Current Events

Current Events: "Not Just A Space Potato": NASA Unveils "Astonishing" Details of Most Distant Object Ever Visited

By Stacy Palen

According to this article on The Guardian, when the New Horizons spacecraft arrived at Arrokoth, it revealed a surprising world. Now, planetary scientists are beginning to reconsider their conclusions about the formation of the Solar System. This new discovery appears to favor a gentler model of planet formation than the hierarchical model.

Here are some questions, inspired by the arrival of the New Horizons probe at Arrokoth, that you can ask your students:

1) Where is Arrokoth located?

Answer: In the Kuiper Belt.

2) Why can observations of Arrokoth yield information about the early Solar System?

Answer: Objects in the Kuiper Belt remain essentially unchanged since the Solar System formed. They do not have the same history of impacts and geologic processes as objects in the inner Solar System.

3) In your own words, state the hierarchical model of planet formation.

Answer: Small bodies smash together to form progressively larger bodies.

4) In your own words, state the cloud collapse theory of planet formation.

Answer: Slightly denser regions of dust and gas clump together and then, all at once, collapse under gravity.

5) What would astronomers expect Arrokoth to look like if the hierarchical model is correct?

Answer: They would expect to see evidence of collisions, like fractures and varied composition across the body.

6) What would astronomers expect Arrokoth to look like if the cloud collapse theory is correct?

Answer: They would expect to see uniform composition and no evidence of smashing.

7) Which model of planetary formation is supported by the actual appearance of Arrokoth?

Answer: Because Arrokoth is relatively smooth and uniform, it supports the cloud collapse theory of planet formation.


Current Events: 7 billion-year-old stardust is the oldest stuff on Earth

By Stacy Palen

I recently stumbled upon this article from The Washington Post about stardust on Earth. Mineral dust in the Murchison meteorite shows traces of neon produced by cosmic rays as the dust traveled through space. The abundance of neon atoms indicates that the dust was formed 7 billion years ago—before the Sun formed.

Here are some questions to ask your students based on the article:

1) What produces neon atoms in grains of interstellar dust?

Answer: Cosmic rays smash into the grain and convert silicon into neon.

 

2) How does the rate of cosmic rays striking the dust change with time?

Answer: It doesn’t. This rate is constant.

 

3) Suppose that one grain of dust has twice as much neon as another grain. What can you conclude about the relative time each grain spent in space?

Answer: The one with twice as much neon was out there twice as long.

 

4) In your own words, describe how astronomers determine the age of a grain of interstellar dust.

Answer: Astronomers count the number of neon atoms and compare that number to the number of neon atoms in a grain of known age. If there are more neon atoms, the dust grain was roaming the galaxy longer.

 

5) How old is the Sun, and how do we know?

Answer: The Sun is about 4.5 billion years old. We know this from measuring isotope abundances in moon rocks.

 

6) Are these dust grains older or younger than the Solar System?

Answer: These dust grains are 2.5 billion years older than the Solar System.

 

7) Is this result consistent with the idea that stars recycle material from the interstellar medium when they form? Explain.

Answer: Yes! Because the Sun and planets formed from material lost from earlier stars (we know this because of the abundance of other materials. Some of that material is still floating in the Solar System, and some of it was lost from stars that died long before the Solar System formed.


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

Sun nasa pic_12_20_2019
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

201306230004HQ_orig
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