MILKY WAY

THE MILKY WAY

To earler civilizations, the Milky Way was such a large part of the nightime experience that it was considered by many to be the "pathway to heaven". To our culture, if it is known at all, it is only to the educated because they read about it or the lucky traveler who visits places that do not suffer from the pervasive light pollution that makes it totally invisible anywhere near metropolitan areas.

It is my opinion that anyone who has not seen the Milky Way in all its splendor has not lived a complete life. Seeing this awsome band of glitter, passing from the Southern horizon, almost to the Northern should be a vacation destination on everyone's list.

The Milky Way is a giant spiral galaxy like many others we have discussed on these pages. Like viewing a forest when amongst the trees, we can only imagine what the whole galaxy looks like and this imaginary image of a typical spiral is as good as any.

The Sun is just one of about 200 billion stars that make up our galaxy and it orbits the center about every 200 millions years. That would be one "cosmic year" which provides a great way to seem young again. The Sun is in one of the spiral arms about midway between the center and the edge of the galaxy.

When we see the Milky Way in the sky, it is because we are looking toward the center where vast numbers of stars are in our line of sight. When we look elsewhere, all we see are the stars randomly scattered above and below the plane of the galaxy.

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Southern Milky Way

A good place to start exploring the Milky Way is on the Southern horizon in mid-Summer. The brightest and most interesting part is in and around the constellation Sagittarius. Although this group of stars is supposed to represent the Archer, most people find the "Teapot" easier to identify.

The spout of the Teapot points to the actual center or hub of the galaxy which I have marked with an "X". It happens to be blocked by trees in this photo as I have a limited view of the Southern Horizon and can only photograph small sections as they pass through the notch in the trees.

There are many interesting objects in this photo alone that we will expand upon in future weeks and we will add more large scale views as we move across the Milky Way.

This aswome sight is at it's peak right now and if you can find any way to get out to a dark place to see it, you will never forget it.

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The Lagoon Nebula

This week we highlight one of the most interesting objects in the Southern Milky way, the star cluster and nebula known as the Lagoon Nebula.

It's catalog designation M8 points to its location in the photo of last week.

The first thing to note about the "Lagoon" Nebula is that the person who named it seemed to have a confused idea of what a lagoon is. The dark band through the middle more closely resembles a channel, whereas a logoon is a small body of water surrounded by a ring of coral.

The most conspicuous feature of this nebula in photos is the vast cloud of hydrogen gas illuminated by the hot stars within.

Less conspicuous but even more interesting are the roundish black "globules" that are thought to be stars in the making. These are vast clouds of dust and gas several times larger than the Solar System that are contracting into "proto-stars".

This film and the eye happen to be less sensitive to red light and the brightest part of the nebula is where the hottest stars are. The diameter of the entire group is about 100 light years and is at a distance of about 5000 light years from the Sun.

Just a bit north of the Lagoon is an object known as the Trifid Nebula. It's catalog designation M20 points to its location in our Southern Milky Way photo.

This is another one of those objects that has always seemed to me to be mis-named. To compound the injury, it is even described as "having three lobes, hence the name". I leave it to the reader to judge.

The most interesting feature of this nebula is one that a visual observer or black and white photographer could never have a clue.

The red and overexposed white portions are regions called emission nebulae. They are illuminated by one very hot star that ionizes the surrounding hydrogen gas with ultraviolet emission, in exactly the same way a flourescent light works.

The blue region simply reflects visible light impinging on it directly, like a mirror and is called a reflection nebula. The whole nebula is aproximately 2200 light years from Earth.

This cluster contains about 70,000 stars and lies at a distance of about 10,000 light years.

It is aproximately 50 light years in diameter.

It is an easy target in binoculars on a dark night.

It's catalog designation M24 points to its location in our Milky Way photo.

This cloud contains countless millions of stars and lies at a distance of about 16,000 light years.

It is aproximately 500 light years in diameter.

It is an easy target in binoculars and is visible to the naked eye on a dark night.

It's catalog designation M17 points to its location in our Milky Way photo.

This is another emission nebula which is a cloud of gas excited to glow by the ultra violet radiation of a very hot star in the midst of the brighest region. It is more commonly called the Omega Nebula but as I have never seen anything vaguely resembling the shape of this Greek letter, I will stick to the name that better represents what it really looks like.

M17 is about 40 light years in extent and lies at a distance of 5700 light years. It is an easy target in binoculars on a dark night.

It's catalog designation M16 points to its location in our Milky Way photo.