Posts Tagged With: earth

There are a lot of exoplanets around us

It is an exciting time indeed!
I stumbled upon this pic a year back, and I thought it was really cool – cause when you hear the figures of all the exoplanets, the numbers don’t really register (for me at least!). But this pic got it registered – we’re on to something big. And can you imagine the prospects of life on those tiny circles!
Never managed to retrace this pic from the first time I saw it a year ago, but a few days ago, I stumbled upon it again.
And here it goes! It’s gonna be an epic time!

ps. I’m thinking of studying Aerospace Eng, to make interstellar travel a reality – but really, to get on that flight to space (and to meet aliens).
Any thoughts on the prospects of majoring in this? See ya then!

exoplanets

Advertisements
Categories: Exoplanets, Misc, Planets | Tags: , , , , , , , | 2 Comments

Hey conglomerates, they’re in Mars too!

First day at the Geology Department. The three types of stones in the rock cycle are the igneous stone, sedimentary stone and the metamorphic stone.

The igneous rock happens because liquid magma hardens either above (extrusive rock) or under (intrusive rock) Earth’s surface. Obsidian is simply beautiful by the way!

Sedimentary rock is formed when layers of the sediments from the igneous rock as well as sand from the sea bed is packed under high pressure and temperature. It is compacted in a rock. It is lighter because it has more air spaces compared to the igneous rock, which is heavy and dense.Conglomerates, that’s the one Curiosity discovered on its journey to Mt. Sharp – more evidence to channels of water on Mars. The ones on Mars are essentially a bunch of gravel fused together…and since MOST of the gravel is rounded, that could only mean it’s worn out by water (their too heavy to be transported by wind),like the pebbles we find in rivers.

The metamorphic rock is formed when igneous rocks and sedimentary rocks are submerged underground (where rocks originated from in the fist place as magma) under high pressure and temperature, but it doesn’t melt. I swear we saw a migmatite, a rock at its last stage of metamorphism where it’s so close to melting (it escapes the melt though), though the department labelled it a gneiss. A feature of these metamorphic rocks is “foliation”: the alignment of crystals in the rock in a direction perpendicular to the stress/compressive force applied onto it.

Me and a shiny migmatite

Categories: Misc, Solar System | Tags: , , , , , , , , , | Leave a comment

Tides – the origins

It started off with mum and I watching the floods brought by Sandy on CNN and mum asked what’s the cause for waves. Well wind caused Sandy’s waves. But, Daily tides, high and low, are caused by the moon.

The accepted theory is the moon exerts a force of gravity on earth as the moon rotates earth (both the moon and earth rotate counter clockwise, but earth’s rotation is much faster). The parts of earth passed by the moon are pulled towards the moon, and when water is pulled, tides are formed! Yayy! Sounds easy right.

But, there comes this picture

– with the theory that the moon pulls the side closest to it the most, pulls the middle of the Earth with a medium force and the side furthest away with the least force. So the bulge of water on the left of the pic is pulled the least, appearing as a bulge as Earth is moved towards the right.

The sun comes into the picture as well, also exerting a pull on water. But, the moon’s pull beats the sun. Though the suns is massive, it’s too far away (F=GMm/r2, Newton’s Law of Gravitation) And if the moon and sun are on opposite directions to Earth, high tides become lower.

But then again, if the moon pulls pulls parts of Earth with different distances from it with different forces, each part would have a different acceleration. F=ma. The parts closest to the moon would accelerate the most (in the pic above, it would be the right end of Earth) and the opposite end (the left), the least. And so, with one end gaining acceleration compared to the other, Earth would be stretched and eventually pulled apart.

So, there has to be a restraining force. Earth’s gravity and its tension? Or a centrifugal force? Now what about a centripetal force?

If you want to end up confused (like myself), I suggest you read:
1. Tides and Centrifugal Forces by Paolo Sirtoli. Lots of physics explained here – with equations.
2. Tidal Forces and the Effects on the Solar System by Richard McDonald. Simpler physics and much easier to understand.
3. Tidal misconceptions by Donald. E Simanek. This is the most comprehensive to me, though let me warn you its quite long.

And then there’s the belief that tides don’t form on the equator. But I’ve seen it for myself, they do form! In fact, they’re semidiurnal tides (two equal high tides and low tides in a day). One high tide on each of the pair of “bulges” created. Check out ocean motion. to find out about types of tides at different latitudes on Earth.

I’ll keep you updated on tides once I piece everything together (and find some missing links, like I’m sure the moon’s orbit around Earth at at about a 5 degree angle to Earth’s ecliptic would have an effect as well). Let me know if you’ve got any ideas of your own!

And mum has two questions of her own:
1. Why isn’t paper pulled towards the moon when its so light.
To me, it is, but the effect is so small that you’ll never realize it.
2. Why do you get the highest tides on the full moon. This, I don’t know. So let me know if you do pleaseee.

ps. Here’s some videos on movements of the moon and of Earth.

Some cool stuff here!

Categories: Misc, Physics, Solar System, Uncategorized | Tags: , , , , , , , , | 1 Comment

Why Stars Move

20120629-172828.jpg

If you observe the skies at night long enough, you’ll realise that the stars move. You’ll see some constellations disappearing below the horizon and new ones appearing on the other side all in one night. Just like the way the sun and moon rises and sets. Well, It’s not the movement of the stars that causes them to rise and set on the horizon, but rather Earth’s rotation on its axis, around the sun.

Here’s a pic which summarises the rotation of Earth. It spins on its axis which is tilted 23.5 degrees to the perpendicular of its orbit around the sun (the Ecliptic). So, during the course of one Earth rotation (which is one day), it’s Ecliptic appears to shift north and south of the Celestial Equator at a tilt of 23.5 degrees.

20120627-194429.jpg

Source: Massey, S. and Quirk, S. 2010. Atlas of the Southern Night Sky Second Edition. Australia: New Holland Publishers

We see stars when Earth faces away from then Sun. Earth is always spinning; Throughout the night, some stars will disappear below the horizon on the West and new ones will appear on the Eastern horizon. And since Earth makes a complete orbital around the sun in a year as it travels on its ecliptic, we journey around the sun seeing all the different constellations in our skies as we, like passengers, are transported by our very own spaceship, Earth.

Categories: Observation Gear, Stars | Tags: , , , , , , , , , , | 1 Comment

Blog at WordPress.com.

%d bloggers like this: