Exploring Orion, Episode 3

One of the many amazing features inside the great constellation Orion is the “Horse Head Nebula,” which is seen in the below photograph as the red area near the star Alnitak in the center of the photo.

Not far from the Horse Head Nebula is the Great Orion Nebula, to the upper right.

There is also a faint blue reflection nebula near the bottom left. All of these are active star-forming areas within our galaxy. Interstellar nurseries, in a manner of speaking, continue to birth new stars to this very day.

The Orion Molecular Cloud

Credit: astrophotographer David Rankin
Technical mumbo jumbo: shot with a Canon 6D, 200mm F2.8 lens at F4, 120 exposures at 300 seconds each

What is a Molecular Cloud?

Stars don’t spring up out of nowhere. They need matter to form, and the process generally happens like this:

Gas starts to gather together inside of one of these molecular clouds. Astronomers call this process “accretion.” This gas begins to spin and forms a disc shape. Science teaches us that as an object becomes more massive, it gains more gravity. So as this disc grows in size, it sucks in more and more gas because of its increased gravity. When we say more gas, we are talking about more than a minor case of indigestion. This is enough gas to create our Sun, all of the planets, all of the asteroids, and all of the comets in our solar system.

At some point, the center of this disc becomes very large and heavy. The pressure grows. Four separate atoms of hydrogen are pushed closer together, invading one another’s comfort zones. At first, they really don’t like this. They push against one another in an attempt to retain their own space and identity. They eventually are forced to concede that things are getting a bit awkward. They talk it out and all eventually agree that they are too close together and something needs to give. They shake hands, bond, and become part of a totally new atom!

A star is born! This bonding process releases a lot of energy. Whereas a star is fusing atoms, a nuclear bomb is breaking them apart—and a good indicator of the energy stored inside an atom and the energy being produced inside a star.

Stars exist in a delicate balance. The intense gravity of a star wants to make the star fall in on itself, but the outward pressure created by the atomic bonding inside the star pushes against this intense gravity and keeps the star stable. Later on, we will explore what happens when this balance is broken.

Where was this shot?

To gain a little perspective, the image below shows the location where photo above was taken.

See more Orion viewing tips to fully enjoy this amazing constellation!