Taking MCAT CARS to Outer Space and Beyond


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Session 116

The recent landing of the Mars Perseverance rover reminds us that our universe is vast, as are opinions on the MCAT. As we always say here on the podcast, don’t bring your own bias. You can have a prediction, but be willing to change. And today’s passage is a great example of how you can apply that even to definitions.

As always, I’m joined by Jack Westin from JackWestin.com. Check out all their amazing free resources including a free trial session of Jack’s full course to see how it’s like learning from Jack Westin himself.

Listen to this podcast episode with the player above, or keep reading for the highlights and takeaway points.

Link to the article:

https://www.theatlantic.com/science/archive/2020/10/rogue-planets-milky-way/616897/

Some planets actually wander the galaxy alone, untethered. They have no days or nights, and they exist in perpetual darkness. In a kitschy NASA collection of travel posters for destinations beyond Earth, one of these cold worlds is advertised with the motto: “Visit the planet with no star, where the nightlife never ends.”

Astronomers call these worlds free-floating, or rogue, planets. They are mysterious objects, and a small group of researchers around the world is dedicated to studying them. Of the thousands of planets that scientists have detected beyond our solar system so far, only about a dozen are sunless and coasting on their own, somewhere between us and the center of the Milky Way. At least, astronomers think they are. “We are sure that these objects are planets,” Przemek Mroz, an astronomer at Caltech, told me. “We are not fully sure whether these objects are free-floating or not.”

Mroz has spent perhaps as much time thinking about these strange objects as anyone on Earth. He and his team just announced another finding—the smallest known rogue planet—today. The object is between the masses of Earth and Mars, a blip in interstellar space so relatively tiny that it might seem insignificant. But according to scientists’ best theories about the way planetary systems arise all across the universe, rogue worlds should exist.

The term rogue planet suggests that these objects desert their stars on purpose, striking out on their own to carve a new path through the Milky Way. In reality, rogue planets are usually kicked out of their star system, banished to a solitary existence circling the center of the galaxy.

The beginnings of a planetary system, including our own, are thought to be quite messy. As planets swirl into shape out of the cosmic fog surrounding a newborn star, they jostle one another around. The gravitational game of pool can shove planets toward the edges of a system, and even eject them altogether. Nearby stars can scramble planets too. Most stars are not born alone, but in clusters of dozens to thousands, and in such a crowded environment, a passing star with its own entourage of planets could whisk away a planet from another, keeping it for itself or casting it out into space.

[03:35] Changing Definitions

Today’s passage is a good lesson for knowing that definitions can change. You may have a prior definition for something going into a passage and the author could explain a different definition than what you’re used to. But that definition could even change within the passage.

“It's very important to not bring in your own bias. You can have a prediction but be willing to change.”Click To Tweet

[04:24] Paragraph 1, Sentence 1

Some planets actually wander the galaxy alone, untethered.

Jack says:

The author here is talking about planets that are wandering alone. The first sentence is the most important so make sure you really understand it because it’s establishing the topic and the direction we’re headed in. And if you’re lost at this point, you’re probably going to be more lost as you keep reading the paragraph.

[05:10] Paragraph 1, Sentence 2

They have no days or nights, and they exist in perpetual darkness.

Jack says:

Imagine, we all think of every planet as having daylight, but I guess that’s not the case here.

[05:56] Paragraph 1, Sentence 3

In a kitschy NASA collection of travel posters for destinations beyond Earth, one of these cold worlds is advertised with the motto: “Visit the planet with no star, where the nightlife never ends.”

Jack says:

It’s a cute little poster with a play on the word “nightlife” that most people think of it like going out to eat in restaurants and bars and stuff. And the nightlife never ends because there is no daylight.

[06:28] Paragraph 2, Sentence 1

Astronomers call these worlds free-floating, or rogue, planets.

Jack says:

These are known things and astronomers have a name for them. So it’s not some random thing.

[06:43] Paragraph 2, Sentence 2

They are mysterious objects, and a small group of researchers around the world is dedicated to studying them.

Jack says:

People are obviously interested in these mysterious things and people are researching them studying them.

[07:02] Paragraph 2, Sentence 3

Of the thousands of planets that scientists have detected beyond our solar system so far, only about a dozen are sunless and coasting on their own, somewhere between us and the center of the Milky Way.

Jack says:

There are only about a dozen of them.

[07:22] Paragraph 2, Sentence 4

At least, astronomers think they are.

Jack says:

Think they are sunless coasting on their own or they think they are where they are location-wise? We don’t know what the author means here yet so let’s keep reading.

[07:40] Paragraph 2, Sentence 5

“We are sure that these objects are planets,” Przemek Mroz, an astronomer at Caltech, told me.

Jack says:

They’re giving a name here from Caltech saying  they’re sure these objects are planets.

