On the evening of March 6, 2019, the Moon started to transit the Sun, then doubled back and retraced its steps in the other direction -- at least, that's what it looked like from the perspective of NASA's Solar Dynamics Observatory, or SDO, in orbit around Earth.
SDO sees lunar transits regularly, when the Moon passes in front of its view of the Sun. The Moon's unusual apparent behavior during this particular transit is a phenomenon similar to retrograde motion: When a celestial object appears to move backwards because of the way that different objects move at different speeds at different points in their orbits.
The relative speeds and positions of the Moon, the Sun and NASA's Solar Dynamics Observatory resulted in this unusual lunar transit where the Moon appears to pause and reverse course. View animated GIF: https://www.nasa.gov/sites/default/files/thumbnails/image/171transitslowpause3.gif
NASA's Solar Dynamics Observatory spotted a lunar transit just as it began the transition to the dusk phase of its orbit, leading to the Moon's apparent pause and change of direction during the transit. This animation (with orbits to scale) illustrates the movement of the Moon, its shadow and SDO. View animated GIF: https://www.nasa.gov/sites/default/files/thumbnails/image/lunartransit2.gif
In this case, the first part of the transit -- when the Moon moves left to right -- appears to be "reverse" motion. SDO overtakes the Moon, moving at about 1.9 miles per second perpendicular to the Sun-Earth line compared to the Moon's 0.6 miles per second, making the Moon appear to move in the opposite direction you would see if you were standing still on Earth.
The second part of the transit -- when the Moon appears to pause and rewind -- happens as SDO enters the dusk part of its orbit and begins moving away from the Moon, nearly parallel to the shadow it's casting through space.
At that point, the Moon once again moves faster than SDO - when compared to the Sun-Earth line - overtaking it. So the spacecraft now sees it move in the other direction -- the same direction that a stationary observer on Earth would see.
This isn't the first time that SDO has seen the Moon seem to move in two different directions during a lunar transit. This time, the Moon just happened to remain in SDO's sight as it began the dusk part of its orbit, leading to the freeze-frame effect.
This lunar transit lasted about four hours, from 5 p.m. to 9:07 p.m. EST, and, at peak, the Moon covered 82 percent of the Sun's face. The Moon's edge appears sharp because the Moon has no atmosphere.
On the other hand, Earth eclipses of the Sun have a blurry edge when seen by SDO, because the gases in Earth's atmosphere let through only part of the Sun's light.
Sarah Frazier | EurekAlert!
Hamburg and Kiel researchers observe spontaneous occurrence of skyrmions in atomically thin cobalt films
23.08.2019 | Universität Hamburg
Building an atomic-scale vacuum trap for spin-polarized electrons
23.08.2019 | University of Hamburg Sonderforschungsbereich 668
Since their experimental discovery, magnetic skyrmions - tiny magnetic knots - have moved into the focus of research. Scientists from Hamburg and Kiel have now been able to show that individual magnetic skyrmions with a diameter of only a few nanometres can be stabilised in magnetic metal films even without an external magnetic field. They report on their discovery in the journal Nature Communications.
The existence of magnetic skyrmions as particle-like objects was predicted 30 years ago by theoretical physicists, but could only be proven experimentally in...
Theoretical physicists at Trinity College Dublin are among an international collaboration that has built the world's smallest engine - which, as a single calcium ion, is approximately ten billion times smaller than a car engine.
Work performed by Professor John Goold's QuSys group in Trinity's School of Physics describes the science behind this tiny motor.
Together with the University of Innsbruck, the ETH Zurich and Interactive Fully Electrical Vehicles SRL, Infineon Austria is researching specific questions on the commercial use of quantum computers. With new innovations in design and manufacturing, the partners from universities and industry want to develop affordable components for quantum computers.
Ion traps have proven to be a very successful technology for the control and manipulation of quantum particles. Today, they form the heart of the first...
Experimental progress towards engineering quantized gauge fields coupled to ultracold matter promises a versatile platform to tackle problems ranging from condensed-matter to high-energy physics
The interaction between fields and matter is a recurring theme throughout physics. Classical cases such as the trajectories of one celestial body moving in the...
Soft robots have a distinct advantage over their rigid forebears: they can adapt to complex environments, handle fragile objects and interact safely with humans. Made from silicone, rubber or other stretchable polymers, they are ideal for use in rehabilitation exoskeletons and robotic clothing. Soft bio-inspired robots could one day be deployed to explore remote or dangerous environments.
Most soft robots are actuated by rigid, noisy pumps that push fluids into the machines' moving parts. Because they are connected to these bulky pumps by tubes,...
16.08.2019 | Event News
14.08.2019 | Event News
12.08.2019 | Event News
23.08.2019 | Life Sciences
23.08.2019 | Information Technology
23.08.2019 | Life Sciences