Current Events

Current Events: Image Release: Giant Magnetic Ropes in a Galaxy’s Halo

By Stacy Palen

A new composite image released by the National Radio Astronomy Observatory superimposes radio data on a visual image of a galaxy. Magnetic fields here are shown in blue and green, indicating alternate directions.

Here are some questions that you can ask your students based on this image:

1) What is the Hubble type of this galaxy?

Answer: A spiral.

2) How do you know?

Answer: Because there is a disk, viewed edge on.

3) What is the Hubble type of the large galaxy directly above the primary galaxy in this image?

Answer: Elliptical.

4) How do you know?

Answer: There is no disk.

5) The blue and green false color “hair” represents the magnetic fields of the galaxy. Blue indicates that the magnetic field points roughly away from us, while green points roughly toward us. These magnetic fields are described as “spiraling” and as “ropes.” Make a sketch of the magnetic field lines of the galaxy that fits these descriptions and observations.

Answer: This is a genuine question, not a test of their understanding. I am picturing a spiral for each blue/green pair that is roughly perpendicular to the disk. I wonder what students “get” from these descriptions?

6) Are the magnetic fields above the disk of the galaxy symmetric with those below the disk? What might cause this?

Answer: They are not. It could be because the magnetic field is being generated differently, or it could be because the observations are more resolved above the disk than below. That could happen if the galaxy disk was tilted so that the top of the disk is tilted toward us.


Current Events: Probe Gets Close to the Sun—Finds Rogue Plasma Waves and Flipping Magnetic Fields

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Credit: NASA/SDO

 

By Stacy Palen

Just in time for the close of the semester, we get a present from NASA! According to this article on NPR, the Parker Solar Probe has arrived at the Sun, and it’s sending us back some big surprises.

Here are some questions, inspired by the Parker Solar Probe’s recent discoveries, that you can ask your students:

1) In 2025, the Parker Solar Probe will come within 4 million miles of the Sun, which is 1/10 the orbital distance of Mercury. To date, it has passed within about 15 million miles from the Sun (almost 4/10 the orbital distance of Mercury). Make a sketch of the Sun and the orbit of Mercury, and then draw circles that show the closest distance of the Parker Solar Probe so far, and its distance in 2025.

Answer: A sketch.

2) The Parker Solar Probe has observed unexpected spikes in the flow of solar wind, where its speed suddenly increases by 300,000 miles an hour, which is nearly double its normal, steady speed. These spikes last for varying amounts of time, from a few seconds to hundreds of seconds. Convert this information into a graph of the speed versus time for an outflow over five minutes of observation. Assume that two spikes occur, one of 5 seconds and one of 100 seconds.

Answer: A graph.

3) The Parker Solar Probe may answer a question that’s been around for decades called the “solar corona problem.” From the context of the article, or from some general research on Google, describe this problem in your own words.

Answer: Why is the corona so hot?

4) The article repeatedly mentions that the magnetic field “flips” without thoroughly explaining this process. What exactly does this flipping of the Sun’s magnetic fields mean?

Answer: This means that the north end of the magnetic field switches locations with the south end.

5) Why did astronomers think that their equipment might be malfunctioning?

Answer: Because the changes in the speed and direction of the magnetic field were happening much faster than expected.


Current Events: A Missing Neutron Star May Have Been Found after 30-year Hunt

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Credits: NASA/STScI

By Stacy Palen

Supernova 1987a may be the most well-studied supernova in history. But the “corpse” had not been found! However, this may have changed according to this article from Scientific American.

Here are some questions you can ask based on this article:

1) How long ago was this supernova first observed on Earth?

Answer: 30 years.

 

2) How long ago did the supernova actually occur?

Answer: 163,000 years

 

3) Why do astronomers typically not worry about the discrepancy between the times in question 1 and question 2?

Answer: We can’t know about anything that happens until the light gets here. As far as we are concerned, the moment we observe it IS the moment when it happened.

 

4) What is special about supernova 1987a?

