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The word "tides" describes the regular rising and falling of the ocean's surface. Large lakes, such as the Great Lakes, also have tides, but the change in water level is only inches. Ocean tides are measured in feet.

Tides are caused by gravitational forces of the moon and the sun. The sun is huge, but it is 360 times farther from the Earth than the moon.

Even though the moon is much smaller than the sun, it has two times more influence on tides than the sun, simply because it is much closer to the Earth.

The moon's gravitational force pulls on water in the oceans and causes bulges that create "high ." The moon's gravitational pull is strongest on the side that faces the Earth. You might think that the opposite side of the Earth would experience a low , but that would be incorrect!

Amazingly, the moon's gravity creates a high on both sides of the Earth. As the moon's gravity pulls on the Earth, it pulls water into a on the side closest to it.

Meanwhile, on the other side of the Earth, there is another high created by the moon slightly pulling the Earth away from the still water on that side.

There are a few different types of special tides that occur depending on the of the moon. Spring tides are strong tides that occur when the Earth, the moon and the sun are in a line.

During these times, the combined gravitational pull of the moon and the sun is very strong. Spring tides occur during the and phases.

The Proxigean Spring is a rare, very high that occurs when the moon is unusually close to the Earth and in a . During this time, the moon is between the Earth and the sun.

"Neap tides" are weak tides that occur when the gravitational forces of the moon and the sun are perpendicular to one another, pulling on the Earth from different directions. Neap tides occur during the quarter moon .

Tidal facts:

Isaac Newton first explained tides scientifically in 1686.

The highest tides in the world occur in the Bay of Fundy in Nova Scotia, Canada.

Because the moon moves around the Earth, it's not always in the same place at the same time each day. So, the times for high and low tides change by 50 minutes each day.

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The moon has more pull on Earth than you might expect. Dive on in! This wonder is going to turn the tide of your mind.

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Today's Wonder of the Day was inspired by Darius from , . Darius Wonders, " What are stars made of. " Thanks for WONDERing with us, Darius!

Have you ever wanted something so bad that you've resorted to wishing upon a star? If so, you know it can be frustrating if that occurs to you in the middle of the day. It can seem like it takes forever until it gets enough for that first star to appear in the night sky.

Of course, you're probably waiting for night because of that old that goes something along the lines of "star light, star , first star I see tonight." If you love astronomy, though, you know that there's no need to wait for night. It's even easier to upon a star during the day!

Why is that? It's because during the day there's a large star shining brilliantly in the sky all day long. We call it the Sun!

Even though we usually think of the lights in the night sky as stars - and most of them are! - the closest star to us is our very own Sun. Perhaps because we see it so often and Earth revolves around it, we often take the Sun for granted. Without it, however, life on Earth would not be .

When it comes to exploration , have you noticed how you never hear about making plans to travel to the Sun? We suspect that's probably due to the fact that a spaceship would melt before getting anywhere close to the Sun.

Even if you had a spaceship that could somehow withstand the mind-boggling, heat of the Sun, you still wouldn't be able to land it on the Sun to explore. Unlike Earth, which has plenty of solid rock and soil to land on, the Sun isn't made up of the same kinds of materials.

Instead of solids (like rock and soil) and liquids (like water), the Sun is made up mostly of gases and . In fact, the Sun is comprised almost entirely of two extremely hot gases: hydrogen and helium. Stars also usually have trace amounts of heavier elements, such as oxygen, nitrogen, carbon, and iron.

When you look at the hot, shining Sun, what you see is the result of the main process occurring inside the core of the Sun: the conversion of hydrogen into helium in an ongoing, constant reaction similar to a hydrogen bomb. Even though the Sun is in a state of constant explosion, it consists of so much matter that it will take billions of years to exhaust all of its hydrogen "fuel."

Those ongoing explosions release huge amounts of energy into the universe. We call that energy electromagnetic radiation, and it includes both the heat we feel and the visible light we see.

So much energy is produced that the hydrogen and helium involved exist as a massive, glowing ball of that consists mostly of positively-charged ions with most of their electrons moving freely. Despite the explosive nature of the Sun, it appears solid because it's held together by its own massive gravity.

Not all stars in the universe are the same size or temperature. Even though our Sun looks massive to us, it's only a medium-sized star compared to others scientists have discovered and measured.

Even though our Sun is unbelievably hot, compared to other stars, the Sun is one of the cooler stars. Scientists have learned that a star's color corresponds to its temperature. The hottest stars are blue and the coolest are red. Yellow stars, like the Sun, are closer to red and are thus cooler, even though they're still incredibly hot!

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Today's Wonder of the Day was inspired by Darius from , . Darius Wonders, " What are stars made of. " Thanks for WONDERing with us, Darius! Have you ever wanted something so bad that you've resorted to wishing upon a star?