Author: Fraser Cain

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Want to know the position of the Moon today? Or are you looking for some resources for the Moon tonight. The Moon is moving quickly around the Earth. This means that the time and location that the Moon will rise or set depends on your location on Earth. The phase of the Moon is always seen the same from everyone on Earth, but that changes from day to day.

To see what the Moon is doing today, you’ll want to consult our calendars of Moon phases. Just click the link for the year that you’re interested in, and then scroll down to the month.

• Moon Phase Calendar for 2008
• Moon Phase Calendar for 2009
• Moon Phase Calendar for 2010
• Moon Phase Calendar for 2011
• Moon Phase Calendar for 2012

If you’re looking for something more specific, like what the Moon looks like right now, check out this handy calculator from StarDate Online.

Do you want to find out the moonrise and moonset times from your location? Here’s a great tool, which calculates the moonrise/moonset times for the entire year based on your location.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

When you see the Moon way up in the sky, it’s hard to get a sense of perspective about how big the Moon really is. Just how big is the Moon compared to Earth?

Let’s take a look at the diameter first. The diameter of the Moon is 3,474 km. Now, let’s compare this to the Earth. The diameter of the Earth is 12,742 km. This means that the Moon is approximately 27% the size of the Earth.

What about surface area? The surface area of the Moon is 37.9 million square kilometers. That sounds like a lot, but it’s actually smaller than the continent of Asia, which is only 44.4 million square km. The surface ares of the whole Earth is 510 million square km, so the area of the Moon compared to Earth is only 7.4%.

How about volume? The volume of the Moon is 21.9 billion cubic km. Again, that sounds like a huge number, but the volume of the Earth is more like 1 trillion cubic kilometers. So the volume of the Moon is only 2% compared to the volume of the Earth.

Finally, let’s take a look at mass. The mass of the Moon is 7.347 x 10²² kg. But the Earth is much more massive. The mass of the Earth is 5.97x 10²⁴ kg. This means that the mass of the Moon is only 1.2% of the mass of the Earth. You would need 81 objects with the mass of the Moon to match the mass of the Earth.

We have written many stories about the Moon on Universe Today. Here’s an article about heavy construction on the Moon, and here’s what it would take to build a moon base.

Want more information on the Moon? Here’s a link to NASA’s Lunar and Planetary Science page, and here’s NASA’s Solar System Exploration Guide for the Moon.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

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The volume of the Moon is about 21.9 billion cubic kilometers.

Does that sound like a lot? For comparison, the volume of the Earth is 1 trillion cubic kilometers. In other words, the volume of the Moon is only 2% the volume of the Earth.

The interior of the Moon is composed of a crust, mantle and core. Astronomers think that the lunar core is about 350 km across, and accounts for only 20% of the size of the Moon. Most other planets and moons in the Solar System have a core that accounts for about 50% of their diameter. Outside the core is the middle mantle, and this is surrounded by an upper mantle.

Want to know the volume of Jupiter, or even the volume of the Sun?

Want more information about the Moon? Here’s a link to NASA’s Lunar and Planetary Science page. And here’s NASA’s Solar System Exploration Guide.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

Are you looking for a map of the Moon? As it turns out, there are plenty of resources on the internet that show the Moon’s topography, geology, and map out it’s many interesting surface features – such as craters, volcanoes, and surface rilles. These maps are the result of decade’s worth of satellite and telescopic imaging, lunar landing missions, and even manned missions to the Moon. The exploration is ongoing, and more data pours in with every passing year!

And it just so happens that we’ve compiled a list for your convenience and viewing pleasure. Below are a short collection of websites that provide comprehensive and even interactive maps of the Moon, as well as access to archival images and thousands of pictures of the surface. Click on the links and prepare to do a little exploring of your own!

• Observatorio ARVAL – This map of the Moon shows the location of all the seas and major craters on the surface of the Moon.
• Google Moon – This is one of the coolest tools you can use to see a lunar map. It has the locations of all the Apollo landing sites.
• USGS Moon Maps – The USGS has released a series of topographical maps of the Moon, and various images returned from the Clementine and other missions. If you want data… here’s where you’ll find it.
• Albedo Map of the Moon – Here are some maps of the Moon built up with 50,000 images gathered by the Clementine mission.
• Maps of the Moon – A collection of mosaic, labelled, and color-coded topographic maps provided by Professor Seligman (BA Astronomy and Physics, MA Astronomy, from UCLA).
• Moon-Edu – A resource collection of Moon interactive maps, images and sky-watcher/moon-watcher guides, provided by Wikispaces.
• Consolidated Lunar Atlas – an online collection of Lunar resources maintained by The Lunar and Planetary Institute, a research institute that provides support services to NASA and the planetary science community.

We have written many articles about the Moon for Universe Today. Have you ever wondered how long it takes to get to the Moon? And what is the distance to the Moon? You can also learn more about the Phases of the Moon, several Interesting Facts About The Moon. There’s also a really interesting article that answers the question, How Did the Moon Form?

For more information and resources about the Earth’s Moon, be sure to check out the websites of the various federal space agencies that helped contribute to our growing understanding of it. These include NASA’s Solar System Exploration, the European Space Agency’s The Moon – Our Neighbor and Destination: Moon, the Japan Aerospace Exploration Agency’s (JAXA) Lunar Exploration Program.

You can also listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

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Moonrise is the first appearance of the Moon over the Earth’s horizon.

Unlike the Sun, the rising of the Moon changes from day to day and location to location because the Moon is orbiting the Earth. The Moon takes just over 27 days to complete an orbit around the Earth, so you can actually trace its movement in the sky from hour to hour. This is why a lunar eclipse only lasts a few hours. That’s how long it takes for the Moon to pass through the Earth’s shadow.

