This week we’re taking a look at an ever-popular demonstration of the laws of motion: Free Fall in Vacuum. You can see it presented in this new video starring Logan Anbinder.

A heavy disc and a lightweight feather are contained in a long glass tube. While the tube is full of air, when you flip it over the disc drops quickly to the bottom, and the feather floats slowly downwards. Once most of the air has been pumped out, however, the two fall together and hit the bottom at the same time.

When no other forces interfere, the two objects experience the same acceleration from gravity. While there is air in the tube, however, air resistance slows both objects, but the feather more so than the disc due to its lighter mass compared to its surface area. This is an excellent example of why, when solving physics problems, we need to identify all of the forces involved in a system and determine their effects.

This demonstration is a classic way of explaining the nature of free fall and gravitational acceleration. Perhaps one of the most dramatic presentations of it came in 1971 when astronaut David Scott carried out this experiment with a hammer and feather on the Moon! Without air, the feather and hammer dropped together to the lunar soil. You can see the video in a NASA archive website here, hosted by Goddard Space Flight Center: https://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_15_feather_drop.html 

Demonstration P4-04, the Cosmic Ray Detector, has recently been upgraded. PhD student Liz Friedman shows it in action in this video.

When energetic particles from space hit the upper atmosphere, they create a cascade of particles in the air around us. Even a single cosmic ray might create a whole shower of particles in our atmosphere. They’re invisible, but with the right apparatus we can detect them. Each of the two dark blocks in this device is a scintillator. When a particle passes through one scintillator, it makes a tiny spark of light, which is picked up by a sensitive photodetector. By checking for correlations between the two paddles, we can spot which sparks are being caused by particles passing straight through from space.

These particles stream around and through us all the time, harmlessly; but it’s pretty amazing that we can build a tabletop device that can measure them!

You can read more about Liz’s adventures in physics, hunting neutrinos in Antarctica, in last summer’s Odyssey magazine https://cmns.umd.edu/news-events/features/4642

Today marks the 100^th birthday of NASA scientist Katherine Coleman Johnson. For decades, she was one of the leading minds of NASA’s space navigation program, plotting courses of the Mercury, Apollo, and Shuttle programs, including both the 1969 Apollo 11 moon landing and the 1970 recovery course of the aborted Apollo 13.

Born in rural West Virginia in 1918, a career in mathematics and physics was not an easy course for a young African-American woman. She faced massive discrimination on all sides, but demanded her place in the technical community. She joined the staff of the National Advisory Committee for Aeronautics (NACA) in 1953 as a computer, and stayed on through multiple technical posts as the organization became NASA, the National Aeronautics and Space Administration. in 1958.She contributed to many of the major space missions of the time, and had a reputation as the most best mathenatician on the team. For his 1962 solo orbital mission, then-astronaut (and later Senator) John Glenn refused to go into orbit without Johnson plotting his navigation before he stepped aboard.

A partial bibliography of her technical publications can be found on her NASA History page at https://crgis.ndc.nasa.gov/historic/Katherine_Johnson . Johnson retired from NASA in 1986, but resides in Hampton, Virginia near Langley Research Center to this day.

In recent years, Johnson and her compatriots have begun to receive greater recognition for their work. The 2016 book and film Hidden Figures helped to bring public attention to the computational work behind many famous space missions. A new research center at NASA Langley was named for Johnson [https://www.nasa.gov/image-feature/langley/nasa-celebrates-katherine-johnson-with-building-named-in-her-honor], and last week West Virginia University unveiled a statue of her and launched a scholarship fund in her name in recognition of her studies in the state and her struggle against segregation and sexism. [https://www.wvgazettemail.com/news/katherine-johnson-immortalized-with-statue-on-wv-state-university-campus/article_faaaff7b-e452-5de5-8612-892a64a514bd.html]

 As we begin the new school year, this is an excellent opportunity to think about how we can teach our students more about the history and diversity of our field, and the different paths we can all take in our careers.

