Pink Light

Posted on February 20, 2013 by Elizabeth Merriman

There are many interesting things about light, particularly those wavelengths we cannot see.  Looking at the light coming off of the Earth, we see what looks like a black body curve, but with chunks missing where greenhouse gasses absorb light.  

Some animals are able to see the infrared light that is given off by other animals, in essence, they are able to see heat.  This effect can be replicated with heat sensing cameras, which are used in some security systems and frequent MythBusters episodes.

Sticking to visible light, we have looked at different wavelengths to learn about prisms, the size and temperature of stars, and Doppler shift, but where does pink fit into this picture? There is no pink light.  Pink is not simply unsaturated red, which is why when you mix red and white paint, you just end up with light red, not pink.  Did this bother anyone else in elementary school?  To get pink paint, you had to add a little bit of blue.  This is because pink is how our eyes interpret a lack of green.  If you mix what our eyes interpret as red (that is, paint that scatters red light and absorbs all other wavelengths) with what our eyes interpret as violet (that is, paint that scatters violet, or less of paint that scatters blue, and absorbs all other wavelengths), our brains do not interpret that as two separate colors at once, but rather, pink.  This is the same reason computers and TVs can use only three colors of light to depict the whole spectrum-our eyes interpret these separate wavelengths of blue, green and red light in the same way they interpret a single wavelength of light in the visible spectrum.

I highly encourage people to watch the video, I could not figure out how to embed it.

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Gravity around the Solar System

Posted on February 20, 2013 by Elizabeth Merriman

In class, we looked at why an astronaut experiences weightlessness in the space station, even though the force of gravity is not significantly less than on the surface of the Earth.  This is because the space station is falling at the same speed as the astronaut and traveling so fast that it misses the Earth.  Here is a video that does a good job explaining this.

Why are Astronauts Weightless?

However, what about the rest of the solar system? We spent a lot of time looking at the Earth and the Moon, but what about other planets?

Relative Strength of Gravity throughout the Solar System

It is interesting to see how much stronger the gravitational field around Jupiter is than the other planets, particularly since Saturn is about the same size.  In this picture, the depth of the gravity well corresponds to the amount of energy it would take a to escape the planet and the widths of the planets are to scale with the depths of the wells, but interplanetary space is not to scale.  A few interesting things to notice:  Mercury is so small and close to the sun that it does not create much of a gravity well, and a human could throw a baseball into orbit around Mars’s moons.  I spent a long time staring at this poster, since my roommate had it sophomore year, but I encourage you all to look at it and discover some cool stuff about our solar system.

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The Webb Space Telescope: the Future of Viewing the Past

Posted on February 20, 2013 by zvgio

Every time you look at the stars , you are looking back in time. The universe is a big place and light takes time to move through it, so if you’re currently admiring Polaris, the photons hitting your eyes have been traveling for about 434 years to reach you. That may seem like a long time, but it’s peanuts compared to the 2.5 million years that it takes light to reach us from our closest neighboring galaxy, Andromeda. However, our eyes are small and can only collect so much light and the Earth’s atmosphere is disruptive to telescopes here on Earth, so since 1990, the Hubble Space Telescope has been looking back in time for us, seeing further than our eyes ever could, but to today’s astronomers, it’s just not far enough. This is because the Hubble sees only visible and near-visible wavelengths of light and the oldest light in the universe is infrared. This ancient light wasn’t always infrared, but our universe is constantly expanding and stretching and the light from the formation of the earliest stars galaxies stretched with it to longer, infrared wavelengths. Enter the Webb Space Telescope. Slated to be launched in 2018, the Webb will be seeing in infrared, collecting light from nearly the beginning of space-time. This behemoth has a 6.5 meter mirror as compared to the Hubble’s 2.4 meter primary reflector, so it will have far greater resolving power than any space telescope launched before. Webb is truly a marvel of modern engineering and I for one can’t wait to see what it sees.


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Copernicus vs. Tycho Brahe

Posted on February 20, 2013 by JT McJunkins
While both Copernicus and Tycho contributed to the evolution of astronomy and the Scientific Revolution in general, the nature of their accomplishments and challenges to the status quo were fundamentally different and defined their respective receptions by the scientific community … Continue reading →
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Light

Posted on February 20, 2013 by michaelglindsay

Light

Light

Light, to me, will always carry a sort of mystical quality, regardless of how great our understanding of it grows to someday be. It travels across the cosmos carrying tantalizing hints at what lies beyond our short grasp. It is the information super highway of the Universe, bringing information and description of what else exists across time and space so that we may know just how much there is left to learn in regards to heavenly bodies. I suppose much of it can be chalked up to human ingenuity; the analyzing of spectra to determine chemical composition is not intuitively suggested by light, and the amount of work and creativity put into telescopic and imaging technology should never be taken for granted. This being said, these observations and advancements (among most other things)  would be near inconceivable without the presence of light. In the past century, with Einstein’s theory of relativity and its implications, light has become even more essential to our understanding of the fundamental nature of the Universe. Light is the building block of everything else; life, the creation of mass, the formation of the Universe. Understanding and applying our knowledge of light seems to me to be the most promising and interesting scientific task. How could it not?


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A more “earthbound” use of the Doppler effect

Posted on February 20, 2013 by astrdylan

When I was reading about the Doppler effect in the textbook, I found it easy to visualize the way we use the Doppler effect to understand the movements of astronomical objects, but I didn’t realize that we had other uses for Doppler a little closer to home. After doing a little bit of research, I learned that one of the biggest applications of the Doppler effect is one that we all dread: a policeman’s speed radar gun works thanks to Doppler.