The movement of the Moon comes from both the rotation of the Earth – which makes the Sun and the stars move through the sky, as well as the orbital speed of the Moon.

Where and when the Moon rise depends on your location on Earth. So you can’t just see a generic table of moon rise times.

Fortunately, the Internet comes to the rescue. Here are some links to some calculators that will help you find out what time the Moon will rise in your specific location.

• Moonrise and Moonset at Specified Location (NASA) – This calculator lets you punch in your specific latitude and longitude, year and month and then see a table of times that the Moon will rise and set for your location.
• Farmer’s Almanac – The Farmer’s Almanac website has a tool that lets you put in your ZIP or Postal Code and date and then see a list of moonrise and sunrise times. You can also browse by city. This is better if you don’t know your latitude and longitude.
• US Naval Observatory – This website lets you retrieve moonrise/sunrise time table for an entire year.

We have written many articles about the Moon on Universe Today. Here’s a story about building a moon base.

Want more information on the Moon? Here’s NASA’s Lunar and Planetary Science page, and here’s a link to the Solar System Exploration Guide.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

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Your weight on the Moon is 16.5% what you would experience on Earth. In other words, if you weighed 100 kg on Earth, you would weigh a mere 16.5 kg on the Moon. For you imperial folks, imagine you tipped the scales at 200 pounds. Your weight on the Moon would only be 33 pounds.

Why is your weight on the Moon so much less than your weight on the Earth? It’s because of the lower gravity on the Moon. Objects on the surface of the Moon experience only 16.5% of the gravity they would experience on Earth. And why does the Moon have such a lower gravity? Gravity comes from mass. The more stuff you have, the more you’ll pull with gravity.

The mass of the Moon is only 1.2% the mass of the Earth, so you might expect it to have only 1.2% of the gravity. But it’s only 27% of the size of the Earth, so when you’re standing on the surface of the Moon, you’re much closer to its center of gravity.

Because your weight on the Moon is about 1/6th your weight on Earth, but your muscles are still as strong, you could do some amazing things. You would be able to jump 6 times higher, or jump off the roof of a house and be unharmed. And here’s the coolest thing. Strap on a pair of wings inside an air-filled dome on the Moon, and you would be able to fly around with just your own muscle power.

Were you wondering what your weight might be like on Mars, or on Jupiter?

Here’s a cool calculator that lets you see what your weight would be on various worlds in the Solar System.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

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A quarter moon occurs when we see the Moon half illuminated by the Sun, and half enshrouded in darkness. Since the illuminated side points towards the Sun, it tells astronomers that the Moon and the Sun are separated by 90-degrees from our perspective here on Earth.

You can have a first quarter moon, when the Moon is halfway between a new moon and full moon. A new moon occurs when the Moon is directly in between the Sun and the Earth. From that perspective, the illuminated Moon is facing away from the Earth. A full moon happens when the Moon and the Sun are on opposite sides of the Earth. At that point, we see the Moon fully illuminated by light from the Sun.

When we see the first quarter of the Moon, that means the amount of the Moon that’s illuminated is increasing. Astronomers call an increasingly illuminated moon: “waxing”.

You can also get a last quarter moon, when the Moon is half illuminated, but the opposite side is illuminated. This is the halfway point between a full moon and a new moon. When the amount of the Moon that’s illuminated is decreasing, astronomers call this “waning”.

We have an article that explains all the phases of the Moon.

Want to know when the next quarter moons are going to happen? Here’s a chart from NASA that calculates the phases of the Moon over a 6000 year period. And here’s a cool calculator that shows you what the Moon is doing right now.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

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Hey, here’s a question: does the Moon orbit the Sun? Of course not, it’s a silly question. Of course the Moon orbits the Earth.

But wait a second and think. The Moon follows the Earth around the Sun in its orbit, and if you didn’t have the Earth, the Moon would really be orbiting the Sun. So can we say that the Moon is really orbiting the Sun?

No. But the case is pretty compelling.

First, take a look at the orbital velocity of the Moon. The Moon’s velocity around the Moon is a mere 1 km/second. But the Moon’s velocity around the Sun is 30 km/sec; same as the Earth.

And here’s something stranger. the Moon doesn’t follow a spiral pattern around the Sun, as you would think, but it always follows a convex path compared to the Sun. It’s not exactly a circle, but it looks like a 12-sided object with rounded corners. Check out this page to see what the Moon’s path around the Sun actually looks like.

Furthermore, the Moon experiences twice the pull of gravity from the Sun than it does from the Earth. So, does the Moon really orbit the Sun?

To figure out what orbits what, you need to know a term called the “Hill sphere” (named after the American astronomer George William Hill). This is the volume of space around an object where its gravity dominates the influence of gravity from a more distant object. If an object is orbiting within this Hill sphere, it’s a moon of the larger object.

You have to calculate the gravity from the primary body (the Earth), the gravity from the secondary body (the Moon) as well as the centrifugal force experienced by a particle moving around the Sun at the same orbit as the Earth. If the sum of those three forces is pointed towards Earth, the Moon is held in orbit. If they didn’t point towards Earth, the Moon would drift away from the Earth and orbit the Sun directly instead.

In other words, because the Moon actually orbits around the Earth; it’s orbiting the Earth. I know that sounds like circular logic, but stay with me. If the Moon wasn’t orbiting Earth, it would go into a smooth orbit around the Sun, and have no regular gravitational interaction with the Earth.

Of course, my good friend Phil Plait over at Bad Astronomy has a great explainer for this puzzler.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

Reference:
http://www.math.nus.edu.sg/aslaksen/teaching/convex.html