hard for me to argue for.

So the answer to your question is yes. Certainly, there'll be some people who say, oh, evidence for the multiverse. But that is so hard to show observationally. It's almost in a regime where it turns to philosophy. That is, if you can't make a definite prediction to rule out other universes or to see evidence of, then is it really science? Yeah, yeah. Oh, well, a guy can dream. You made a colleague stand up during your presentation and show off his T-shirt. The front was a formula.

The back said something very interesting. Okay, so what I've been saying for a long time, dark energy is this idea. It's a phrase we use to explain the ignorance of how the universe is expanding. And on the back of the shirt, as I always said, it may not be dark. It may not be energy. It's just a phrase, just a simple phrase. We could have called it the ignorance parameter. If I had seen this, I could have said, okay, so there's our ignorance parameter.

Maybe it's energy. I think that's unlikely. Whether it's dark or not. For example, if the extra influence, the extra expansion of the universe is due to a modification of gravity, then this thing doesn't even exist, right? It's a modification of gravity. We got the laws of gravity wrong. And so this term that we invented, which we called a dark energy, we can now get rid of and we can put it into gravity. We've tried to work that and it hasn't held up that it's a modification of gravity. But this is why this phrase, a dark energy, might be seen as misleading

in some case. This is incredibly exciting stuff, right? I mean, it's almost like in the 19th century when everybody thought they understood the universe and physics, but they didn't. Right. I compare it to the atom. In the late 1800s, you know, we had this idea of the atom. It really was until we understood the constituent particles of what's inside the atom and being able to break it apart that we really understood the fundamentals of the physics in that area. We don't understand the base components of what's in the universe. It's remarkable at this point. We don't understand dark energy and dark matter.

They combined, as far as we can tell, make up 95, 96% of the energy density in the universe, and we don't understand that. So we don't understand the basic, the essence of what's in the universe right now. Good times. It's great times for employment for astronomy. That's right. You're finding more than galaxies. Some other exciting stuff out there. We have 35,000 optical fibers that we're putting on the telescope. About 3% of those are the galaxies that we want. You can do the math. That's 97% of the remaining spectra that we're getting is other stuff.

And we need that many fibers because we don't know where these galaxies are, and they're relatively rare. So we need that many. But this other stuff out there is rich. And this is, you know, I get excited by that as well. It's not necessarily cosmology, but it has to do with weird galaxy. is rich. And this is, you know, I get excited by that as well. That is, that is, that is, it's not necessarily cosmology, but it has to do with weird galaxy, weird stars, naked black holes, these rogue black holes that got ejected from a galaxy that only have an accretion disk floating around them. We will find those things if they exist in the right numbers.

That stuff is just a goldmine. This is the essence of science. This is the discovery. That stuff is just a goldmine. This is the essence of science. This is the discovery. This is why I got into the field is that you make these discoveries. And so finding those interesting objects, I just can't wait for that. Maybe I have them already. I just don't know.

Can I check back with you in, oh, three and a half, four years? Sure. And a year from now, we'll have something. I'm sure of it. Thank you, Carl. Thank you. Carl Gebhardt, project scientist for the Hobby-Eberly Telescope Dark Energy Experiment. My gratitude goes to all the great folks at McDonald Observatory and the University of Texas at Austin for enabling me to tell this story, including my host, John Stoke. The observatory is well worth a visit.

Learn more at mcdonaldobservatory.org. Bruce Betts is on the Skype line. He's the Director of Science and Technology for the Planetary Society. We got a message from Michael Godwin. He says, I wear my Planetary Society pin every day. I try to show it off at work, but no one ever questions me about it. Is there any way I could donate more money for a larger pin? Didn't you experiment with this? I did. Engineers and I looked at a design that was about, oh, I don't know, 10 centimeters, 6 inches in diameter. Probably shouldn't have made it out of depleted uranium.

It was a little heavy, a little big. Kept ripping people's shirts. At one point, Bill Nye actually just fell over. Well, he's pretty tall and thin. Yeah. So we went back to this. There's probably a happy medium somewhere, but it was awesome in its brief life. Michael, the research will continue.

We'll let you know. What's up? Planets. Jupiter now just looking lovely in the early and late evening sky, hanging out in the east and the south. And we got Mars getting kind of low in the west in the early evening. Saturn coming up around 1 a.m. in the east. And Venus now getting higher and higher in the pre-dawn sky. There are also three comets that can be seen as fuzzy blobs with good binoculars, or certainly with a small telescope. If you're interested, I'd look up finder charts on the web. They're not visible with just the naked eye. We move on to this week in space history. 1990 Hubble Space Telescope was deployed this week. It's been working a really, really long time.

We're still waiting for some decent results from it, though. Yeah, really. Any day now, real science. Real science. Maybe some pretty pictures or something. All right. So we move on to random space fact. That just attracted my dog over.

I'm not surprised. Hi, Max. You know, and had a wonderful show about the TRAPPIST-1 star system where seven planets similar in Earth's size were discovered recently. All of them much closer to its parent star than Mercury is to the sun, all within 6% of the Earth's sun distance. But because the star, as was discussed, is a red dwarf, so much cooler than the sun, still puts three of the newly discovered planets within the habitable zone. It's just, it's a weird system.

As we continue to learn about the enormous diversity of planets and planetary systems across our galaxy. We do. I happen to be lecturing in my class today about exoplanets. You probably couldn't tell. But you're set to go. I'm glad to have given you a little practice run. All right, we move on to the trivia contest.

