Source: abovetopsecret.com
This photo, based on our current models of the observable universe, shows our cosmos on the grandest scale that we can imagine. Each dot is a cluster of galaxies, rich with stars and (probably) planets. Every law of the universe has teamed up to produce this image: the laws of gravity, astrochemistry, planetary geology, etc. This is the sum of their parts. So what else is out there?
Source: slate.com
This picture is an artist’s depiction of what the rocky planet Kepler-186f might look like. On April 17, 2014 astronomer’s announced that they had found this planet using the transit method, making it the first confirmed earth-size exoplanet in the habitable zone! There is no data yet on whether or not Kepler-186f has an atmosphere or has any water in its atmosphere, but astronomer’s that it is in the right location in its star system to have liquid water.
While much of what is said regarding Kepler-186f at this point is mere speculation, it does tell astronomers that earth-size planets in the habitable zone might not be a rare occurrence. While it is too distant to determine its atmospheric composition with telescopes, we soon may have the capability to get accurate data on it, which could tell us if Kepler-186f has water or not. Whatever the results, knowing that we now have the technology to at least find earth-size planets means that the next several years could greatly change how we foresee the future of astrobiology.
So all the planets know that Saturn’s rings give it a really over-inflated ego. But now there’s good news! Maybe it’ll quit bragging now that it looks like there’s another planet with a bigger ring system. Scientists think they’ve found an extrasolar planet with an elaborate ring system, the first discovery of a planet with rings outside of our solar system. This was announced at the American Astronomical Society in January of 2012.
The image (from the web page of the linked article) is an artist’s representation of what this system might look like. According to the data, the planet orbits its star at about 1.7 AU, but its mass is not yet known. The outermost rings stretch to a diameter of about 120 million kilometers – that’s an astonishing 0.8 AU, compared to Saturn’s major rings that extend for a diameter of about 270,000 kilometers. For comparison, if this system were swapped out for Mars, which actually orbits at a slightly shorter orbital distance of 1.5 AU, the rings would almost be only .1 AU from Earth’s orbit!
This video tells us about the history of Halley’s Comet, which turns out to have actually been documented in medieval history in previous passes by the sun. Because of the rarity with which comets actually appear in our night sky, they used to be tied to ancient superstitions; for example, to the ancient Chinese they signaled a period of rapid change. Now we know that comets are simply chunks of ice and dust formed in the outer regions of the solar nebula. After a gravitational encounter with a jovian planet, a comet may fall into the inner solar system, where it would brilliantly light up our night sky.
Because comets formed in the outer solar system, Kepler’s Third Law tells us that they have very long orbital periods compared to the Earth (those that fall into the inner solar system also have highly elliptical orbits). Thus, when a comet does fall to the inner solar system, it only reappears usually after several decades. Halley’s comet, for example, will not reappear until 2061.
It all boils down to the greenhouse effect! Yes, the greenhouse effect goes beyond causing global warming here on Earth. It is, in fact, necessary for life on Earth; without it, the planet would be far colder than it is today. Certain gases present in both Venus’s and Earth’s atmosphere essentially act like a blanket over the whole planet – temporarily trapping heat, thus slowing energy’s escape in the form of light. Examples of these gases are carbon dioxide and water vapor.
Venus is so hot simply because its atmosphere is dominated by carbon dioxide, while Earth’s atmosphere only has trace amounts of greenhouse gases. The carbon dioxide in its atmosphere bakes the surface to hotter than a pizza oven. But what’s truly scary is that if Earth were moved closer to the sun, the same thing would happen to it. Water vapor from the ocean and the carbon dioxide trapped there would escape into the atmosphere, warming the earth, causing more water vapor and carbon dioxide to escape. This process that causes itself to repeat is an example of a positive feedback loop – and it would cause Earth to take on an image similar to Venus. So next time you see Venus shining brightly as the evening star, take a moment to appreciate the fact that Earth does not resemble an image that can only be enjoyed from a great, great distance.
In only the recent history of astronomy, we’ve began to understand that our solar system is in fact no different than other star systems in the universe. We now understand that stars in fact all form from a collapsing cloud called a nebula, which is composed mostly of hydrogen and helium gas, and trace amounts of other materials like hydrogen compounds, minerals, and metals which make up the asteroids and planets that orbit stars.
What is most intriguing is that we can see that it is a natural consequence of star formation for planets to form in its orbit. Does this mean that all stars have planets in their orbit? How does this affect the odds of another earth-like planet forming in orbit of another star? Astronomers are still pondering these questions, but I think that there may be more earth-like planets out there than we think. What are your thoughts?
Photo Source: Hubble’s Law
Considering the topic of what light can tell us, Hubble’s Law is one topic I’ve always found greatly interesting. As the picture suggests, the redshift of a distant galaxy is in direct linear proportion to its distance from Earth. This is the essence of Hubble’s Law – which relates a galaxy’s radial velocity from us to its distance – this means that we can find out how far something is from us just by looking at it!
Mathematically, it is given by v=Hd (v – radial velocity; H – Hubble’s constant; d – distance). Astronomers can find the speed of a galaxy away from us by its redshift, and then it’s easy to solve for its distance! In fact, Hubble’s Law is what has indicated to physicists that our universe behaves as a uniformly expanding body. Just one of the many things that light can tell us about the universe!
Photo Source: Absorption Spectrum The photo above is the full absorption spectrum of the sun. The black lines come from the different chemical elements within its atmosphere, and this is true for all stars! Different elements absorb and emit light at different wavelengths from one another. Scientists have conducted (here on earth) experiments to determine what wavelengths of light are emitted by the elements. This means that we can determine what elements are present within another star simply by looking at its spectrum! Just one of the many things that light tells us about our universe.
Isaac Newton (December 25, 1642 – March 31, 1727)
When Newton was around 23 years old, the last major epidemic of Bubonic Plague in England took place, known as the “Great Plague of London.” Also, when Newton was a teenager, the Wars of the Three Kingdoms were taking place, with the conflict in Scotland having a notable effect on Britain’s history. These civil wars resulted in Charles II losing rule over the Scots to Oliver Cromwell, the Lord Protector. He would later, however, become King of Great Britain and Ireland when Newton was 18, in April of 1661.
Robert Hooke (July 28, 1635 – March 3, 1703) is famous for his discovery of cells. Using a microscope, he observed the cells of a piece of cork, and sketched his observations. He is also known is physics for Hooke’s Law describing the simple harmonic motion of a spring. Hooke was the first Curator of the British Royal Society. There is also a fairly well documented feud between Hooke and Newton; the two argued over who deserved credit for the law of gravitation, among other things.
What’s most interesting to me about the history of astronomy is how far it stretches across the history of the world (in geography and time). I can’t think of any subject of study (except for history itself) that goes across all time periods and all cultures to the extent that astronomy has.
Night Sky 2 The hyperlink above is to a webpage with the information and a review for a REALLY cool observing app! I got Night Sky 2 before I even took an astronomy class at Vandy, and it’s easily my favorite. You can get real-time views of all constellations, planets, stars, satellites, and even comets! Not going to lie, it definitely saved me a LOT of time out in the cold in the introductory astronomy lab when my planisphere just wasn’t cutting it. Also attached is a photograph of what the app’s display looks like, which comes from the hyperlinked source. You face your phone’s camera in a certain direction, and it shows you what the sky looks like looking that way at that time! 
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