Answer: Supernova 1987a is so unusually close that we can see it in detail, and watch it evolve in real time. It is also the first supernova observed for which we had seen the progenitor star.

 

5) Why had astronomers argued that a neutron star (as opposed to, say, a black hole) should result from this supernova?

Answer: The progenitor star was about 20 solar masses. This is in the range between 8 and 25 solar masses, which is expected to result in a neutron star.

 

6) What is the evidence that has been presented for the detection of a neutron star?

Answer: A bright blob within a dense dust blob.

 

7) What will astronomers do to strengthen their conclusions from this evidence?

Answer: Get more data, of course!


Current Events: Moonrise at Sunrise

Moonrise
Credit: NASA/Christina Koch

By Stacy Palen

The image above was taken from the International Space Station by NASA astronaut Christina Hammock Koch and could form the basis for a nice final exam question.

 

1) In this image, what is the phase of the Moon? How do you know?

The moon here is a Waning Crescent. The image was taken looking East, into the sunrise, so north is to the left in this image. Therefore, the Moon is “leading” the Sun across the sky and illuminated on the eastern half. This means it is in the Waning phases.

 

2) If you had only this image to go by, with no caption, how would you know that it was an image of Earth?

The planet shown has a solid surface and a shallow but significant atmosphere. Earth is the only terrestrial planet that fits these criteria.

Other potential answers:

  • It could not be Venus or Mercury because neither planet has a moon.
  • Mars’ atmosphere is too thin to refract blue light in this way.
  • There appears, possibly, to be a hint of colors other than red on the surface.

 

3) Based only upon the image, would you think this planet might be a good place to look for life? What other information could you gather from this viewpoint that would make you more certain of your conclusion?

This planet may be a good place to look for life. The solid surface and the presence of an atmosphere would make me want to investigate further. I would especially want to get a closer look at the surface, or get a spectrum of the atmosphere in order to be totally sure.


Current Events: Naming the Moons of Saturn

By Stacy Palen

I long ago stopped keeping track of the number of moons around Saturn and Jupiter. It often feels like there is a contest going on among astronomers—who can find the most moons around “their” planet! In early October, a report hit the news of 20 new moons discovered around Saturn, many of them in retrograde orbits.

This brings the number of moons around Saturn to 82. The number around Jupiter? Only 79. Neener-neener, Jupiter devotees!

Seriously though, if you are now discussing moons, planets, or planetary formation, this is a timely discovery to talk about with students. Or if you are about to start talking about dark matter, it may be a good time to remind students about Keplerian orbits and Newton’s version of Kepler’s Third Law.

But wait! There’s more!

These moons are not yet named, and Scott Sheppard has decided to have a contest to name them all.

Here are the general rules from the Carnegie Science website:

https://carnegiescience.edu/NameSaturnsMoons

  • Two of the newly discovered prograde moons fit into a group of outer moons with inclinations of about 46 degrees called the Inuit group. All name submissions for this group must be giants from Inuit mythology.
  • Seventeen of the newly discovered moons are retrograde moons in the Norse group. All name submissions for this group must be giants from Norse mythology.
  • One of the newly discovered moons orbits in the prograde direction and has an inclination near 36 degrees, which is similar to those in the Gallic group, although it is much farther away from Saturn than any other prograde moons. It must be named after a giant from Gallic mythology.

Full details are available on the website along with a link to a list of names already used and a little video that describes the contest.

It would be great fun to make a class project or competition (even for college students) to choose a name to submit as a group. It’s the kind of experience that students remember for a long time. Submissions are due via Twitter by December 6.


Current Events: Supermoons and Other Nonsense

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Credit: NASA/Bill Ingalls

By Stacy Palen

In July 2019, I received a few queries about a “black supermoon.” Since I had no idea what that was, I decided to track it down. It comes from a group of click-bait articles like this one, which are apparently taking off from a random article in Travel And Leisure magazine.

In brief, there is a new moon. It’s the second one in a month. Apparently, the Farmer’s Almanac calls this a “black moon.” This new moon occurs at perigee, when the moon is closest and has a (technically) larger angular size.

