Physics & Astronomy News

<p>Schematic view of a bubble implosion, which is an envisioned picture showing the whole main events integrated, i.e., laser illumination, hot electron spread, implosion, and proton flash. (credit/ M. Murakami)</p>
Laser-driven Implosion
Scientists have discovered a novel particle acceleration mechanism called ‘micro-bubble implosion’
<p>Owens Valley Solar Array (EOVSA)</p>
New Insights into Solar Flares
New insights into solar flares' explosive energy releases were released by the Owens Valley Solar Array (EOVSA)

<p>In this illustration, the grid in the background represents the computational lattice that theoretical physicists used to calculate a particle property known as nucleon axial coupling. This property determines how a W boson (white wavy line) interacts with one of the quarks in a neutron (large transparent sphere in foreground), emitting an electron (large arrow) and antineutrino (dotted arrow) in a process called beta decay. This process transforms the neutron into a proton (distant transparent sphere). (Credit: Evan Berkowitz/Jülich Research Center, Lawrence Livermore National Laboratory)</p>
Life and Death of a Neutron
Experiments that measure the lifetime of neutrons reveal a perplexing and unresolved discrepancy.
<p>Precision assembly and mechanical technician Ryan Wilkinson inspects MOMA during thermal vacuum testing at Goddard</p>

<p>Credits: NASA</p>
Looking for Signs Life on Mars
Scientists have created a tiny chemistry lab for a rover that will drill beneath the Martian surface looking for signs of past or present life.

Massive Black Hole Devours a Star
Scientist create new models of Tidal Disruption Events - rare, but extremely forceful events taking place in the center of galaxies.
Dark Matter Limit Established
Experimental results from the XENON1T dark matter detector limit the effective size of dark matter particles to 4.1X10-47 square centimeters.
Water is not the same as water
Researchers have succeeded in separating the two forms of water to show that they can exhibit different chemical reactivities.

Science Facts

Magnitude of an Astronomical Object

by NASA Marshall Space Flight Center and

: Image Courtesy Science@NASA 'Visual magnitude' is a scale used by astronomers to measure the brightness of a star. The term 'visual' means the brightness is being measured in the visible part of the spectrum, the part you can see with your eye (usually around 5500 angstroms). The first known catalogue of stars was made by the Greek Astronomer Hipparchus in about 120 B.C. and contained 1080 stars. It was later edited and increased to 1022 stars by Ptolemy in a famous catalogue known as the 'Almagest'. Hipparchus listed the stars that could be seen in each constellation, described their positions, and rated their brightness on a scale of 1 to 6, the brightest being 1. This method of describing the brightness of a star survives today. Of course, Hipparchus had no telescope, and so could only see stars as dim as 6th magnitude, but today we can see stars with ground-based telescopes down to about 22nd magnitude.

When astronomers began to accurately measure the brightness of stars using instruments, it was found that each magnitude is about 2.5 times brighter than the next greater magnitude. This means a difference in magnitudes of 5 units (from magnitude 1 to magnitude 6, for example) corresponds to a change in brightness of 100 times. With equipment to make more accurate measurements, astronomers were able to assign stars decimal values, like 2.75, rather than rounding off to magnitude 2 or 3. There are stars brighter than magnitude 1. The star Vega (alpha Lyrae) has a visual magnitude of 0. There are a few stars brighter than Vega. Their magnitudes will be negative.

Astronomers usually refer to 'apparent magnitudes', that is, how bright a star appears to us here at Earth. Apparent magnitudes are often written with a lower case 'm' (like 3.24m). The brightness of a star depends not only on how bright it actually is, but also on how far away it is. For example, a street light appears very bright directly underneath it, but not as bright if it's 1/2 a mile away down the road. Therefore, astronomers developed the 'absolute' brightness scale. Absolute magnitude is defined as how bright a star would appear if it were exactly 10 parsecs (about 33 light years) away from Earth. For example, the Sun has an apparent magnitude of -26.7 (because it's very, very close) and an absolute magnitude of +4.8. Absolute magnitudes are often written with a capital (upper case) 'M'.

Image of the spiral galaxy NGC 4414
From Here To There

We all know that our galaxy, the Milky Way, is big -- very big. So big in fact that its size is impossible to grasp. To cope with the astronomical distances of galaxies, since miles or kilometers won' ...
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Sunset over west Maui
The Color of The Sunset

Color in the form of pigment does not exist in the atmosphere. Instead, the color we see in the sky results from the scattering, refraction, and diffraction of sunlight by particles in the atmosphere, ...
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Reading The Colors of the Spectrum

Did you ever wonder how scientists can tell us so much about distant stars, for example, the surface temperature or chemical makeup of a star, light years away from Earth? Scientists can only use what ...
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