[08:03] Paragraph 2, Sentence 6

“We are not fully sure whether these objects are free-floating or not.”

Jack says:

This astronomer here is basically saying these are planets and they’re sunless. But they’re not sure if they’re free-floating.

Even though this is a science based passage, even though the author is discussing science, we could debate the science. We don’t know and it’s hard for students to understand this sometimes. But every piece of science concept you’ve ever learned was debated. We had to have experiments to support the hypothesis.

And so, it’s not out of the usual to predict or guess how these planets come about or how they work. Because we’re not able to go out there and actually observe them.

[09:42] Paragraph 3, Sentence 1

Mroz has spent perhaps as much time thinking about these strange objects as anyone on Earth.

Jack says:

The author is setting up some expertise here for this astronomer.

[09:54] Paragraph 3, Sentence 2

He and his team just announced another finding—the smallest known rogue planet—today.

Jack says:

The author is just expanding on his expertise that they found the smallest rogue planet. Rogue means, again, the planets are wandering alone. That’s usually what we think about when we say the word rogue where they’ve abandoned us.

[10:41] Paragraph 3, Sentence 3

The object is between the masses of Earth and Mars, a blip in interstellar space so relatively tiny that it might seem insignificant.

Jack says:

They’re just describing this new finding.

[10:54] Paragraph 3, Sentence 4

But according to scientists’ best theories about the way planetary systems arise all across the universe, rogue worlds should exist.

Jack says:

Well, it says it might be insignificant, and then it contrasts so we can assume it’s significant that it does exist.

[11:57] Paragraph 4, Sentence 1

The term rogue planet suggests that these objects desert their stars on purpose, striking out on their own to carve a new path through the Milky Way.

Jack says:

The author is expanding on what this rogue planet means right there. They’re out on their own. They’re not part of a star. And it’s interesting here that the author is setting it up that they’re doing this on purpose.

[12:23] Paragraph 4, Sentence 2

In reality, rogue planets are usually kicked out of their star system, banished to a solitary existence circling the center of the galaxy.

Jack says:

So it’s not really that they’re abandoning us but it’s that we’re abandoning it. It’s not really rogue even though the author defines it as being rogue. 

The normal definition of rogue is someone who has abandoned us. It’s really just like an excommunication like they’ve been excommunicated away from us. So the definition of rogue has changed. 

So if the MCAT asks, what does the author define as rogue? It’s not that someone abandons us. It’s that we abandon them. It’s been kicked out. Having a better interpretation and understanding of that could mean the difference between getting a question right and wrong.

[13:24] Paragraph 5, Sentence 1

The beginnings of a planetary system, including our own, are thought to be quite messy.

Jack says:

Here’s a little bit of explanation here on how these planetary systems are created. They’re messy so it’s not good.

[13:38] Paragraph 5, Sentence 2

As planets swirl into shape out of the cosmic fog surrounding a newborn star, they jostle one another around.

Jack says:

We’re given a visual of how all the planets get into orbit.

[13:55] Paragraph 5, Sentence 3

The gravitational game of pool can shove planets toward the edges of a system, and even eject them altogether.

Jack says:

The author is explaining why they’re getting kicked out. It’s the whole idea of gravitational pull.

[14:13] Paragraph 5, Sentence 4

Nearby stars can scramble planets too.

Jack says:

Again, the gravitational pull of other objects nearby.

[14:22] Paragraph 5, Sentence 5

Most stars are not born alone, but in clusters of dozens to thousands, and in such a crowded environment, a passing star with its own entourage of planets could whisk away a planet from another, keeping it for itself or casting it out into space.

Jack says:

The author here is explaining the birth of these planetary systems and when there’s lots of stars around, they can steal planets and eject them out.

[15:06] Main Idea

The point of the passage is just a discussion of these rogue planets and how they come to be. So if they ask you what the author believes, the best answer here would be something that says cautious or not sure. Because it’s not something that the author is committed to completely. They’re just throwing out ideas.

It’s not completely understood. And there are some MCAT passages that are very similar to this. They’ll present potential ideas for why something has happened. But as they’re saying it, they’re basically admitting that they don’t know. And it’s okay for the author to not know. That could actually be part of the main idea. And that’s an opinion that no one knows something.

And again, as we read, the definition of rogue changed. They went from they’re abandoning us to we’re abandoning them. And that’s that’s a very different interpretation of that word.

You’ve got to be flexible with these passages and be okay changing the definitions that you’re setting in your head as you go to the questions. And that’s what reading is all about.

“When you read, you become more aware of how vast our opinions are and how they can change so reading is a very good exercise of that.”Click To Tweet

Links:

Meded Media

Jack Westin

Link to the article:

https://www.theatlantic.com/science/archive/2020/10/rogue-planets-milky-way/616897/

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