Lunarglow – Astronomy & Space

Archive for April, 2010

High power green laser pointers are becoming more and more popular for use in astronomy. Whether you are star-gazing with your astronomy club buddies or conducting an astronomy lecture outdoors, there is nothing more frustrating than unsuccessfully trying to identifying a star or constellation in the sky. Before portable lasers were available, the only ways were to either point to it with your index finger or describe the approximate position verbally. With new technology comes new hope for astronomers worldwide! By using a high power laser pointer, it is now possible to aim a visible laser beam virtually touching the star or constellation you want to point out. The era of astronomy laser pointers is here.

Green Laser Pointers for Astronomy

Green laser pointers are considerably brighter than all other visible color lasers because the human eye is most sensitive to the color green. At the same output power, a green portable laser will appear much brighter than either a yellow, blue or red laser. When we speak of the term “astronomy laser pointer,” it is most often associated with a green laser pointer.

Telescope Alignment with a Laser Pointer

Green laser pointers are not only useful for pointing out stars and constellations, it has other uses in astronomy as well. You can mount a green portable laser onto a telescope using its factory provided brackets (make sure to align the laser parallel to the telescope). If brackets are not available, you can just hold the laser down using your hands. A green laser pointer mounted on a telescope can make aligning the telescope to objects in the sky much faster and easier.

Power Output

Green laser pointers come in a variety of power output ranging from 1mW to 500mW. Which one is suitable for astronomy? More specifically, which is most suitable for your needs? What power output should you choose?

1) A 5mW green laser pointer has a bright laser end “spot”. The actual laser beam is only faintly visible. These are more suitable for presentation purposes and not astronomy.

2) A 15mW – 75mW green laser pointers emit a bright laser beam making them a good choice for astronomy.

3) At 95mW – 150mW, the green beam is even brighter offering extreme brightness, visibility and distance.

4) As you increase in power output, the laser beam will become brighter and more solid in color. The best suggestions if you are looking for an astronomy laser is to purchase something you are comfortable with paying.

5) SKYlasers offers power adjustable lasers where you can adjust the power output between a high-power and low-power setting.

Warning

Do not point any laser pointer devices at any flying aircrafts in the sky; it is a very serious offense in most countries.

I love watching astronomy shows about things like the big bang or black holes on the science and discovery channel. Is there a website where I can watch documentaries like this?

I wanted to know some of the recent discoveries made in astronomy, to see which was is the most interesting to me.

I know he explained gravity but I don’t understand how Newton’s work linked physics and astronomy? Thanks in advance

Astronomy is a serious science. Astronomy for kids is a thought provoking pursuit that can teach them about the sciences in general. Kids are naturally drawn to many aspects of astronomy. These include the moon, the stars and far distant galaxies.

The Earth’s closest neighbor is the moon. It orbits our planet once every 27.3 days. Because it is so close, it is the only space object that a human has ever walked on, other than Earth of course. One of the important benefits of our relationship with the moon is the tides it causes. It’s one of the first objects that can spark a kid’s interest in astronomy because it can be clearly seen with the human eye.

Then there’s our sun. The gap between our home and the sun is very large. We are between 91 and 94 million miles from the sun. The reason for the variance is Earth’s elliptical orbit. Without the sun there would be no life on Earth. The sun provides both light and heat to the planet. Most people don’t realize that the sun accounts for around 98% of all the mass in the solar system. Think about how small a person is compared to that.

Our sun and solar system reside in a galaxy called the Milky Way. It’s full of space stuff. But most of the galaxy is empty nothingness. That’s a lot of nothing because our galaxy is 100,000 light years across and 3,000 light years deep. We’re somewhere in the neighborhood of 30,000 light years from galactic central core. Even with all that space there are about 100 billion stars in the Milky Way. The galaxy’s name comes from the many stars near the center. From Earth it looks like a Milky Way, a large pool of milk. There are four types of galaxies – elliptical, lenticular, irregular and like the Milky Way, spiral.

You can find a wealth of resources for astronomy for kids on the internet. In fact there are many star charts, charting programs, images, videos, and other resources .

i`m only 16 but i am thinking about going into astronomy but i don’t have a clue what you have to do for it! it would be really helpful if you could mention uni courses to get into it? and how hard is it? any suggestions about NASA?

