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Bringing the Universe to Your Classroom!


Friday, March 23, 2018

How Newton’s Telescope Changed the World

Sir Isaac Newton didn't use his telescope to find any new things in the universe but he did use it to radically transform how we view the world we live in and the universe as a whole.

Sir Isaac Newton is often considered as the greatest Astronomer and Mathematician to ever live. There is a lot of validity to this claim. This article looks at his famous reflector telescope and describes some of his discoveries.

A reflector telescope is one that uses a mirror rather than lenses to bend light and magnify images. Reflector telescopes, because they are easier to make and can be made in sizes much larger than refractors, are an invention that changed astronomy and our understanding of the universe. The largest refractor telescope in the world is forty inches in diameter and reflector telescopes dwarf this in comparison. There are currently several reflector type scopes that are over four hundred inches in diameter.

Sir Isaac Newton surrounded by symbols of some of his greatest findings. Illustration by Jean-Leon Huens, National Geographic Stock
Sir Isaac Newton surrounded by symbols of some of his greatest findings. 
Illustration by Jean-Leon Huens, National Geographic Stock

Why a reflector is better than a refractor

If you are familiar with a prism or a rainbow you can understand why reflectors are superior to refractors. When light passes through glass the different bands (or colors) pass through at different angles and this causes aberrations or problems in the images. This is called chromatic aberration and it gives us distorted views of what we see through a lens. In the time of Newton glass making and lens making was very primitive and the problems of chromatic aberration were not yet overcome. Today we can make lenses that have almost no chromatic aberration but we can’t make them very large. When a lens gets to be really large it gets very heavy and its own weight will distort the lens and ruin the image.

Newton’s telescope solved these problems. A mirror doesn’t pass light through it. It simply bounces all the light off the surface. There is no chromatic aberration at all. And because you only need to bounce light off the surface you can place the whole mirror on a supporting structure or base which takes a lot of the weight off the mirror. This way you can build much larger mirrors without any distortion.

It is commonly thought that Newton invented the first reflector telescope but it isn’t true. Credit for making the first reflector goes to and Italian Monk, Physicist, and Astronomer named Niccolo Zucchi. He published a book on Optics in the 1650’s and it is this book that inspired Sir Isaac Newton to build his own telescope. Zucchi created his first reflector around 1616 while Newton completed his first (and famous) telescope in 1670. But while Zucchi did make some new discoveries with his telescope it didn’t work well and was difficult to make and to use. It was Newton’s telescope that worked really well and that brought the art and science of reflectors into the world of science.

The real genius of Newton’s Telescope

All of that stuff is remarkable but there is something much more important in Newton’s Astronomy and in his telescope. He didn’t after all, discover moons around Jupiter like Galileo did, or plot the return of a comet like Halley did. But what he did do was tie in Mathematics, Astronomy, and our understanding of the universe using his telescope and his theory of universal gravitation. He proved mathematically that gravitation was a two way operation and that while the earth pulled on a falling apple so the apple too pulled on the earth. This was clearly seen, calculated Psychology Articles, and confirmed in the motions of heavenly bodies which was refined and made possible by the new science of reflector telescopes which we can credit to Newton.

Sir Isaac and his telescope carried on with the work of Copernicus and Galileo by furthering our understanding of the universe we live in and helping us to realize there are laws that govern the whole of the universe. And this rule holds true for falling apples and for planets revolving around stars.

Sir Isaac Newton's Original Reflector Telescope. Image by The Royal Society of London.
Sir Isaac Newton's Original Reflector Telescope. Image by The Royal Society of London.

The actual telescope that Newton built still survives today and is in the care of the Royal Society of London. They keep it on display in London and sometimes it travels the world as part of an exhibit.

Will Kaliff

Source: Free Articles from ArticlesFactory.com
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Thursday, March 22, 2018

Explore the Night Sky without a Telescope

You don’t need a telescope to see a lot of wonderful things in the night sky. For example five of the planets are often readily visible with the naked eye. There are lots of amazing things you can see and this guide will help you find them.

To maximize what you can see in the night sky there are a few things you should do as preparation. Of course the first thing you need is a clear and cloudless night. And this includes the moon. You should try to do your observing on a night with no moon; or at the least the smallest sliver of moon possible. Its brightness will wash out many of the dimmest and most dramatic objects in the sky. Second you should consider your comfort. Make sure you dress appropriately for the weather and bring extra layers of clothing if you are observing during cold months. The temperature late in the evening can be substantially lower than it is during the day and because observing the sky means not moving around much you will be even colder. Bring along any items to help your comfort like a lawn chair or a reclining lawn chair so you can look up without craning your neck.

