What is the basic assumption of jeans Jeffreys tidal theory?

The Jeans-Jeffreys Tidal Theory: When Stars Almost Collided (and Maybe Made Planets)

Back in the day, figuring out how our solar system came to be was a real head-scratcher for astronomers. Enter Sir James Jeans and Harold Jeffreys, who cooked up a fascinating idea: the tidal theory. Basically, they thought a near-miss between our Sun and another star was the spark that created the planets we know and love. Now, this theory isn’t exactly the top dog anymore, but digging into its basic ideas? That’s like taking a peek into the history of how we think about the cosmos.

The Big Idea: A Star Walks Into the Sun’s Neighborhood…

The heart of the tidal theory is this: our solar system wasn’t a solo project. It needed a little help from a friend – or, more accurately, a passing star. Imagine this other star cruising a little too close to our Sun, close enough to cause some serious gravitational drama. That’s the core assumption right there.

What Else Did They Think?

Okay, so it wasn’t just about a random star showing up. Jeans and Jeffreys had a whole picture in mind:

• The Sun Back Then: Picture a young Sun, a massive ball of hot, glowing gas. Seriously huge.
• Size Matters: This intruding star? It had to be bigger than our young Sun. Think of it like this: the bigger star had more gravitational muscle to really mess with the Sun.
• Tidal Waves, Sun Style: As the star got close, its gravity started pulling on the Sun, creating massive tides on its surface. We’re talking epic proportions.
• Ejection Time: The tidal forces got so intense that a giant, cigar-shaped blob of hot gas got flung off the Sun. Jeans was pretty specific about this – one big blob, not a bunch of little streams. That’s what made his theory unique.
• Planet Assembly Line: This blob then broke apart, and each piece cooled down and clumped together to form the planets. The thick middle of the blob made the big guys like Jupiter and Saturn, while the skinny ends became the smaller planets. Neat, huh?
• Sun’s Lazy Spin: The sun was just rotating on its axis, not moving.

Jeffreys’ Twist: Maybe It Was a Collision?

Jeffreys took Jeans’ idea and added a little spice. He thought there were actually three stars involved: our baby Sun, a buddy star hanging out with it, and then the intruding star. According to Jeffreys, the intruding star smashed into the buddy star, and all the leftover junk from that collision eventually became the planets. Talk about a cosmic fender-bender!

So, What Happened to the Tidal Theory?

Well, as cool as it sounds, the tidal theory ran into some problems. For one, it had a hard time explaining how the planets got their spin. Plus, turning hot solar gas into solid planets? Tricky business. Eventually, scientists moved on to other ideas, like the nebular hypothesis and accretion disks.

Even though it’s not the go-to theory these days, the tidal theory was a big deal back then. It got people thinking about how star interactions could shape planetary systems, and it paved the way for the planet-formation theories we use today. So, next time you look up at the stars, remember that for a while, we thought they almost crashed into each other to make our home!