The Consequences of the Interaction of Light and Gravity

Posted on February 16, 2016 by 2016spaceodyssey

It is astonishing the extent that gravity and light interact with one another.  This is of course very fortunate for us humans when trying to understand the basic force that is known as gravity.  After Isaac Newton proposed his Law of Universal Gravitation in 1687 is was generally thought that gravity was understood even though there were a few holes in the theory, like Mercury’s strange orbit around the Sun.  It wasn’t until 1916 when Einstein released his paper on General Relativity that Newton’s model was under serious attack.  General Relativity is basically that around objects with large mass, both space and time (spacetime) are warped by the gravity of the objects.  So light can bend around large objects and time will move slower.  The theory was first tested in 1919 by taking pictures of a total solar eclipse and measuring the position of the stars nearby.  But the theory also predicted the existence of “redshift” and “blueshift” of light as an object moves toward or away from Earth.  This phenomenon allows scientists to approximate the relative velocity of distant objects based on the relative shifting of the light.  It was also used by Edwin Hubble to conclude the universe was expanding at an exponential rate due to the extreme redshift of distant galaxies.

The model of General Relativity has withstood countless tests including the most recent discovery of gravitational waves.  It has been used to predict the existence of black holes.  It is used by GPS satellites to correct their clocks due to the difference in time far from the Earth’s surface.  If light and gravity did not interact who can say if humans would have ever come up with a model as accurate as General Relativity.

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The gravity of a large object shifts the frequency of observed light. An example of light interacting with gravity. Wikipedia

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Stonehenge

Posted on February 16, 2016 by Chloe

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Stonehenge. Photographer: Howard Ignatius. 

Stonehenge of southern England is one of the most famous Neolithic structures and burial grounds in the world. Construction on Stonehenge started in 5,000 BCE and continued for 1,500 years.  Its eerily arranged stones, transported from up to two hundred miles away from the site, are an iconic draw for the nearly one million visitors that this site draws every year. Its purpose and significance to those who built it, however, has long been a mystery. As early as the 1960s it was suggested that Stonehenge was an example of archaeoastronomy – perhaps it functioned as an astronomical calendar. While this idea has since fallen out of favor, it remains possible that Stonehenge has a connection to the winter and summer solstices.

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Diagram showing summer solstice alignment. 

The Heel Stone, one of the markers outside of the main circle at Stonehenge, aligns with the center of one of the primary arches. During the summer solstice, the sun rises very close to the Heel Stone but not directly over it. However, it is still off by several degrees, and even accounting for procession it was never aligned. Hypotheses regarding a connection between the Heel Stone and the summer solstice, however, were resurrected when it was discovered that the Heel Stone actually had a twin stone that is now missing. On the summer solstice thousands of years ago, these two stones would have framed the rising sun.

 

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The sun rising on the summer solstice. This photo is misleading; the sun does not rise exactly over the Heel Stone, seen center, though it is very close. 

Stonehenge’s original intended purpose is unknown, but these connections to archaeoastronomy continue to inflame popular and academic imaginations. To this day, thousands of tourists, including many neopagans who assign spiritual significance to Stonehenge, make a pilgrimage to this site for both the summer and winter solstices.

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A reveler at Stonehenge during the 2015 summer solstice. 

Featured image.


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Space Vacation?

Posted on February 16, 2016 by segalastronomyblog

Forget about Florida. Have you ever considered vacationing in space? Thanks to Virgin Galactic, we are getting closer and closer to this possibility. Last year, Virgin Galactic SpaceShipTwo crashed in the southwest desert, killing a pilot and completely destroying the aircraft. However, Virgin is getting ready to launch a second SpaceShipTwo this month in Mojave, California for its’ first test flight.

Known for his radical ideas and sense of adventure, Sir Richard Branson launched the Virgin Galactic project in 2004, with the sole hopes of making space travel available to the public. The concept is for passengers to be carried by another aircraft until they reach 50,000 feet, when the two aircrafts will disconnect and the SpaceShip will continue its’ journey up. Passengers will be able to experience zero gravity.

Some hopeful passengers have already put down $250,000 to reserve a spot on Virgin Galactic when it actually comes out, which could be several years. After going through extensive testing, the aircraft must be certified and licensed by the FAA, which is not an easy task in this field. There are several other companies trying to send people to space, including Jeff Bezos’ Blue Origin. It will be exciting to see this actually happen in the near future!

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Learn more about Virgin Galactic


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Tides+Moon…Relationship?