Black holes are probably the most fascinating (theoretical) objects in astronomy. Such objects, which scientists believe must exist, would account for the spin-rate of our galaxy, which cannot be explained by the combined mass of the visible stars. But exactly what are black holes?

A paper, “Philosophical Transactions of the Royal Society in London,” written as early as 1783 by John Michell, a Cambridge don, pointed out how a star which was massive and compact enough could have such a strong gravitational force that light could not escape it. It took Einstein’s general theory of relativity in the 20th century and the work of an Indian graduate student, Subrahmanyan Chandrasekhar, in 1928, to work out the mathematical details of how massive a star would have to be to spawn a black hole.

A black hole is believed to begin with a star. The sun, with a diameter of about 865,400 miles, is considered an average sized star, and is basically a huge thermonuclear “reactor” which has enough “fuel” to keep it burning for many, many generations. But what happens when a star’s fuel burns out?

There are various scenarios, depending on the size of the star. A cold (burned out) star about one and a half times the size of the sun (which is now known as the Chandrasekhar limit) will collapse under its own weight. A live star even many times the size of the sun does not collapse because of the outward force generated by its powerful nuclear explosions. When this nuclear force is gone, however, such massive bodies undergo dramatic changes.

A star less massive than the Chandrasekhar limit still has the ability to stop contracting at about a radius of just a few thousand miles. In such a state it is called a “white dwarf,” and one cubic inch of its mass weighs hundreds of tons.

Another scenario for a cold star about one or two times the mass of our sun is to contract into a “neutron star.” A neutron star can have a radius of roughly ten miles and weigh as much as hundreds of millions of tons per cubic inch.

Since gravitational pull increases in proportion to mass, when stars collapse, their surface gravity become stronger the more compact they become. That’s because with a neutron star, for example, you may have a body with a ten-mile radius exerting a gravitation pull equivalent to a star several times the size of the sun. And that’s massive (in the colloquial sense)!

But as spectacular as such transformations seem, they are nothing compared to the collapse of a star many times the size of the sun. In such a case, the collapse is not halted at a radius of thousands or even ten miles. The force of its massive weight ensures its continued collapse until it reaches a point, according to general relativity, where it has infinite density and space-time curvature. Its radius is a fraction of that of a neutron star. And, thus, a “black hole” comes into being.

A black hole has such a strong gravitational force that nothing, not even light, can escape its pull. This renders a black hole virtually “invisible” — if you shined the most powerful light at such a body, you couldn’t see it because the light would get trapped in the black hole and never reflect back to reach your eyes. Furthermore, inside a black hole, the laws of nature as we know them would break down completely, leaving no viable method of predicting any future events within the black hole.

But if we can’t see black holes, how do we know they exist? Although direct proof of their existence still alludes us, we have evidence which seem to support (not prove) their existence. We have cases of a star revolving around an invisible object, sometimes assumed to be a black hole. Occasionally we see spectacular “fireworks” in remote regions of space, which sometimes is assumed to be produced by matter spiraling into a black hole, creating powerful energy surges. (The reason this energy is capable of reaching us is because it has not yet entered the black hole’s “event horizon,” the point of no return, from where nothing can escape.)

So far, all of the above, even if not fully proven, are based on mathematical calculations, logical deductions and observations. However, some fanciful speculations that go beyond the basics, seem to border on the bizarre. One theory suggests that going through a black hole, if it were physically possible, might be like going through a “worm hole” in space. That is, you might come out in a completely different part of space.

As you can see, scientists sometimes go beyond the verifiable, and venture into the unknown and even into the downright bizarre. What I find even more bizarre is how some of the same scientists will not even venture into the concept of God, despite the fact that there is more than ample logical evidence to suggest that an intelligent creator must exit. Why? Because we can’t “prove” God’s existence? Like, we can really prove everything else that’s accepted as science.

by Josh Greenberger
from shopndrop.com

live.pirillo.com – It may not be as cool as going outside and using your telescope to view the night sky, but Stellarium allows you to view the night sky (and more) from the comfort of your computer screen!

Teaching astronomy or other space sciences? Developing a Web portal or teaching materials for a course? Space Icons http://www.777icons.com/libs/space-icons.htm will make your portal or printed matters look modern and professional right away. Designed to enhance educational portals, student projects and Web sites, as well as software and printed brochures and handouts, Space Icons look strict and formal wherever they are used.

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