Physics in Your World Features

Astronomy Picture of the Day: Neutrinos in the Sun

Sat, 01 Jun 2013 00:00:00 EST

This image of the sun was made with neutrinos, which are tiny, almost-massless particles that move at nearly the speed of light. Neutrinos are created in nuclear reactions, and were first detected near a nuclear reactor. The nuclear reactions that power the sun produce lots of neutrinos. In fact, billions of them per second are passing through your hand right now. For more about the image, see Astronomy Picture of the Day: Neutrinos in the Sun. To learn how the measurement of solar neutrinos led to a change in fundamental physics, check out this PBS webpage.

NASA Finds Thickest Parts of Arctic Ice Cap Melting Faster

Wed, 01 May 2013 00:00:00 EST

The bright white region near the center of the image shows the year-round Arctic ice in 2012. To see the startling decrease since 1980, visit NASA Finds Thickest Parts of Arctic Ice Cap Melting Faster and slide the white line in the middle of the image to the right.

Sun

Mon, 01 Apr 2013 00:00:00 EST

You are looking at the sun, imaged in extreme ultraviolet light (invisible to us) and shown in false color. To learn more about the sun, visit this this National Geographic article, and also this Hyperphysics page. Notice how irregular the edge of the sun looks. Hot matter streams from the surface and returns, or occasionally some breaks off and heads out into the solar system. See From Physics Research for more information on this matter and how it moves. This image was captured by NASA's Solar Dynamics Observatory on March 26, 2013. (This feature was updated on April 9, 2013.)

Liquid Drop Art

Fri, 01 Feb 2013 00:00:00 EST

This image was created by photographer Corrie White in her basement workshop. She uses a device a device that releases several drops from the same location in rapid succession, at predetermined time intervals. For more of work, see Liquid Drop Art. To learn about the image, see this commentary by a physicist. To see how Corrie does it, check out her illustrated Drop Photography Guide on Flickr.

Atmospheric Optics: Aurora, Northern Lights

Tue, 01 Jan 2013 00:00:00 EST

This image shows a view of the Aurora Borealis captured from the International Space Station as it flew over Nebraska. For more information, see NASA Image of the Day Gallery. For a video of an aurora over the Indian Ocean, visit Aurora from ISS orbit. To find out more about auroras, visit this Atmospheric Optics page and also the Exploratorium’s Auroras: Paintings in the Sky.

Astronomy Picture of the Day: To Fly Free in Space

Sat, 01 Dec 2012 00:00:00 EST

This is astronaut Bruce McCandless, orbiting along with the Space Shuttle in 1984 as he tests his rocket pack. When he stepped outside to begin his spacewalk, why didn’t he fall back to Earth? He stayed in orbit because before and after he stepped outside, McCandless and the Shuttle had the same velocity. The force of Earth’s gravity bent his path into the same orbit as the shuttle; that's because the acceleration of gravity does not depend on the mass of the object being accelerated. To learn more about McCandless’ spacewalk, see Astronomy Picture of the Day: To Fly Free in Space and Footloose. Now look at the image at the top right of Felix Baumgartner beginning his supersonic skydive. When he stepped out, his balloon had been lifting him slowly in the thin stratospheric air, so his initial velocity was quite small. Gravity then pulled him back to Earth. To learn more about gravitational orbits, visit Satellite Motion.

How does an LCD display work?

Thu, 01 Nov 2012 00:00:00 EST

Take a look at this video to see how a liquid crystal display (LCD) TV screen works. For more information, see this Case Western Reserve page. The molecules of a liquid crystal have a tendency to line up, rather than point in random directions. For more, see these pages from Kent State University and from Simon Fraser University.

Robert J. Lang Origami

Mon, 01 Oct 2012 00:00:00 EST

Traditional origami is made by folding one square piece of paper, with no cuts allowed. This piece of origami art, Scorpion varileg, Opus 379, was created by physicist Robert Lang, who left his day job to do origami full-time. You can learn about his work on Robert J. Lang Origami; in the "Science" section, you'll see how origami can be applied to problems in engineering and industrial design. For much more on Lang himself, see this New Yorker article.