Stargazing and Meteor Shower Observing - Image by NASA
Stargazing and Meteor Shower Observing - Image by NASA

Find yourself a spot to observe from that is as dark as possible. This means get away from street lights, city lights, house lights, or any other type of light source. Ideally you should drive away from any city that is nearby. If this is not possible then try to find the darkest spot you can. Man-made Light sources have an effect on the night sky by washing out the dimmer objects and they have an effect on your eyes by causing your pupils to close. This will decrease your ability to see the dimmer objects.

Beginning your observing is the most critical time for one big reason and this is why a lot of people don’t realize how rich the night sky really is. It takes your eyes up to a half an hour to fully adjust to the darkness outside. If you go outside and immediately begin looking for object in the sky you may be disappointed but this is because your eyes haven’t adjusted yet! Give it some time and let your eyes fully adjust and you will be amazed at how many more things you see in just a half hour time.

Equipment and stuff to bring along

Get some star maps, planet charts, and reference materials and bring them right outside with you. They will help you to find various objects. But it will be dark outside so you won’t be able to read them! And if you turn on some kind of a light or flashlight your night vision will be ruined. But there is a way to read your charts and materials without ruining your night vision. Cover your flashlight with some type of red cellophane or tape so it only gives off a dim red glow. The reduction in light will have less of an effect on your viewing and your eyes are very insensitive to red light so your pupils will not dilate. You can buy flashlights with red covers online, at astronomy and optical shops, or even at military surplus stores.

Star Maps

Suggested Materials List:
  •  Lawn Chair or Reclining Chair 
  •  Constellation Chart 
  •  Planetary Chart 
  •  Lunar Chart 
  •  Plenty of Warm clothing 
  •  Flashlight covered with red cellophane
  •  Snacks and hot beverages

Things to See

The first place you can start with is the moon (If it is out). And the best viewing will be when it is only a think crescent. This is because when it is like this the sun is casting light on it at a very sharp angle and the surface features will cast long shadows which makes them easier to see. With a full or near full moon the light hits the surface of the moon directly and casts no shadows.

The Milky Way Galaxy – Our solar system is part of a tremendous spiral galaxy called the Milky Way galaxy. You can see this galaxy as a band of diffuse light that stretches across the sky. It takes dark skies and well adjusted night vision to see it but it is quite a remarkable sight. Every star and constellation map will show you where the milky way stretches across the sky.

The Constellations – Finding and identifying various constellations can be a lot of fun. Each constellation represents an object, animal, or historic figure; and learning the story behind them can also be a lot of fun. Identifying constellations is also the only way to go deeper and find other objects like planets and comets. They form the background that everything moves within and they give you a frame of reference for finding these objects. Identifying constellations should be part of every star gazing event you undertake.

The Planets – The planets move around in the sky quite a bit and sometimes they are too close to the position of the sun which means they are not visible at night but five of the planets, when in the right position are easily visible with the naked eye. These are Mercury, Venus, Mars, Jupiter and Saturn. And often times these planets are the brightest objects in the sky. Refer to you planet charts to find current locations of them. One rule of thumb for figuring out whether something is a star or a planet is whether or not it twinkles. Stars twinkle and planets do not. So if you locate an object that you believe is a planet you can watch it for several minutes to see if it twinkles like other stars. If it does not then chances are good you have found a planet.

Colorful Stars – Stars are not all white. This is a common misunderstanding that people have. Stars come in a wide variety of brilliant colors and some of the more notable ones are the bright red Betelgeuse in Orion, the bright light-blue Rigel in Orion, the yellowish-white Altair in Aquila, and the bright red Antares in Scorpio. Finding and identifying these colorful stars can be a lot of fun. It can also be quite easy because some of the brightest stars in the sky are also very colorful from white to blue and red.

Some Objects of Particular Note

There are two very unique objects that are very easily seen with the naked eye on a dark night in the northern hemisphere. These are the Andromeda galaxy and the Hercules Nebula. They appear as tiny wisps of white smoke that look like small cotton balls. Once you start getting familiar with the constellations you should look for these two objects. The Andromeda galaxy is in the constellation Andromeda and the Hercules nebula is in the constellation Hercules.

Periodic and Occasional Objects

The night sky is filled with a lot of objects that come and go in different patterns. Some of them, like meteor showers, occur at around the same time every year. This is when the Earth passes through clouds of space debris. You can check a chart of meteor showers and plan an evening or several evening of watching them. Some meteor showers can give as many as 120 falling stars every hour.

Comets – These can be difficult to view because they are often very dim. But occasionally a comet will become very bright and be easily visible with the naked eye.

The night sky is more than just the moon and the stars. It is a extraordinarily rich environment with objects of all kinds. And given a little bit of time and dark skies you will discover and explore many of the beautiful secrets that it holds; and you can do it without a telescope. All you need is dark skies, a few charts, and a little bit of time.

