Astronomy
esiegel | January 4, 2016"Gravitational and electromagnetic interactions are long-range interactions, meaning they act on objects no matter how far they are separated from each other." -Francois Englert
One of the most spectacular predictions of Einstein's General Relativity was the existence of gravitational lensing, whereby a large foreground mass could act as a lens, magnifying and distorting the background light source behind it. Although this was first observed for quasars, large galaxy clusters act as the most powerful lenses.
Image credit: K. Sharon et al., 2014, via http://arxiv.org/abs/1407.2266.
Which is…
esiegel | January 1, 2016"Gamow was fantastic in his ideas. He was right, he was wrong. More often wrong than right. Always interesting; … and when his idea was not wrong it was not only right, it was new." -Edward Teller
Considering what we know about our Universe today, it's hard to believe that just a century ago, Einstein's General Relativity was very much untested and uncertain, and we hadn't even realized that anything at all lie outside our own Milky Way. But over the past ten decades, ten great discoveries have taken place to give us the Universe we understand today.
Image credit: Adam Block/Mount Lemmon…
esiegel | December 30, 2015"You cannot rob me of free nature's grace,
You cannot shut the windows of the sky
Through which Aurora shows her brightening face." -James Thomson
When the Sun emits a flare or a mass ejection in the direction of Earth, these fast moving particles are when Earth's magnetosphere and atmosphere are of the utmost importance for shielding us. The magnetic field bends these ions harmlessly away from our planet, only funneling a small fraction down into a ring surrounding the poles. The atmosphere absorbs the impact, shielding all living creatures below from this radiation, while simultaneously…
esiegel | December 28, 2015"I know there is strength in the differences between us. I know there is comfort where we overlap." -Ani DiFranco
The observable Universe is a big, big place. Some 46 billion light years in all directions, with hundreds of billions of galaxies inside, it's no wonder that we see stars and galaxies in all directions we've ever looked. What's even more of a surprise, though, is that sometimes galaxies that aren't at all close together look like they are, and overlap.
Image credit: Sloan Digital Sky Survey / William Keel, of NGC 3861.
These optical illusions are caused by the uncommon…
esiegel | December 26, 2015“This whole Santa Claus thing just doesn't make sense. Why all the secrecy? Why all the mystery?
If the guy exists why doesn't he ever show himself and prove it?
And if he doesn't exist what's the meaning of all this?” -Calvin, via Bill Watterson
This is our last comments of the week for 2015, and Starts With A Bang can't wait for the new year! All the great things we've worked so hard for this year promise to bring about an even better one in 2016. But that said, there's still more science for this year! This past week saw the following:
When a photon gets redshifted, where does its energy…
esiegel | December 25, 2015"If the expansion of the space of the universe is uniform in all directions, an observer located in anyone of the galaxies will see all other galaxies running away from him at velocities proportional to their distances from the observer." -George Gamow
When Einstein put forth his space-and-time changing theory of General Relativity, one of the consequences he didn't anticipate -- and, in fact, resisted -- was the fact that a static Universe would be unstable, and that the Universe must be either expanding or contracting. While the theoretical work of many, such as de Sitter, Friedmann and…
esiegel | December 21, 2015"For me, the study of these laws is inseparable from a love of Nature in all its manifestations." - Murray Gell-Mann
When you take a glimpse into the deep Universe, beyond the gas, dust, stars and planets of our own galaxy, you enter the realm of the galaxies. In general, they come in two types: the spirals, with neat, orderly arms, and the ellipticals, with a symmetric, bulging shape. But for everything that exists in the Universe a particular way in general, there are exceptions.
Arp 273, with both galaxies clearly affected by the interaction. Image credit: NASA, ESA and the Hubble…
esiegel | December 14, 2015"Youth is the gift of nature, but age is a work of art." -Stanislaw Jerzy Lec
When stars are born, it normally happens in groups of thousands or more, all at once. They range from just 8% the mass of our Sun, which are dim, red, and long-lived, to dozens or even hundreds of times as massive: the brightest, bluest and shortest-lived stars of all. Because they burn through their fuel the fastest, these most massive stars cease to exist the most quickly.
Image credit: Christopher Tout, Nature 478, 331–332 (2011), via http://www.nature.com/nature/journal/v478/n7369/full/478331a.html.
Yet even…
esiegel | December 13, 2015“The time will come when diligent research over long periods will bring to light things which now lie hidden. A single lifetime, even though entirely devoted to the sky, would not be enough for the investigation of so vast a subject... And so this knowledge will be unfolded only through long successive ages. There will come a time when our descendants will be amazed that we did not know things that are so plain to them... Many discoveries are reserved for ages still to come, when memory of us will have been effaced.” -Seneca
If you love what's out there in the Universe -- the science, the…
esiegel | December 9, 2015“You are the salt of the earth. But remember that salt is useful when in association, but useless in isolation.” -Israelmore Ayivor
When NASA's Dawn spacecraft began photographing Ceres, one big surprise emerged: the presence of a spectacularly and unusually bright spot at the bottom of Occator crater. As we got closer, we discovered it was a series of spots in the lowlands of the crater bed, and that there were other suspicious, smaller bright spots elsewhere on the surface.
Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA, converted from Nature Publishing Group press’s YouTube channel.…
esiegel | December 9, 2015"We cannot be vengeful. We need to find pono [righteous] solutions. We need to find good things for astronomers. Cooperation is, I think, really the true part of our human nature, not competition. I think we have to go back to cooperation to survive the future." -Kealoha Pisciotta, president of Mauna Kea Anaina Hou
If you want to explore the Universe, you need a telescope with good light gathering power, a high-quality camera to make the most out of each photon, and a superior observing location, complete with dark skies, clear nights, and still, high-altitude air. There are only a few places…
esiegel | December 8, 2015"Mars is much closer to the characteristics of Earth. It has a fall, winter, summer and spring. North Pole, South Pole, mountains and lots of ice. No one is going to live on Venus; no one is going to live on Jupiter." -Buzz Aldrin
When we think about life in the Universe, we think about Earth-like conditions: a hospitable atmosphere devoid of poison, flowing water and the right temperatures and pressures for liquid on the surface, and just the right distance from the parent star to make it all happen. But perhaps life exists in abundance under very different conditions: in the atmospheres of…
esiegel | December 7, 2015"It will be found that those contained in one article [class of nebulae], are so closely allied to those in the next, that there is perhaps not so much difference between them, if I may use the comparison, as there would be in an annual description of the human figure, were it given from the birth of a child till he comes to be a man in his prime." -William Herschel
When a star like the Sun nears the end of its life, a few things are inevitable: nuclear fusion in its core will cease, the outer layers will be blown off, and a white dwarf and planetary nebula will be the result. But this…
esiegel | December 6, 2015“Every moment of light and dark is a miracle.” -Walt Whitman
Every once in a while, the Earth hurtles through the orbital path of a comet or asteroid, with the Sun having torn tiny bits of debris from the parent body. As a result, the Earth strikes these dusty fragments at speeds often exceeding a hundred thousand miles-per-hour, resulting in a tremendous light show: meteor showers!
Image credit: NASA / public domain, of the Leonid meteor shower (1997) as seen from space.
Most people wind up disappointed in meteor showers for two reasons: they don't know what to expect and they don't know…
esiegel | December 3, 2015"After 20 years of exploring planets as big as Jupiter around other suns, we still have a lot of questions left open. For instance, we don’t understand what is the physical mechanism that forms Jupiter-like planets with orbital periods as little as a few days." -Alexandre Santerne
By surveying an area of the sky containing over 150,000 stars visible to it, the Kepler satellite monitored each one over a multi-year period looking for periodic changes in brightness. Thousands of planetary candidates emerged via the transit method, where periodic dips of 3% or less were noted with regularity.…
esiegel | November 30, 2015"Lots of science fiction deals with distant times and places. Intrepid prospectors in the Asteroid Belt. Interstellar epics. Galactic empires. Trips to the remote past or future." -Edward M. Lerner
Of all the asteroids we've ever discovered, it's arguably the very first one, Ceres, that's got the most to teach us. Currently being mapped at higher and higher resolution by NASA's Dawn Spacecraft, Ceres isn't just the largest asteroid we've got, it's also one of the least inclined, orbiting the Sun with a tilt of just 3 degrees.
Image credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA, from…
esiegel | November 16, 2015"Truth is more valuable if it takes you a few years to find it." -Jules Renard
Of all the star-forming nebulae in our galaxy, the Trifid Nebula -- Messier 20 -- is thought to be the newest and youngest. Named "Trifid" for its threefold appearance, the blue reflection nebula, the red emission nebula, and the dark, star-forming dust lanes, it also bears a resemblance to the French tricolor flag.
Image credit: flickr user Marc Van Norden, via https://www.flickr.com/photos/mvannorden/8275065973/in/photostream/.
Because of the large number of young, hot stars still inside, the Trifid Nebula is…
esiegel | November 11, 2015"I have worn myself thin trying to find out about this comet, and I know very little now in the matter." -Maria Mitchell
Originating from the Kuiper belt and the Oort cloud, comets are generally thought of as periodic objects, with their initial trajectories having been perturbed by either Neptune, another distant object or a passing star or rogue planet.
Image credit: ESA/Rosetta/NAVCAM.
But most comets aren't periodic; they're transient instead, where a trip into the inner Solar System gives them additional gravitational perturbations, causing them to either fly into the Sun or gain…
esiegel | November 10, 2015"Some kind of celestial event. No — no words. No words to describe it. Poetry! They should have sent a poet. So beautiful. So beautiful... I had no idea." -Dr. Ellie Arroway, Contact
Back in 2006, the International Astronomical Union defined the term "planet" for the first time by three criteria: its ability to orbit the Sun, to pull itself into hydrostatic equilibrium, and to clear its orbit. This not only excluded all exoplanets, but it set up impractical criteria for measuring exoplanet properties.
Image credit: ESO.
But UCLA scientist Jean-Luc Margot found a new planetary test that…
esiegel | November 9, 2015"It is true that we are made of dust. And the world is also made of dust. But the dust has motes rising." -Muhammad Iqbal
If you want to view the Milky Way in all its true splendor, you need to go beyond visible light, as the cosmic dust that gives rise to new stars also absorbs visible light, robbing us of a view of our galaxy. But those other wavelengths that are more transparent to the dust -- infrared and microwave -- are absorbed by Earth's atmosphere. If we want to see what's going on, we've got to go to space.
Image credit: ESA and the Planck Collaboration.
With nine different…