Links:

NASA celebration of Katherine Johnson’s 100^th birthday, and resources for educators:

https://www.youtube.com/watch?v=_ERy7-Pd0dU

https://www.nasa.gov/audience/foreducators/a-lifetime-of-stem.html

Official NASA biography of Katherine Johnson, by Margot Lee Shetterly: https://www.nasa.gov/content/katherine-johnson-biography

The Newport News Daily Press on Johnson’s 100^th birthday: http://www.dailypress.com/news/science/100708055-132.html

Beyond Curie, resources for educating about women in science: Katherine Johnson https://www.beyondcurie.com/katherine-johnson/

Mental Floss: 9 Fascinating Facts about Katherine Johnson http://mentalfloss.com/article/555114/facts-about-katherine-johnson-nasa

This week marks the birthday of the late scientist and science educator Carl Sagan, born in 1934. Sagan is best remembered today for his work popularizing and communicating science, particularly with his several books and his popular television program Cosmos.

Less well known these days, however, is his professional work as an astrophysicist studying planetary atmospheres. He contributed to early work establishing surface conditions on Venus, extrapolating pressure and temperature ranges from radar reflectivity data. He likewise studied atmospheric flow on Earth, Mars, Jupiter, and the trace gases of the Galilean moons.

In conjunction with his science education work, he went on to extrapolate from this and argued convincingly of the potential perils of climate change on Earth as well, as reflected in the more extreme changes on Venus.

But in the end, his most crucial contribution was as an educator and communicator of science, bringing his joy and fascination with scientific discovery to the masses, and inspiring many young people to follow his path into the sciences.

 Some of Sagan's early work:

Sagan, C. (1961). The planet Venus. Science, 133(3456), 849-858.

Sagan, C. (1962). Structure of the lower atmosphere of Venus. Icarus, 1(1-6), 151-169.

Sagan, C., & Pollack, J. B. (1967). Anisotropic nonconservative scattering and the clouds of Venus. Journal of Geophysical Research, 72(2), 469-477.

Sagan, C., & Veverka, J. (1971). The microwave spectrum of Mars: An analysis. Icarus, 14(2), 222-234.

Sagan, C., & Mullen, G. (1972). The Jupiter greenhouse. Icarus, 16(2), 397-400.

Sagan, C., & Mullen, G. (1972). Earth and Mars: Evolution of atmospheres and surface temperatures. Science, 177(4043), 52-56.

Sagan, C., Toon, O. B., & Gierasch, P. J. (1973). Climatic change on Mars. Science, 181(4104), 1045-1049.

Sagan, C. (1975). Windblown dust on Venus. Journal of the Atmospheric Sciences, 32(6), 1079-1083.

Sagan, C., & Bagnold, R. A. (1975). Fluid transport on Earth and aeolian transport on Mars. Icarus, 26(2), 209-218.

Smith, B. A., Soderblom, L. A., Johnson, T. V., Ingersoll, A. P., Collins, S. A., Shoemaker, E. M.,... & Cook, A. F. (1979). The Jupiter system through the eyes of Voyager 1. Science, 204(4396), 951-972.

SMITH, B. A., Soderblom, L. A., Beebe, R., Boyce, J., Briggs, G., Carr, M.,... & Hunt, G. E. (1979). The Galilean satellites and Jupiter: Voyager 2 imaging science results. Science, 206(4421), 927-950.

Squyres, S. W., Buratti, B., Veverka, J., & Sagan, C. (1984). Voyager photometry of Iapetus. Icarus, 59(3), 426-435.

Sagan, Carl, et al. "Polycyclic aromatic hydrocarbons in the atmospheres of Titan and Jupiter." The Astrophysical Journal 414 (1993): 399-405.

https://en.wikipedia.org/wiki/Carl_Sagan

NASA announced last month that their upcoming infrared observatory project had been named the Nancy Grace Roman Space Telescope. Today, we’re going to take a brief look at this project, Dr. Roman, and the role of physics in astronomy.