As someone with a propensity to drive a little too fast sometimes, I thought I should do my research. It turns out that radar guns send electromagnetic waves at a moving object (e.g., your car), and when those waves hit the object, they bounce back at the gun, which has a receiver as well as a transmitter. The receiver interprets the wavelength of those reflected waves, and since the Doppler effect tells us that the degree of blueshift that occurs when an object moves toward us is dictated by the speed of that object, a policeman can tell how fast you’re going based on how much shorter the wavelengths bouncing off your car are, versus how short they would be if you were driving the speed limit. So, the next time you get pulled over for speeding and the officer asks if you know how fast you were going, you not only know, but you know how he/she knows, too:)


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Near-Earth Objects: Experiences and Implications

Posted on February 20, 2013 by werdercj

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Meteor trail over Eastern Russia.

On February 15, 2013, two very significant astronomical events occurred unusually close to us; the highly publicized meteor explosion over a Russian city overshadowed the close approach of a much larger asteroid orbiting Earth.  The contrast between these two events is what struck me as most interesting and informative about the current limits of our knowledge of astronomy, particularly within our own solar system.  The Russian meteor blast devastated the city of Chelyabinsk in an enormous blast; scientists estimate that a meteor of this size (about 55 feet wide) only enters the Earth’s atmosphere about once every 100 years.  What was most unsettling about this, however, was that it was completely unexpected; although this meteor was over 50 feet wide and weighed about 10,000 tons, it was much smaller than objects we can currently track in space.  Thus, we had no means of predicting its arrival until it entered the Earth’s atmosphere and plummeted toward Russia with tremendous speed.

Asteroid 2012 DA14 has a very different story.  It was discovered about a year ago, and has since been studied.  On February 15, it passed 27,700 km from the Earth’s surface: extremely close by astronomical standards.  The asteroid is about 150 feet wide and weighs an estimated 130,000 tons, making it far larger and thus detectable given current technology.  This also means that it would pose a far more significant threat were it to enter the Earth’s atmosphere.  However, it posed no threat as it passed Earth because scientists were able to predict its orbit extremely accurately; we knew when it was going to pass Earth, and almost exactly how far away it would be.  The passing of 2012 DA14 was educational rather than threatening; astronomers will be able to observe its speed and orbit before and after passing so close to Earth to learn about the properties of near-Earth asteroids, and how their orbits are affected Earth’s gravitational pull at such close distances.

The divergent outcomes of these two near-Earth objects highlight the importance of furthering our study of our solar system, and the universe as a whole.  As in other practices, failure reveals the current weaknesses and limitations of astronomy.  Success, on the other hand, can be blinding.  Indeed, it is quite amazing that we were able to detect 2012 DA14 a year ago and make accurate predictions regarding its path.  Regardless, it is more important to realize that there are innumerable objects that we have not or cannot yet detect that could pose threats to Earth in the future.


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Astronomy’s Evolving Role in Society

Posted on February 20, 2013 by werdercj

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Above: Stonehenge is an ancient structure in England that was used to mark the seasons.

Archaeoastronomy is the study of ancient structures in search of astronomical connections.  It shows how people in the past understood and utilized phenomena they observed in the sky.  To me, the most interesting part of this is the progression of the practical purposes served by astronomy throughout history.  One early purpose of astronomy was to develop an accurate calendar; this was very beneficial for agriculture, and allowed for regulation of religious activities and dates.  Regardless of the purpose of astronomy in each particular ancient society, much of ancient astronomy was used for practical everyday purposes: calendars, time telling, navigation, and the like.  Technology has rendered many of these uses obsolete in recent times, so much of our study of astronomy is now focused on explaining phenomena of the universe in a quest for a deeper understanding of its inner-workings.

However, there are still very important uses for our newer findings, including tracking objects orbiting dangerously close to Earth, a study that has gained much attention with the rare asteroid and meteor events of the past week.  The research of today seems to focus more on similar rare events, as well as on further investigation outside of Earth by sending people and equipment into space.  Although much of this serves to satisfy our inherent curiosity, there is no telling what purposes new findings could serve in the future.  After all, ancient cultures had to make observations of the sky before they could analyze them and find practical uses for their findings.  This process continues today, just in a far more sophisticated manner.  By nature, scientific inquiry begins with observations; if we continue to make new or more detailed observations as technology develops, we will consequently have more questions about the universe that need answering.


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Plato’s Cosmology

Posted on February 20, 2013 by JT McJunkins
While Plato’s cosmology may seem odd to a modern observer, it was a carefully reasoned, innovative theory in its time. Plato departed from his predecessor’s ideas beginning with his belief in a deity. While pre-Socratic philosophers attributed order in the … Continue reading →
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The OWL

Posted on February 20, 2013 by marknshirleyvu

While reading about different types of telescopes here on Earth I stumbled across a cancelled project known as the OWL (Overwhelmingly Large) Telescope, and overwhelming might be an understatement.  This telescope, a concept developed by the European Southern Observatory, would boast a single aperture measuring 100 meters in diameter, longer than a football field!

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ESO

It is hard to imagine the type and quality of images we would be capable of gathering with a tool of this magnitude.  It would be capable of viewing objects in space with an angular resolution “40 times greater than the Hubble Space Telescope.”  Unfortunately, this behemoth of a project has been postponed due to immense cost (≈ €1.5 billion) and the logistics problems inherent to a project of this size.


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