Glad to have given you a little practice run. All right, we move on to the trivia contest. I asked you, who first noted what turned out to be Neptune, though he's not credited with the discovery because he didn't note its movement and likely thought it to be a star? This is so interesting, and people love this. That's what I thought. Yeah. They also love the chance to possibly win the last Planetary Society rubber asteroid for a while. That really

turned people out. We've always said we're trying to keep asteroids off of Earth. That's true. It's that is part of our mission. Even the rubber ones, apparently, although I think there is talk of buying some more. I hope that happens because they're just great. And I'm happy to say it appears to be Jenny King of Bailey, Colorado, that is going to get that last rubber asteroid. This is how she put it. Ooh, this is an interesting one. It seems that Galileo may have noted Neptune in his notes in 1612 and 1613. She says his telescope wasn't quite powerful enough to resolve it as a planet, so he seems not to have been terribly intrigued by it. Was she correct?

That is correct. Amazingly far ahead of its actual formal discovery. Truly amazing. I mean, Galileo, what a guy. What an idiot. You know, he discovers a planet, doesn't even notice. Well, there's another reason. I hope that guy does something more effective someday.

Yeah, everyone has high hopes, just like for the Hubble. I know, I'm just attacking all the lame-os of astronomy. There was another good excuse for Galileo not to realize he had found a planet. We heard this from a whole bunch of listeners, including Perry Metzger and Craig Balog and Melissa Wiedzinski. It was his just bad luck. Neptune had just gone into retrograde motion, so it really didn't appear to be moving much in the sky when he looked at it. So, So it really didn't appear to be moving much in the sky when he looked at it. So sorry, Galileo, you just missed out there, just barely anyway.

Jenny was correct. She says she proposes that the final asteroid prize be neatly autographed by everyone named Bruce that you can locate in the next hour. And go. Considering we're very far apart right now, that probably won't work out, but I think we can make it happen from someone named Bruce, at least. Jenny, we will get the Director of Science and Technologies, John Hancock, actually his Bruce Betts on that last asteroid for you. I'm going to go ahead and pretend that she wanted my signature. Norman Kassoon actually sent a little bit of the notes actually made by Galileo in his notebook that shows this diagram with Neptune offset from Jupiter a little bit. Dustin Segrist says, wait a minute, more recent studies of Galileo's notes reveal that he

may have hypothesized that it was a planet. Here's another reason why he may not have claimed it that we got from Ian Kennedy in Dundee, the UK. He says maybe he just didn't want to appear greedy after already finding as much as he had. Let's leave it for someone else. By the way, it wasn't until the mid-1800s that it was formally discovered and he was looking at it uh well over 200 years before that back to exoplanets as of now ish approximately approximately because everyone disagrees a little on the numbers, so we'll be flexible on this. How many confirmed, confirmed exoplanets, planets around other stars, have been discovered?

Go to planetary.org slash radio contest. There are a lot of good sites where you can find this, or, I don't know, listen to my class. Where can they catch that? Planetary.org slash Betts class. And how close do they have to come with this? I mean, not dead on, right? I'd say within a hundred. Of course, watch. Kepler will release a thousand confirmed planets tomorrow. If that happens, we will deal with it and be flexible. But otherwise, within roughly a hundred. Because the confirmation, there's a little,

you know, what's a candidate exoplanet and what's a confirmed exoplanet. there's a little, you know, what's a candidate exoplanet and what's a confirmed exoplanet. There's some slop, but it's, I think the agreement is within 100 or so. All right, we'll go easy on you. You have until April 26th, that's Wednesday the 26th

at 8 a.m. Pacific time to win yourself, well, the adulation of thousands, of millions around the world. Also, a Planetary Radio t-shirt and a 200-point itelescope.net account. That network of telescopes operated on a non-profit basis out of Australia, but they are everywhere and you can image anything you want in the cosmos, as long as it's not too bright, I'm guessing. All right, everybody, go out there, look up the night sky,

and think about whether Darth Vader had to shave. Thank you, and good night. You have to be so careful with the lightsaber. You really do. That's Bruce Betts, the Director of Science and Technology for the Planetary Society, who joins us every week happily here for What's Up. Hey, how about we add one more great item to this week's prize package? You remember Dante Loretta, principal investigator for the OSIRIS-REx asteroid mission?

Dante has followed up his very successful creation of the Extranaut board game with something new. Constellations is the game of stargazing and the night sky. Dante is wrapping up the Constellations Kickstarter campaign and wants the winner of the new space trivia contest to own it. You know where to go. I'll be at the Cedarhurst Performing Arts Center in Mount Vernon, Illinois on Saturday, April 22nd. It's the WSIU Cedarhurst Star Party,

sort of a kickoff for the big eclipse celebration coming to Southern Illinois University in August. And speaking of the Great American Eclipse, have you heard about the Eclipse Mega Movie? 1,000 amateur astronomers and photographers from coast to coast along the path of totality are desperately needed for this outstanding example of citizen science. You can learn how to join the project at eclipse mega dot movie. We'll meet a couple of the project leaders on an upcoming episode of Planetary Radio, which is produced by the Planetary Society in Pasadena, California, and is made possible by its farsighted members. Daniel Gunn is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser.

I'm Matt Kaplan. Clear skies.