Nancy Grace Roman (1925-2018) was the first Chief of Astronomy for NASA, and the first woman ever to hold an executive-level position there. A graduate of Western High School in Baltimore, and later of Swarthmore College and the University of Chicago, she began her career in astronomy research specializing in the emission spectra of stars.

Spectroscopy is the study of the spectrum of light, the individual frequencies and colors that make up the light we see. Every element and compound emits its own distinctive pattern of frequencies of light, based on the structure and energy of the electrons within the atom. By analyzing the light from stars, we can use these distinctive patterns as a kind of fingerprint to identify the chemical makeup of distant stars and planets. Our demonstration collection at UMD Physics has many demonstrations about spectra and spectroscopy; be sure to click here and check them out!

 Not all light is visible to our eyes; lower frequency light is below the range that we can see, in infrared wavelengths. Space telescopes are often valuable for observing this invisible light without interference from our atmosphere, just as they are in the visible spectrum.

Despite her skill as a researcher, the widespread discrimination against women in the sciences made it difficult for Dr. Roman to advance her career in academia. Eventually, she moved to working in government instead, first joining the Naval Research Laboatory and then NASA. She essentially created the astronomical science program at NASA, plotting its course for decades to come. She was a key player in the development of many of NASA’s research satellites, including Uhuru, the first X-ray astronomy satellite; and she was a leader in the creation of the Hubble Space Telescope. She advocated that NASA science should be for everyone, and ensured that their research and data were publicly available.

Dr. Roman retired from NASA, and began a second career in scientific computing. She learned programming at Montgomery College and went on to work as a contractor specializing in scientific data management, eventually returning to NASA as a contractor to manage the Astronomical Data Center at Goddard Space Flight Center.

 Dr. Roman worked hard to inspire more women to become scientists and leaders in science, and we can hope to follow in her footsteps.

 The recipients of the 2020 Nobel Prize in Physics were announced this morning. This year, the prize has been awarded for discoveries related to black holes. The recipients: Reinhard Genzel, Andrea Ghez, and Roger Penrose.

Black holes are a phenomenon predicted by the theory of relativity, that a sufficiently massive object could have enough gravity to warp spacetime such that even light could not escape from it. Roger Penrose carried out some of the important theoretical calculations establishing the reality and properties of black holes; Andrea Ghez and Reinhard Genzel led experiments that established that a supermassive black hole exists at the center of our own Milky Way galaxy.

Reinhard Genzel made a virtual visit to UMD last month as the speaker for the Astronomy Colloquium; he is director of Germany’s Max Planck Institute for Extraterrestrial Physics and is also a professor at the University of California, Berkeley.

Andrea Ghez is a professor of physics and astronomy at the University of California, Los Angeles. She and her research were featured in a NOVA television special on black holes in 2018. She won the APS Maria Goeppert Mayer Award in 1999.

Roger Penrose is a professor at the University of Oxford. In 1988 he shared the Wolf Prize in Mathematics with Stephen Hawking for their mathematical research regarding spacetime singularities.

We’ll share more information on black hole physics in an upcoming post; meanwhile, check out these links for more about the physics, the people, and the prize.

 Read More:

• Nobel Prize in Physics homepage https://www.nobelprize.org/prizes/physics/\

• Nobel Prize 2020 Resources from AIP https://www.aip.org/science-news/nobel2020

• NASA’s Hubblesite: What Are Black Holes? https://hubblesite.org/contents/articles/black-holes.html

• Interview this morning with Andrea Ghez https://www.youtube.com/watch?v=VNUJ8Uknv-M 

• Update: Physics Today: "Nobel Prize in Physics honors research on black holes": "Nobel Prize in Physics honors research on black holes"

• Update: APS Physics: Nobel Prize: Facing the Reality of Black Holes 

• Articles by Roger Penrose now free to read: 1963's Asymptotic Properties of Fields and Space-Times and1965's Gravitational Collapse and Space-Time Singularities 

• Explore our growing directory of relativity & gravitation simulations

We’ve had some big events this past month on our usually-quiet moon. India’s Chandrayaan-3 probe made a successful soft landing at the lunar south pole, the first ever to achieve such a landing in this region. The probe and the rover it carries will be carrying out scientific surveys of the area.