Mars Science Laboratory--Curiosity Rover

Sat, 01 Sep 2012 00:00:00 EST

As Curiosity executed its complex landing on Mars last August, another NASA probe, the Mars Reconnaissance Orbiter, captured this remarkable image. It shows Curiosity, along with its parachute, descending toward the surface. The magnified view on the right has been processed to show the details of the parachute--that's why the surface of Mars looks so dark. To learn more about this image, click here. Since the Martian atmosphere is thin, the parachute could not slow Curiosity down enough to land safely. Retrorockets fired, and while they were still firing, the Rover was lowered to the surface by cables. Once Curiosity was on the ground, the cables were cut. For a NASA simulation of Curiosity's landing, see Seven Minutes of Terror. And to watch the Jet Propulsion Laboratory mission controllers during the landing, don't miss control room reactions. To see the parts of the Curiosity spread out on the Martian surface, click on this JPL image. For more images, videos, and much more, visit Mars Science Laboratory--Curiosity Rover.

Impact Cratering

Wed, 01 Aug 2012 00:00:00 EST

The Galileo spacecraft captured this image as it passed by the moon on its way to Jupiter. See the smooth dark areas? They were created three to four billion years ago when large volcanoes erupted and lava filled in the low-lying regions. Most of the smooth dark areas are round--these started off as enormous craters. Later, volcanoes erupted and filled them in, producing "impact basins." To find out more about how impact basins were formed, visit Impact Cratering. In the right half of the image above, look at the region close to the edge of the shadow, where the craters stand out most clearly (that's because the angle of the sun is low). Note how the whitish regions of the moon are almost completely filled with craters, whereas the smooth, dark areas have very few. For a possible explanation, called the "late heavy bombardment," visit NASA's The Solar System’s Big Bang.

The Oklo Fossil Fission Reactors

Sun, 01 Jul 2012 00:00:00 EST

This photo shows part of a natural nuclear reactor-- an underground uranium deposit where a chain reaction occurred spontaneously. In fact, such a natural reactor was predicted, beginning in 1956, and then discovered in 1972. To find the reactor, physicists search for a deposit of uranium with a slightly lower concentration of U-235 than is found elsewhere on Earth. This U-235 deficit would be caused by the chain reaction of a small fraction of the U-235 nuclei. To learn more, visit The Oklo Fossil Fission Reactors and also this Astronomy Picture of the Day page.

Hyperphysics: Electric Guitars

Fri, 01 Jun 2012 00:00:00 EST

This photo shows the electric guitar pickups from a Fender Stratocaster. Notice that there are three different pickup locations, and each location has a pickup (the circular dots) for every string. Each individual pickup contains a magnet, a coil, and thousands of turns of insulated wire wrapped around the magnet. To find out how an electric guitar produces sound from a vibrating string, see Hyperphysics: Electric Guitars. To learn about the physics of vibrating strings, see this additional Hyperphysics page.

Hyperphysics: Torque

Tue, 01 May 2012 00:00:00 EST

Think about the forces on this sailboat: The force of the wind on the sail (perpendicular to the fabric of the sail), tends to rotate the boat. A force that can rotate an object is called a torque. In this case, if the torque of the wind isn't balanced, it will tip the boat over. The weight of the sailor, and also the weight of the hull that's out of the water, both create torques in the opposite sense, to balance the torque of the wind. For more on torques, see Hyperphysics: Torque, and also this other Hyperphysics page.

Hyperphysics: Electromagnetic Waves

Sun, 01 Apr 2012 00:00:00 EST

In the photo above of a handheld citizens band radio, the metal coil is the antenna. When the radio is transmitting, the radio produces an electric current that surges back and forth in the antenna, which emits radio waves. And when the radio is receiving, radio waves induce a tiny alternating current in the antenna. The current in the antenna carries the radio signal. For a drawing of an electromagnetic wave (radio waves are one example) see Hyperphysics: Electromagnetic Waves. To learn more about the CB antenna shown in the photo, go to this Wikipedia article and scroll down.

Structure and Optical Isomerism

Thu, 01 Mar 2012 00:00:00 EST

Have you noticed that the left hand is the mirror image of the right hand, but they cannot be superimposed? That's also true for some molecules containing carbon atoms. In the image above, the molecule on the left cannot be superimposed on the one on the right. To learn more about such molecules, check out Structure and Optical Isomerism; also, click to see this movie. Such left-handed and right-handed molecules rotate the plane of polarization of light in opposite directions. To find out more about polarized light and this important effect, click here. Also, you can learn how Louis Pasteur explained it.