This has lately become known as a “supermoon.” The astute reader will note that you can’t even see this supermoon because it's a new moon. (Cue GIF of Kermit the Frog flailing his hands wildly in despair.)

In the last few years, “supermoons” of various kinds have suddenly become news.

A quick query of Google’s Ngram Viewer reveals that the word isn’t even in their database up through 2008, which is somewhat reassuring; it certainly feels like the term suddenly started popping up just a couple of years ago! But this was the first I had heard of a “black moon.”

Why does this matter? More astronomy in the news is better, right? Well, sort of.

Suppose everyone gets all excited about going out to observe the “black supermoon” and it’s nowhere near as interesting as they expect. Thereafter, they are less likely to follow up when something truly exciting happens, like the total solar eclipse that is coming to the US in 2024. (Have you made your plans yet? I have.)

Competing for the attention of the public, at this point, is a remarkably difficult prospect. I see why some outlets would seize on the popularity of astronomy to try to get a few seconds of that all-important attention. But in the long run, this is a failing strategy if the “news” fails to deliver what it has promised.

This particular article provides a good opportunity to help students see when they are being “click-baited” since there is literally nothing unusual happening.

A student who really understands the lunar orbit and phases of the moon will react to this article much like Ralphie in A Christmas Story, when he receives his Little Orphan Annie decoder ring and realizes the whole thing is a marketing ploy.

“A crummy commercial?” he exclaims as he throws away his long-awaited prize.

Given the last few years, I expect to see two or three articles like this over the course of the next academic year. Each time a student (current or former) asks about it, I will use it as a “teachable moment” and recommend that they fully engage their baloney detection kit when reading their news feeds!


Posters Celebrating Women in STEM

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By Stacy Palen

This set of nifty (free!) posters came through my inbox over the summer. We printed some of them to hang around the Physics Department, and the College of Science more generally.

In addition to raising awareness of the contribution of women, they raise awareness of the contribution of other marginalized groups as well.

Take a look!


Reading Astronomy News: Japan (Very Carefully) Drops Plastic Explosives Onto An Asteroid

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By Stacy Palen

Summary: Hayabusa2 has been investigating the asteroid Ryugu. This is a sample-return mission, which has implications for Solar System formation and may cast light on the origins of life on Earth.

Article: Japan (Very Carefully) Drops Elastic Explosives Onto an Asteroid

1. Consider what you know about the origin of the Solar System. What are astronomers hoping to learn from Hayabusa2’s mission to Ryugu?

Answer: They are hoping to learn about the composition of matter in the Solar System when it formed. This could confirm or refute our ideas about Solar System formation and the formation of the asteroid belt. The precursor molecules for life are also present on the asteroid, which may give us clues about the origins of life on Earth.

2. The article states that Hayabusa2 “physically touched down” on Ryugu in February 2019, and took a sample of dust kicked up. Go online and read more about it. Describe this event in more detail. Do you consider “physically touched down” to be an accurate characterization of what happened?

Answer: The spacecraft approached the surface and shot a small projectile into the asteroid. A sampler horn collected the kicked up dust and the spacecraft moved on. This is not quite what’s implied by the summary sentence in the news article.

3. Ryugu is less than a mile across, in an orbit between Earth and Mars. Using an average orbital radius between those two planets (1.25 AU), find the orbital period of Ryugu. Convert this orbital period to seconds.

Answer: This is a review of Kepler’s third law. The period is 1.16 years, which equals 3.7 X 107 seconds.

4. The circumference of Ryugu’s orbit is 1.2 X 1012 Divide this distance traveled by the period to find the speed of the asteroid in its orbit. This is the speed that Hyabusu2 must be traveling in order to rendezvous with the asteroid.

Answer: This is a reminder of the definition of the properties of an orbit (what is the circumference, and what is the period). The speed is 32,000 m/s.

5. When was the spacecraft launched, and when is the sample return mission expected to arrive back here on Earth?

Answer: The spacecraft launched in December 2014, and will return a capsule to Earth in December 2020.