Meanwhile, Russia’s Luna-25 probe attempted a similar landing this month but crashed due to a malfunction during an orbital burn.

A followup mission, Luna-26, is planned for 2027.

Read more at Scientific American:

• Chandrayaan-3 Makes Historic Touchdown on the Moon
• Russia’s Luna-25 Lander Has Crashed into the Moon

UPDATE 1 December 9AM: The structure did not survive the night. https://www.sciencemag.org/news/2020/12/arecibo-telescope-collapses-ending-57-year-run 

The radiotelescope at Arecibo Observatory will be shut down and dismantled, the National Science Foundation determined this month. Arecibo has contributed to astronomical research ranging from the planetary to the extragalactic scale for over 50 years. Recent damage from storms and aging appears unrepairable, and NSF now plans for its careful disassembly for safety reasons.

Read more:

•  Physics Today https://physicstoday.scitation.org/do/10.1063/PT.6.2.20201124a/full/
•  Arecibo Observatory home page http://www.naic.edu/
•  NSF Press Release https://www.nsf.gov/news/news_summ.jsp?cntn_id=301674
• Follow updates at the International Asteroid Warning Network http://iawn.astro.umd.edu/ 

A new comet has been spotted! The newly discovered C/2021 A1 (Leonard) is colloquially called Comet Leonard after its discoverer G. J. Leonard, who was observing at the Mount Lemmon Observatory in Arizona. C/2021 A1 is a hyperbolic comet, expected to be ejected from the Solar System after its pass near the sun later this year. But in the meantime, it will have an exciting existence, and may provide for some interesting viewing!

C/2021 A1’s closest approach to the Earth will be on December 12 of this year, and it will make its final pass closest to the sun just after the New Year, on January 3 of 2022. Depending on how it is affected by the space environment, it may become visible to the naked eye this coming winter; even if not, it should be spottable with simple optical instrumentation.

• Read more at EarthSky.org

Observational Data:

• C/2021 A1 at the IAU’s Minor Planet Center

• C/2021 A1 at JPL’s Small-Body Database

A recently discovered comet may be (barely) visible over the coming days. Comet C/2023 P1, discovered by amateur astronomer Hideo Nishimura, is making its closest approach in the next week. Current estimates of its orbital period are several hundred years, so we won’t likely get a chance to see this again soon, if at all!

Read more:
Scientific American: https://www.scientificamerican.com/article/watch-a-comets-tail-get-mangled-by-the-sun/
EarthSky: https://earthsky.org/tonight/new-comet-c-2023-p1-nishimura-bright-august-september-october-2023/
JPL Small-Body Database: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=C%2F2023%20P1

Keep your eyes on the sky for the next few weeks, because we have a visitor. Comet C/2022 E3 (ZTF) was discovered last year by Palomar Observatory’s Zwicky Transient Facility (hence the name). Its orbit will bring it on its closest approach to the sun next week, and its closest approach to Earth at the beginning of February.

Right now, the comet can only be seen with a telescope; but by its closest approach, may be visible in the early morning sky with just a pair of binoculars.

Read More:

• NASA announcement https://science.nasa.gov/comet-2022-e3-ztf

• NASA Small Body Database https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1003845

• Wikipedia https://en.wikipedia.org/wiki/C/2022_E3_(ZTF)

• EarthSky https://earthsky.org/astronomy-essentials/new-comet-might-get-bright-enough-for-binoculars/

• Space.com https://www.space.com/comet-2022-e3-ztf-possible-naked-eye-visibility-2023

June 23-29 will be the virtual Earth Observation Dashboard Hackathon, jointly sponsored by NASA, ESA, and JAXA. Teams will work on coding challenges related to Earth & climate data and the COVID-19 pandemic. Projects include studying air and water quality changes, economic and agricultural impacts of the pandemic, and data visualization.