Will Kalif

Source: Free Articles from ArticlesFactory.com
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Thursday, March 15, 2018

The Drake Equation

American astronomer and exobiologist, Frank Drake, proposed a simple (if, rather lengthy) algebraic equation, back in the early 1960’s - for determining the potential number of communicating civilizations/societies/populations, in our Milky Way galaxy as represented by the variable, N. These would be civilizations that are both, capable of, and are communicating, at some wavelength via the Electromagnetic Spectrum (EMS). These parameters might be applied to any spiral, or barred-spiral galaxy in the universe, comparable in size and age to the Milky Way.

N = R* x Fp x Ne x Fl x Fi x Fc x L Graphic by Dale Alan Bryant
N = R* x Fp x Ne x Fl x Fi x Fc x L Graphic by Dale Alan Bryant

Radio Astronomy is an area of research which uses,  giant, dish radio-telescopes for monitoring the sky for potential EMS signals from extraterrestrial civilizations/societies/populations, emanating from planets in orbit around stars, other than the Sun. The SETI (Search for Extraterrestrial Intelligence) Institute is the largest organization devoted exclusively to this area of research. The EMS, is the natural source of radio, television, visible-light, infrared, ultraviolet, x-ray, gamma ray, cosmic, and other radiations, which continuously surround us, and in fact, pervade the entire Cosmos. It is presumed that any intelligent beings that have reached a certain technological level of existence, will have discovered the potential for the EMS to be used in long-distance communication, particularly, interplanetary and interstellar communications.

Here is the equation, in its entirety:

N = R* × fp × ne × fl × fi × fc × L

Where: N = the Number of galactic civilizations releasing detectable Electromagnetic Spectrum (EMS) signals into space. R* = the average annual Rate of solar-type star formation in the Milky Way galaxy. fp = the fraction of those stars, that form planets. ne = the average number of those planets, that lie in the star's ecological, or, habitable zone. fl = the fraction of those planets, that actually go on to develop life, at some point. fi = the fraction of those, life-bearing planets, that go on to develop intelligent life. fc = the fraction of those planets, that harbor intelligent civilizations/societies/populations, that are capable of developing a technology which releases detectable signs of its existence, through EMS emissions into space. L = the length of time, for which, a given civilization/society/population releases detectable EMS signals into space (the species, Longevity).

In 1961, when the Drake Equation was introduced, it was thought that very few stars harbored planetary systems, and the conservative value of N, generally, was placed at around 36 million. But as of January 2017, it is known that - almost all stars - have at least one, orbiting exoplanet. (Planets orbiting stars other than the Sun are called, 'exoplanets') As many as 8 exoplanets have been detected orbiting one star - and, one planet - orbiting as many as four stars! More than 4,500 confirmed exoplanets are known, to date. Most of these planets lie within one tiny sector of the sky; the only sector analyzed by the Kepler Orbiting Space Telescope, during the first phase of its mission: an area about the size of a postage stamp held at arm’s length! It lies just east of the constellation Cygnus, the swan (also known as the Northern Cross).

The number of new exoplanets being discovered through data which is still being reviewed from Kepler - is rising dramatically - and, so is our expectation for life elsewhere in our universe. Moreover - if algebraic equations are just not your cup of tea - I think you will find that, this one, just might be! - the only variables in the equation that are currently known, are, R*, and fp, so, you can modify the values of the other variables and play around with the equation, conservatively or radically, as I have, to your heart's content! I've obtained values for N, from, in the millions - all the way down to...3.

Here is a guide for plugging in quantities into the variables in the Drake Equation. I say, "guide", but only roughly: some of the variables are confirmed; some of them are assumed - and, still others are entirely unknown, so, as we progress down the line we become more and more unsure of their exact values. But this is where you come in! - YOU get to decide: the number of planets, where life, or even intelligence, has evolved, or, how many planets might lie in a sun's Habitable Zone - and so on.

I've given you some figures - that I input - the last time I played with the equation, but the numbers can vary wildly, depending on your level of conservativeness, radicalism, or liberality, at any given time (please remember, we are using multiplication throughout).

The values of the first two variables are given with some surety: R* (annual rate (whole number, in 'billions') of star formation in Milky Way galaxy) = 400 billion (400,000,000,000). Fp (fraction of those stars, that form planets) = .99 Ne (average number of those planets, that lie in a star's ecological zone) = 2

And now, the fun part (your input - see, I told you!): Fl (fraction of those planets, that actually develop some form of life) =. 01 Fi (fraction of those life-bearing planets, that go on to develop intelligent life) = .05 Fc (fraction of those planets bearing intelligent life, whose populations advance to form civilizations which are capable of communication, via the Electromagnetic Spectrum (e.g., radio, visible-light, etc. ) L (longevity, in years, of such civilization) = 800

My answer here, for the value of N - using extreme conservatism, throughout - was, of course - 95.04. That is: 95 communicating civilizations, within the Milky Way galaxy, alone. That is a rather poor number, comparatively, but it is a bit more than just, "something". In other, less pessimistic moods, I've come up with hundreds of thousands of living civilizations in our galaxy (including ourselves). Give it a try!...

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