laura degroot

Here we still are

“You can keep your emotional heart open, so that it is breaking moment after moment after moment.

And beyond the unbearable, here we still are.

As you continue on the spiritual path, you are able to look more directly at the immensity of suffering without turning away, without being frightened of it.

The thing that frightens you about pain is that your heart breaks, and its hurts, and you can get so that its constantly hurting and constantly breaking — and behind it and within it is joy.”

- Ram Dass

Axial Precession

Magical thing no. 3: Axial Precession!

I was reading about the star Vega recently, and I came across a sentence that sounded kind of strange. It said: “Vega was the northern pole star around 12,000 BCE and will be so again around the year 13,727.”

Huh. I thought “The North Star” was the north star. It’s called Polaris, that literally means “the pole star.” What could cause a star, whose position is so reliable that it has been used for navigation since Late Antiquity[link], to change its place?

Well, news to me, it turns out that while the earth is spinning on its axis like this:

It’s also doing THIS:


This movement is called Axial Precession, and it happens pretty slowly. Earth does one of these rotations every 26,000 years.  I know what you’re thinking, “Oh big whoop, another space thing is happening too slow to matter to me.” Well guess what, the implications of this are major…ly interesting.

To understand the impact this kind of movement has, we need to understand exactly how the seasons work. 

Relative to it’s rotation around the sun, the Earth’s axis is titled by 23.5 degrees. Like this: 

During Earth’s year-long journey around the sun, summer is determined by which hemisphere is angled toward the sun. In the image above, summer is in the northern hemisphere, as the sun’s rays are hitting the northern hemisphere directly. It’s winter in the southern hemisphere, because those sweet sweet heat rays are hitting it at an angle, making them indirect and less concentrated.

This is what a year looks like:

So the axis of the earth does a full procession every 26,000 years. That means the side of the earth that is nearest to the sun will be in the opposite position, at the same time of year, 13,000 years in the future. On July 1st, 15015, it will be the dead of winter in Toronto. 

Gravitational Lensing

Hi friends! It’s been a while and I’m very excited to present… 

Magical thing no. 2: Gravitational Lensing!

We all know that gravity affects objects. You drop a plate, it falls to the ground, it smashes, you tear up a little bit because it startled you and you’re still kind of a toddler in a small place deep inside. Bam, that’s gravity. But I didn’t know until recently that gravity affects light as well, in some super dramatic and amazing ways!

Ever wonder why a black hole is black? All the time, right? If you wondered so much why didn’t you look it up? It’s fine, I’ll just tell you: A black hole is “black” because it has so much mass that it’s gravity is strong enough to pull all the light it might emit, or any light that comes close enough to it, into itself. Or in fancier (and more accurate) science words:

The event horizon is the point outside the black hole where the gravitational attraction becomes so strong that the escape velocity (the velocity at which an object would have to go to escape the gravitational field) equals the speed of light.1

But the effects of gravity on light are not limited to inside an event horizon. Gravity can act as a lens, changing the shape or apparent position of an object. This happens when an object’s light interacts with gravity on its way to an observer. This is called gravitational lensing!

Have a look at the diagram above. We have an observer looking at an object (Object A), and another object (Object B) situated past Object A. The light from Object B is distorted by the gravity of Object A. The result, from the observer’s perspective, is 2 images of Object B, on either side of Object A. This can be observed in nature, like the Einstein Cross, for example: 

Believe it or not, this is an image of one galaxy (centre) and one quasar behind it. According to Wikipedia:

The quasar is located about 8 billion light years from Earth, while the lensing galaxy is located at a distance of 400 million light years.

This is pretty magical in itself, but gravitational lensing doesn’t just create multiple images of an object. Let me tell you about my favourite effect of gravitational lensing, the Einstein ring. Imagine holding a wine class on its side and looking through the base. The imagery behind the glass would distort itself in a ring shape around the stem. WELL GUESS WHAT, this happens in space too.

[ dramatic pause ]

This beauty is called the Cosmic Horseshoe, and is an image of two galaxies, the galaxy in the foreground distorting the light from the galaxy behind it. Einstein rings exist in amazing numbers, and feel awesome to look at. 

Here’s one last image for your enjoyment, a collection of awesome gravitationally lensed smears around Abell 2218, a super massive group of galaxies.  

Magical, right?

( images not from Wikipedia found here )

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