Learn more and register at https://www.eodashboardhackathon.org/

An exoplanet candidate has been identified orbiting a white dwarf for the first time. Vanderberg et al reported this month in Nature that a planetary-sized body has been identified orbiting WD 1856+534 (TIC 267574918) with a period of 1.4 Earth days, based on periodic transit dimming in the infrared range. This suggests, surprisingly, that the planetary body survived the star’s explosion and transition to white dwarf status.

Read more:

• Lopatka, A. New exoplanet endured a rough start. Physics Today (16 September 2020). https://physicstoday.scitation.org/do/10.1063/PT.6.1.20200916b/full/

• Vanderburg, A., Rappaport, S.A., Xu, S. et al. A giant planet candidate transiting a white dwarf. Nature 585, 363–367 (2020).  https://doi.org/10.1038/s41586-020-2713-y

• Vieser, W. Hunting for Exoplanets. Science in School 49 (2020). https://www.scienceinschool.org/content/hunting-exoplanets

As we’ve reported recently, there is a lot happening on Mars right now! The US and China have both landed rovers on Mars, and the UAE has a new Martian orbiter as well, all carrying out scientific observations. You can follow along with the latest online with some of the links below.

 Meanwhile, March also offers a good opportunity to see the planet Mars in the sky for yourself. Mars appears in the evening sky right now, and this week you can see it in conjunction with the Pleiades star cluster. This is their closest conjunction in 20 years, and the closest they’ll be in the sky again until 2038. Of course, Mars is nowhere near the Pleiades in space, it’s practically our next-door neighbor; but the conjunction makes for a spectacular light show in the sky.

 The Pleiades are cluster of young, bright stars over 400 light years away. They’re often referred to as the “Seven Sisters,” although there are more than seven of them – in a dark sky with clear air you might be able to pick out a dozen separate points of light with your eye, and telescopes have spotted hundreds of dimmer ones adding to the mass of the cluster.

 Also, if you’re out in the early morning this month, keep an eye out for three other bright spots: Mercury, Jupiter, and Saturn may all be visible low on the horizon near sunrise. Read more at EarthSky.org.

 And remember to watch for the latest news from Mars! Check out these links, and watch for articles tagged "space" here on the blog!

• NASA Mars 2020 

• Emirates Mars Mission

• Mars on Google Maps

• NASM: Mars

• Smithsonian Magazine: Exploring Mars

• Astronomy Magazine: Mars

• Sky&Telescope Magazine: Solar System

•  Eartth&Sky: Mars Observing Tips 

NASA’s Wallops Flight Facility on Wallops Island, Virginia off the Eastern Shore will, weather permitting, be launching a rocket this evening just after 8:00PM. This will carry the KiNET-X experiment, which will release vapor clouds to analyze energy and momentum transfer in nearby space. This will help better understand the behaviour of plasmas in Earth's magnetosphere.

The rocket and the vapor trails may be visible to the east of our campus in the evening sky. Keep an eye out! Or follow along online at the links below.

 Read more:

• NASA Press Release https://www.nasa.gov/wallops/2021/press-release/nasa-wallops-may-8-rocket-launch-visible-in-eastern-united-states
• Wallops Streaming Video https://video.ibm.com/channel/nasa-tv-wallops

This week we expect to see the launch of NASA’s latest mission to Mars! The launch is scheduled for the morning of July 30; see the countdown at undefined . The lander is expected to then touch down on Mars in February 2021.

This is an unusually complex mission, featuring two separate mobile units. The Perseverance rover is a heavier redesign of the previous Curiousity rover, with a similar plutonium-based radiothermal generator for power. In addition, Ingenuity is a new helicopter-style flying drone that is carried by the rover, with an array of sensors and cameras. This is an experimental model; if it works as anticipated more complex aerial units may be added to future missions.