Posted on February 16, 2016 by segalastronomyblog

If you spend an entire day at the beach, it is pretty obvious to notice that the tide changes throughout the day. Sometimes it comes up all the way to your feet while you lay in your beach chair, while other times the tide can be so low it seems like the water is a mile away from you. Why you ask? The answer is somewhat simple: it has to do with the moon and gravity.

As the moon orbits the Earth, the strength of gravity between the two objects increases and decreases. The force of attraction that the moon has on Earth changes depending where you are on Earth. In places where the force of attraction is strongest, the tides will be highest as the gravity from the moon is literally trying to pull Earth apart. Technically this force of attraction effects all of Earth, but you can only really notice it through tides as the force is not strong enough to move land.

Because of the variance of the force of attraction that the moon has on Earth depending on where you are, the tide fluctuates different amounts around the globe. Factors like latitude, the direction the coastline faces, and the shape of the land around the water all impact the variance of the tides.

Check out these cool pictures of high tide and low tide at the abbey of Mont-Saint-Michel, France

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Low Tide

High Tide


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Shout-out to all the Astronomy Ladies

Posted on February 16, 2016 by Alex Pratte

In a lot of professions today it seems like the ladies are under appreciated, so for my fourth blog I thought it would be nice to give some credit to a couple of smart lady astronomers that paved the way for women in the sciences. As I learned in a really cool BBC article that can be found here, two of those women are Fiametta Wilson and Grace Cook. During WWI, while all the guys where off shooting each other, these two women were observing shooting stars and making sure all the records on meteors were kept up to date. These two were among the first four women to be awarded fellowship of The Royal Astronomical Society which was a huge milestone for women and science (way to go). According to a Dr. Mandy Baily, “in the years between 1910 and 1920 Wilson observed somewhere in the region of 10,000 meteors and accurately calculated the paths of about 650 of them – no small achievement!”(BBC). She also did all of this while bombs were being dropped everywhere and on one occasion had a bunch of falling shrapnel almost hit her (but she still finished her research).

This just goes to show that women are just as capable as men when it comes to observing and calculating the path of meteors. Take that misogynists. Also important to note that the picture below is not just a bunch of random women in front of books. These are the leading women in UK astronomy today.

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Using the Stars to Navigate

Posted on February 16, 2016 by Alex Pratte

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For my third blog, I came across a mental floss article giving some helpful tips on how to navigate at night by looking at the stars. As we all know people have been using the stars to navigate from place to place for really long time, so it seems like something pretty handy to know. Here are a couple of the tips noted in the article:

  • If your trying to find the North Star what you need to look out for are Cassiopeia and the Big Dipper. Once you find the big dipper, what you want to do is “look at the Dipper’s ladle and pretend you’re pouring soup from it. The flow of the space soup will point you straight to the North Star” (Mentalfloss).
  • Below the equator the North Star is not visible, so if you find yourself in Australia or something you’re going to want to find the constellation Crux. Crux is supposed to look like a kite and the trick is “if you draw a line from the top of the kite to the bottom, it will point you south” (Mentalfloss).

So there you go. If you want to read about some more cool tips on celestial navigation you can find the link here

Link to Picture here

 

 

 

 

 

 


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Voyager 2 & Planetary Assists

Posted on February 16, 2016 by mattsastronomyblog

When an object is trying to leave a planet, it must reach escape velocity.  The escape velocity is the speed at which the kinetic energy of the moving body is equal to its gravitational potential energy.  The escape velocity from earth is about 25,000 mph.  So when the Voyager 2 left earth, it had to reach this escape velocity in order to overcome earth’s gravitational pull.  While one might think that once it has left earth, the Voyager 2 must only avoid other planets and it could travel as far as it wanted.  However, this is not the case.  While the spacecraft may have reached escape velocity for the earth, it now has to reach the escape velocity so that it can leave the solar system.  Because of the massive weight of our sun, this is no easy task.  The way that this escape velocity was achieved was using planetary assists.

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The Voyager 2’s Speed Along Its Journey

The Voyager 2 used the gravity of four other planets to achieve this velocity. It passed just close enough so that it could “slingshot” around them and gain speed.  It is absolutely remarkable that these calculations were done in the 70’s when one considers the lack of powerful computers that we have today.


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Where is Everybody?

Posted on February 15, 2016 by astr2110geoffren
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We are Just Ants 

The Fermi Paradox questions how is it possible that if there are so many planets orbiting so many stars existing in so many solar systems making up so many galaxies composing so many superclusters creating our observable universe, how is it possible that we haven’t seen any other signs of intelligent life?

