Category Archives: astronomy

The Seven Wonders of the Universe: Part 2

Earth

The Home Planet
Our home planet

You’d think we’d know all about our home planet. After all, we live on it. And, we do know quite a bit, just from walking its surface, sailing its oceans, and flying in its atmosphere. But, as any traveller knows, distance lends perspective. It gives us new insights into familiar places, simply by virtue of the fact that we are far away and can perceive home as a place “back there.” You see a bigger picture of your hometown when you’re far away from it. And, so it’s the same with our planet.


Voyagers view of Earth from the edge of the solar system.
Voyager's view of Earth from the "edge" of the solar system -- the blue dot in the right-most "ray" of light.

I’ve been working on a project focused on our planet’s climate,and so I keep returning to these pictures taken from well away from Earth’s surface. The first thing you notice is the water. And then, the clouds. Which, in our case, also speak of water, but in droplet form suspended in our atmosphere. Here and there the continents and islands peek out, and if you’re close enough, you can see the lush green of plant life. It’s home, but it’s also part of the larger universe. The same laws of physics and astrophysics that operate across the cosmos govern our solar system and home planet. What we observe here we can try to find elsewhere. And if we do find watery, lifebearing planets elsewhere, we may understand them better simply by virtue of studying our own world from a distance, too. And, in a sense, what we find at THOSE worlds, will also help us understand our own.

Earth is an amazing find in a universe populated mostly with galaxies studded with stars and nebulae. There are other planets out there, and most likely many with water and life. We haven’t found the life-bearing ones yet, but it’s only a matter of time. Until we do, that pale blue dot in the middle of the ray of light on the right is a rarity. It’s also one of my choices for one of the seven wonders of the universe.

We’re Mergiin UR galaxies…

Makin’ New Starzzzzz

NGC 4449 merging up a storm of starbirth...
NGC 4449 merging up a storm of starbirth...

That’s how we say that star birth is found everywhere in the universe, in “leetspeak.” In geekspeak, we say that this picture is an excellent example of starburst regions in a galaxy that lies 12.5 million light-years away. Hubble Space Telescope imaged galaxy NGC 4449 with the Advanced Camera for Surveys, in blue, visible, infrared and H-alpha light.

Starbirth is one of the great recycling mechanisms of the cosmos. It takes material just lying around in interstellar space (in just about any galaxy) and turns it into stars. It’s a process that’s been going on for nearly as long as there’s been stuff in interstellar space to use (more than 13 billion years, for those of you keeping score at home). It’s a complicated process because a cloud of stuff just hanging there in space isn’t likely to wake up one day and say “Gee, I think I’ll become a star.” Something actually has to happen to make the cloud particles (gases and some dust) start to clump up and whirl around in a crazy birth process. It needs a push of some kind to start those materials clumping together. Maybe like a gravitational heave-ho from a passing star (that’s an old favorite). Or, even better, a nearby massive star goes supernova and the outburst shoves the gas cloud molecules and dust grains together. If there’s enough stuff to push together and enough of a push, the process gets started.

For NGC 4449, the process was likely started by a merger with another galaxy. When galaxies mingle, their clouds of gas and dust can get compressed, and that can start up the starbirth nursery. If the mingling is widespread, you get pictures like this one: a galaxy ablaze with starbirth regions. No matter how you say it, that makes for some pretty spectacular images. Read more about it here.