Jan 11, 2022 —
Grab your binoculars and step outside on these clear winter nights. You’ll see Mercury rise up towards Saturn, with Jupiter nearby, before Saturn sets in late January and Jupiter sets in late February. Image courtesy of Aileen O’Donoghue.
This month during our astronomy chat with Aileen O’Donoghue, physics professor at St. Lawrence University, it’s all about the James Webb Space Telescope, which has finished unfolding it’s large 18 hexagonal mirrors after launching in late December.
AILEEN O’DONOGHUE: It’s been huge that they got the deployment complete in all its complexity. I mean, these five sheets of gossamer thin, almost Mylar that create the sunshield. They’re the size of a tennis court.
MONICA SANDRECZKI: Wow.
O’DONOGHUE: And they deployed these things, and that all of these steps went well! I was watching on NASA TV every morning as they were going through this. It’s just amazing. It is going to teach us so much about different things in the universe. We’ve been waiting for it since the 80s and it’s been supposed to launch for like 10 years. The astronomy community was holding its breath (when it launched) on Christmas Eve.
SANDRECZKI: Yes, I was reading that some NASA scientists felt like this was like one of the biggest accomplishments was even just getting those mirrors opened up.
O’DONOGHUE: Yes to unfold all that stuff and that it worked! So the next step – and that’s going to take a few months – is getting those mirrors aligned. There are 18 independent hexagonal mirrors, they can move on, like one 10,000th of a human hair. They can move them in three dimensions back and forth, up and down, side to side, and then they tilt as well, and then move them around to create a really sharp image. It’s just gonna be magnificent. And, since it’s a team, we hopefully won’t run into a problem like Hubble.
SANDRECZKI: What’s its path going to be? Because it’s headed towards a final, sort of, resting place. Is that right?
O’DONOGHUE: Right! It’s going to the second Lagrange point, so what this is, Earth and the Sun, Earth orbiting the sun; they both have a gravitational pull and there are some points where those gravitational forces and the rotational forces give you a balance point. There’s one directly between Earth and Sun. That makes sense. Oh, yeah, there’s place where you fold equally, but there’s one on the far side of Earth as well. So, that’s where James Webb is going.
The James Webb Telescope as it heads into deep space. Credit: Arianespace, ESA, NASA, CSA, CNES
O’DONOGHUE: So it’s going to be beyond Earth by about 100 million miles. And… it’s not that far, I’m losing my mind. I’m just suddenly doubting my numbers that I looked up yesterday. Oh, it is!
It is 100 million miles, so it’s well beyond the orbit of the moon. It’ll sit out there; it will orbit the sun at the same rate as the Earth; it’ll just sit there still in our sky, so if you can figure out the point, directly away from the Sun at midnight, you can look out, not straight overhead, but out at an angle, you’ll be able to see the point where the James Webb Telescope is sitting in our city, midnight sky; it’s going to orbit this kind of equilibrium point.
The reason that we want it that far, is because it observes in the infrared; it observes in what we detect as heat…
SANDRECZKI: Which is different than the Hubble…
O’DONOGHUE: Right. It does see some visible wavelengths; it sees into about a gold color, a little redder than the gold of the mirrors, is as far into the visible it sees, but then it sees to much longer wavelengths, like the night vision glasses that soldiers and firemen wear.
The reason that we need it to do this is because we want to look at the early universe.
The universe is expanding, so that means that an object that emits a visible wavelength emitted a visible wavelength as it has crossed the universe, has gotten stretched so that it’s now in the infrared.
With James Webb, the most exciting stuff – well, for me – is that we can look at objects very, very early in the universe, objects that were being formed 100 million years after the beginning of the universe.
These galaxies that we see as red smudges on the Hubble Space Telescope images, well, James Webb is about three times the size and diameter. So nine times the collecting area of the Hubble Space Telescope. It’s gonna be able to see finer detail and see fainter objects.
TODD MOE: Are you saying, Aileen, that we’re in for a treat in terms of amazing photographs?
O’DONOGHUE: Oh, absolutely, absolutely. It’s going to be probably not as big a leap as Hubble was because we lost the fuzziness of the atmosphere, but almost as big a leap in terms of what we’re going to be able to see. Plus, that it can see through dust that blocks visible light, dust does emit, but it emits at different wavelengths, and the wavelengths coming through it, we can see. So it’s going to also look at the disks around forming stars to see if we can see forming planets. It’s going to look into these dark clouds of gas and dust, like the Orion Nebula and see where baby stars are forming. And so it’s even going to look at Mars and look for molecules of water, and see where there’s water sitting around because some of the infrared can pass through some of the surface materials.
It’s gonna look at Ganymede and see if there’s a subsurface ocean; look at Europa, these nearby worlds, it’s just, it’s going to show us things that we haven’t been able to see.
SANDRECZKI: Those moons of Saturn and Jupiter are amazing!
O’DONOGHUE: Enceladus. Yeah, that has these geysers going off. This little world that’s 100 billion miles from the sun. And it has geysers. So it’s just very exciting. And the fact that it all deployed, and it all worked is just astounding.
MOE: Let’s hear it for origami.
O’DONOGHUE: And you can watch it. I just Googled James Webb Space Telescope, NASA. And they have a you can get to the NASA webpage. And they have a “Where his Webb?” And it is just amazing and looking at that right now. The Webb is 722,000 miles from Earth.
It’s going to see these things we haven’t been able to see: the disks around forming stars to see if we can see forming planets. It’s going to look into these dark clouds of gas and dust, like the Orion Nebula and see where baby stars are forming.
It’s even going to look at Mars and look for molecules of water!
MOE: Well, we got about a minute and a half here, Aileen. So let’s talk about things you can see without a telescope in the night and morning skies.
O’DONOGHUE: Oh, yeah, and it’s gonna be clear tonight, which is why it’s going to be very cold. So get out your binoculars right after sunset and look to the western sky. You ought to be able to see Jupiter; below Jupiter and a little bit to the right about two fists worth you should be able to pick out Saturn and then Mercury is a half of fist away from Saturn and they’re going to be fairly close. You ought to be able to see those two within the same field of view of binoculars. So I would find Jupiter with your eye and then see if you can find Satur. You might use binoculars just to pick it out because it’s still going to be kind of bright because they set, you know, like by 6:30 or something. But get out there six o’clock, or even 5:30. Go out and see if you can look for these. Those are exciting to see.
