rotation curve

Galaxies Demystified

/ Emma / 3 Comments

From the smallest of irregular and dwarf galaxies, to the most spectacular of spirals, to the most massive of ellipticals, there’s no denying that galaxies are incredible objects.

On this blog, we’ve covered a great deal of information about galaxies. We’ve followed their stories from the dawn of time in the universe to the present day, and we’ve explored all their different shapes and sizes, their masses, and the forces that shape their evolution.

If it seems like a lot, I understand.

So, let’s round up what we know and boil it down to a summary. Hopefully I can make galaxies more easily digestible!

(Though I do hope none of you actually try to eat one… 😉)

Continue reading →

Is Dark Matter Real?

/ Emma / 6 Comments

Here we are, people–it’s finally time to talk about dark matter!

I’ve teased this subject in my last few posts. We’ve discussed how the idea originated–with observations of the rotation of galaxies. We’ve touched on the question of whether dark matter could explain supermassive black holes.

What we have yet to do is take a proper deep dive into what the heck this stuff actually is. But there’s an even more important question…

How do we know it’s actually real?

Continue reading →

How Massive are Galaxies?

/ Emma / 3 Comments

If you needed to measure the mass of, say, a brick–or some other Earthly object–you could just set it on a scale. (Yes, scales measure mass, not weight.)

With galaxies, it’s not so easy! I don’t think anyone’s invented a scale big enough yet…

But if we can measure the mass of a galaxy, it brings us that much closer to understanding its origin. And that brings us closer to learning the story of the universe.

So…how do you measure a galaxy’s mass? And just how massive are they?

Continue reading →

How Massive is the Milky Way?

/ Emma / Leave a comment

Over centuries of philosophy and research, through the times of the classical astronomers to Galileo’s observations of the Milky Way, humanity’s understanding of our universe has evolved from a simple model of the sun and planets to a vast wheel of stars we now know as our galaxy.

And since the “discovery” of our Milky Way–or, more accurately, the discovery of what that hazy band of stars in the sky is–we’ve come to realize just how massive our home in the cosmos really is.

That scientific journey started with the Herschels’ mapping of what was then called the “star system.” Later astronomers began to realize just how far out from the sun the stars of our galaxy really reached. Determining distances across our galaxy was the first step to discovering its size.

Later, we began to understand its structure–mapping the extraordinarily thin disk, the chaotic central bulge, and the visible part of the halo, a sphere of stars that extends beyond the plane of the galaxy.

And since then, we’ve begun to master the next critical part of understanding our galaxy: its mass.

So, how massive is our galaxy?

Continue reading →