 

Image Contributor: Mark Garlick/Science Photo Library, 1 March 2013


Current Event: The Eta Aquariids are Coming!

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By Stacy Palen

Don’t forget to remind your students about the Eta Aquariid Meteor Shower, coming in the beginning of May.  The peak occurs around May 4-5.  This is the last chance for most of us to remind Spring semester students to go out and watch a meteor shower!

This meteor shower occurs when Earth passes through the debris left behind by Halley’s Comet.  Particles lost from the comet continue to drift in the Solar System, gradually changing their position. As Earth moves through space, it passes near the trajectory of the comet and runs into collections of these particles.  The particles burn up, creating meteors as they fall through the atmosphere. This will happen repeatedly at particular times of year, as Earth returns to the same point in its orbit. 

Halley’s comet has a 76-year orbit, so it is a short-period comet. It will not be back in the inner Solar System until 2061.

To watch a meteor shower, go to a clear dark sight where the horizon is not obstructed.  Spend about half an hour in the dark, without your cell phone or other bright light in view.  This will allow your eyes to adapt to the dark. Then just watch for meteors!  They are best seen with the naked eye.

If you are careful and methodical, your observations can contribute to the study of meteors and meteor streams!  To learn more, visit the Astronomical League’s Meteor Observing Program website.


Current Events: We've Landed on Mars! Again!

By Stacy Palen.

As of this writing, InSight has just landed successfully on Mars!  This mission is a little bit different from other recent missions: InSight (short for Interior Exploration using Seismic Investigations) is a lander, not a rover. Because it’s in the news, this is a great opportunity for a brief in-class discussion!

 

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This illustration shows a simulated view of NASA's InSight lander descending on its parachute toward the surface of Mars. Credits: NASA/JPL-Caltech

InSight is designed to investigate the interior of Mars: the crust, mantle, and core.   

A seismometer will measure surface vibrations, which will be used to determine the size of the core, the thickness and structure of the crust, and therefore the thickness of the mantle as well. These same measurements will be used to measure how frequent and how powerful the tectonics are on Mars, as well as the frequency of meteorite impacts.

Heat flow measurements will be taken using a probe that is hammered 5 meters (16 feet) down into the surface. These measurements will be used to determine the temperature of the interior. All of these measurements will lend insight (ha!) into the formation and evolution of Mars.

Radar soundings back and forth to an orbiting spacecraft will be used to measure the wobble of Mars on its axis, which in turn is affected by the structure and composition of the core.

The InSight lander is the result of many technical advances. It’s the first lander to pick up and place instrumentation from the top of the lander onto the surface of the object being studied.

The plan is for InSight to place its seismometer on the surface of Mars, then place a heat and wind shield directly on top of the seismometer. The lander needs to make these placements autonomously, something that has never been done before.

In another major technological advance, InSight arrived on the Martian surface through a complex series of steps involving parachutes and retrorockets. The successful operation of these kinds of tools is a pre-requisite for future human exploration. Just InSight's successful landing represents a major step forward in the study of Mars.

 

Insight-on-mars
An artist’s rendition of the InSight lander operating on the surface of Mars. Image Credit: NASA/JPL-Caltech

Discussion questions for students may be wide-ranging:

  • How does this mission connect to earlier discussions about the formation and structure of planets? (Hooray for final exam review!)
  • Why do we care about the structure of Mars? What implications might a study of the geologic properties of Mars have for future Mars exploration?
  • Do you expect the meteorite impacts to be frequent (more than one per day) or rare (less than one per sol)? Why?

And here are some quick “Google It and Think” questions for small groups:

  • How long did it take for this mission to get to Mars? What factors determined this “flight” time?  What challenges would humans face due to this travel time on a trip to Mars?
  • How many spacecraft, rovers, and landers are currently functioning on Mars? Why is Mars a unique target for missions like these?
  • There are three separate stages for the entry, descent, and landing sequence. What are they?  What problems can you think of that might have occurred in each stage? What steps did the engineering team take to make these problems less likely?