This has many possible explanations, mostly due to the fact that we know so little, thus even the most absurd explanations can be entertained since no one can prove them wrong (not really sciency but whatever). My favorite is that no one has contacted us because there’s a super predatorial apex alien race that goes around killing everybody and we’re the only species unaware of this serial killer race. Everyone except for us is just happy to live in their own little solar system, not sending out electromagnetic signals like we’re doing which could potentially tell this race where we are.

Another really wacky one comes from a short story that tells the conversation between two alien friends. To summarize, they’ve basically discovered our existence and are wondering whether they want to contact us. Usually they would, but the one caveat is that we’re made out of “meat”. And these guys are just completely repulsed by the very thought of us being made out of meat instead of plasma or whatever they’re made out of so they decide to just leave us alone. In fact, they’re actually required to contact all sentient life they find, but we’re so repulsive that they decided to erase all records involving our existence and fly away.

A really mind-blowing explanation is that our perception of the universe is just completely wrong. All our senses, everything we know, is just incompatible with all the other sentient life. We can’t physically observe other life because we just can’t. Our senses and technology aren’t able to see them. We need other senses, but we just can’t. That’s the best explanation I can think of. We just can’t.

There are more plausible explanations out there too. These range from the Great Filter explanation, to the fact that we’re just uninteresting and no one wants to contact us. Whatever the explanation, it really is strange. I just hope I live long enough to see this paradox explained.


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The Serial Killer Known as Light

Posted on February 15, 2016 by astr2110geoffren

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Pretty Much a Giant Lightsaber

Gamma Radiation Bursts (GRB) make up the brightest flashes of light from outer space and it isn’t even a contest. If we had the ability to see them we would probably all instantaneously go blind. These flashes of light can last anywhere from a few milliseconds to a few minutes while releasing as much energy as our sun will produce during its entire ten billion year life span.

Usually these things happen far away from us, in dwarf galaxies where there aren’t really any elements heavier than helium. But this just further shows just how stupidly powerful these bursts of energy are. The closest known gamma ray burst came from somewhere over a hundred million light years away and many others came from places billions of light years away. And when these bursts reach us, they still outshine literally every single other source of light in or outside of our galaxy.

It is definitely a good thing that GRB’s usually only happen so far away from us. If something that powerful were to happen close to us, we would all die very fast. Some scientists have even blamed GRB’s for the Ordovician-Silurian mass extinction that wiped out 85% of the Earth’s species. It is likely that a GRB has directly hit our planet sometime in its lifetime and if it did it would destroy a good portion of the ozone. This would affect species that lived in shallower areas of the ocean more than deeper dwelling creatures. The scary thing is, that geological evidence says that species living near the surface of the ocean were hit harder by whatever caused the Ordovician-Silurian mass extinction. And even though it’s generally known that an ice age helped kill everything off, GRB’s can cause ice ages too. They can convert nitrogen and oxygen molecules into nitrogen dioxide which, if enough forms, can block out a large amount of sunlight- beginning an ice age.

Honestly, the scariest thought for me is that some people believe that the Fermi paradox can be explained by GRB’s. The Fermi paradox basically ponders why we haven’t already encountered other intelligent life since there’s such a large number of other planets out there. If GRB’s are deadly to all life, known and unknown, then one solution to the Fermi paradox is basically that GRB’s kill everything before they have a chance to spread across the galaxy. So basically, if this is true, it’s just a matter of time before everybody on this planet is instantaneously turned into a KFC meal. :]


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Stonehenge: Change the How!

Posted on February 15, 2016 by astrologankeller

We all know Stonehenge as a Wonder of the World, in which there are multiple sets of 3 massive rocks stacked together. The major question revolving around Stonehenge (to the lay person) is how they got the rocks up there, since the technology of the time would have made this incredibly difficult. While this is a valid question, the more important question should revolve around Stonehenge’s purpose!

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A picture of the alignment of Stonehenge

Stonehenge is an astronomic phenomenon, conveying to us that humans caught onto astronomy much earlier than most people would believe. Stonehenge is aligned with the same direction as the sunrise in the Summer Solstice and the sunset of the Winter Equinox, providing evidence of ancient astronomers. Numerous astronomers and archaeologists have worked together to discover other findings regarding Stonehenge.

Many believe that the lining up of the sun and moon with Stonehenge is merely a coincidence; however, scientist Gerald Hawkins has provided evidence of dozens of alignments, gathering more evidence that those who created this phenomenon were well aware of the movement of the sun, moon, and stars.

I personally think that there are too many pieces of evidence that indicate that whoever made Stonehenge knew what they were doing. That being said, this is still pretty contested. What do you think? Did the ancient astronomers that built this know what they were doing? Or were they just farmers who happened to watch stars and get lucky?


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