Kepler Mission

Wed, 01 Feb 2012 00:00:00 EST

The NASA Kepler observatory searches for extrasolar planets by monitoring about 100,000 stars in a small patch of sky. The observatory looks for stars that periodically dim as a planet passes in front of the star. Kepler was launched in 2009, and by January, 2012, it had already found 33 confirmed extrasolar planets and about 2300 candidates. To learn more, visit Kepler Mission, then click on "About the Mission."

How Things Work: Winglets

Sun, 01 Jan 2012 00:00:00 EST

The photo shows two NASA F/A18s. The smoke streaming from the wingtip of the one on the right reveals the wingtip vortex, which increases the wing’s drag. This vortex occurs because the pressure underneath the wing is greater than the pressure above the wing; this excess pressure generates a flow of air around the wingtip, creating the vortex. These vortices can trail behind the aircraft for miles, creating a hazard for following aircraft, particularly small ones. To reduce the drag caused by these vortices, "winglets" have been added to the wingtips of some airliners, as you can see in this Wikimedia photo. To learn more, visit How Things Work: Winglets.

Ferrofluids

Thu, 01 Dec 2011 00:00:00 EST

Physics becomes art in Felice Frankel's photo of a ferrofluid with permanent magnets underneath. In a ferrofluid, a region of approximately constant magnetic field produces a pattern of spikes. A ferrofluid is a concentrated suspension of nanometer-sized magnetic particles. To learn more, see the Physics Central feature Ferrofluid Fun and also the videos at Ferrofluids.

Relativity Powers Your Car Battery

Tue, 01 Nov 2011 00:00:00 EST

If you own a car with a lead-acid battery, you might be interested to know that 80% of the voltage comes from Einstein's theory of special relativity. Lead works so well in storage batteries because its atom has a large nucleus, and the innermost electrons rotate at a significant fraction of the speed of light, bringing relativity into play. To learn more, visit Physical Review Focus' Relativity Powers Your Car Battery. For more on the special theory of relativity, visit this Stanford site.

What is a contrail and how does it form?

Sat, 01 Oct 2011 00:00:00 EST

The contrails in the photo above were generated by an Air Force C-141 Starlifter. Jet fuel is a mixture of hydrocarbons, which burns to produce carbon dioxide and water vapor. The water vapor condenses upon cooling to form small water droplets--the contrail--which is essentially a cloud. To learn more, check out What is a contrail and how does it form? from the National Weather Service. Like clouds, contrails can affect global warming--to find out how, see From Physics Research and Worth a Look.

HyperPhysics: Global Positioning Satellites

Thu, 01 Sep 2011 00:00:00 EST

The image shows a Global Positioning System (GPS) receiver that pinpoints a cyclist's location to an accuracy of about 10 m. The receiver analyzes radio signals from several GPS satellites, each containing an atomic clock accurate to about one second every 30,000 years. For more on GPS, see HyperPhysics: Global Positioning Satellites and also this NASA site.

Nonlinear Geoscience: Fractals

Tue, 02 Aug 2011 00:00:00 EST

Look up at the clouds and look at the patterns you see. It turns out that if you zoom in or out, you still see the same patterns, a property mathematicians call self-similarity. In Nonlinear Geoscience: Fractals, notice how the streambed in the photograph has divided again and again, showing the same structure at different scales. The streambed and the sky are only two examples of the many fractals found in nature.

What is Microgravity?

Fri, 01 Jul 2011 00:00:00 EST

The photo shows astronauts training in a NASA plane that flies in a parabolic arc—the same path a projectile follows—so they can experience free fall, just as they will in space. To find out what these flights are like, check out the Reduced Gravity: Vomit Comet Blog from the American Physical Society's Physics Central. To learn about gravity in space, see the first page of Fluids in Space, also from Physics Central, and What is Microgravity? (but don't be fooled by the title—there is plenty of gravity in space around the Earth, and it keeps satellites in their orbits).

Chaotic Pendulum

Wed, 08 Jun 2011 00:00:00 EST

The photo above shows a three-way double pendulum at the Exploratorium, and you can see a video about this exhibit at Chaotic Pendulum. (A double pendulum is essentially one pendulum hung underneath of another--see this diagram.) In general, the motion of this pendulum is chaotic.

Fiestaware

Thu, 12 May 2011 00:00:00 EST

The distinctive color of orange-red Fiestaware, which was popular in the 1930s and 1940s, is produced by uranium oxide in the glaze. For more information, see Fiestaware, and for a list of similar items, see Radioactive Consumer Products (the two websites referenced here are from Oak Ridge Associated Universities).