Get ready to watch the launch Thursday, and keep your eyes on the sky!

Further reading:

NASA Mars 2020 mission page

 https://mars.nasa.gov/mars2020/

NASA  video

 https://mars.nasa.gov/mars2020/timeline/launch/watch-online/

Dr. Baranwal of the Department of Energy on the RTG power source for the rover 

Image credit: NASA

The night of Sunday May 15^th and into the morning of Monday May 16^th, a total lunar eclipse will be visible from the UMD neighborhood, and through out much of eastern North America and nearly all of South America.

A total lunar eclipse can only occur during the full moon, when the Earth and Sun line up with the moon at exactly the right orientation and spacing for the Earth’s shadow to completely cover the moon. This is what makes it different from the New Moon we see every month, when from our perspetive the moon is shaded by its own shadow, while the side we can’t see is illuminated – a lunar eclipse occurs on what would then otherwise be the brightly illuminated side of the moon!

 If you’re up late that night (not always recommended during final exams, but sometimes worth it), take a look at the sky and enjoy this stunning astronomical treat.

Read More

• Washington Post https://www.washingtonpost.com/science/2022/04/29/skywatch-late-night-lunar-eclipse-is-coming-mid-may/

• EarthSky https://earthsky.org/astronomy-essentials/total-lunar-eclipse-may16-2022/

• NASA https://solarsystem.nasa.gov/skywatching/whats-up/

And here’s an experiment you can try at home to model how eclipses happen: http://clearinghouse.starnetlibraries.org/astronomy-and-space/140-why-do-eclipses-happen-yardstick-eclipse-demonstration.html

There's a lot happening overhead this week!

The Perseid Meteor Shower is at its peak this week. Meteor showers are a stunning sight in the night sky, and the Perseids are one of the brightest of the year. The sparks of light you see in the sky are the burning debris from past passages of Comet Swift-Tuttle, which passes through the solar system every 133 years... but we pass through its path in August every year! Read more about the Perseids at NASA's Solar System Exploration pages.

Ordinarily, this would not have been the best of years to see the Perseids anyway, since the moon is full, and its bright light would make them hard to see. But it has turned out to be a moot point in our region, as our skies are darkened by a phenomenon much closer to home: Tropical Storm Isaias. This storm has been making its way up the coast and is now dumping quite a lot of rain on us, so everyone please be cautious! These storms can be dramatic to watch, but also potentially dangerous.

Hurricanes and tropical storms are driven by converging winds and moist air over warm water. Climate change in recent years has warmed the waters of the ocean - by only a small amount, but in a large and complex system, a small change in initial conditions can have a dramatic effect on the outcome! You can see this modeled in the classroom with demonstrations like our chaotic pendulum, G1-60; be sure to check out the simulation linked there that lets you experiment with tiny changes in the initial conditions. 

 Keep your eyes on the sky - but be careful out there!

Read more:

National Hurricane Center

NOAA video: Fuel for the Storm

NASA: In Depth on the Perseid Meteor Shower

EarthSky.org: Perseid Meteors 2020

Double Pendulum Simulator by Erik Neumann

The NASA STEM Engagement & Educator Professional Development Collaborative (EPDC) is a program hosted at Texas State to support STEM education and outreach nationwide. They host a wide variety of webinars designed for professional development for educators exploring space science topics. They also offer STEM teaching tips and connections to subject specialists.

Check them out at https://www.txstate-epdc.net/

NASA STEM Stars is a NASA-produced web video chat series featuring a variety of space scientists and professionals introducing their areas of study and careers to a secondary school audience. The past videos are archived on YouTube, and can be a useful resource for a variety of educational purposes.

 The next upcoming chat will be on June 30 with satellite engineer Kenny Harris, who will discuss his work on the James Webb Space Telescope and other space science projects.

Read More:

• NASA STEM Stars website

• NASA STEM Stars playlist on YouTube