General Question

flo's avatar

Was the moon gigantic on Friday June 9th, 2017?

Asked by flo (13313points) June 14th, 2017

Was it mentioned anywhere? Was it the largest size you’ve ever seen it?

Observing members: 0 Composing members: 0

11 Answers

Hawaii_Jake's avatar

Actually, it was termed a mini-moon. It was not a supermoon.

flo's avatar

At what time was it a mini moon? The size does change throughout the night right? At what time was it at it’s smallest and at what time was it at it’s largest?

Hawaii_Jake's avatar

I’m sorry. I don’t know.

YARNLADY's avatar

Strawberry Moon is great.

Call_Me_Jay's avatar

I found this

I am surprised at the size difference between far-moon and close-moon as shown in that link. It’s not radically different, but more than I expected.

I thought a big moon was just near the horizon where we have something to compare it with, instead of in the empty sky.

zenvelo's avatar

It was the smallest of the year because it is farthest from earth right now. The size of the moon in the sky does not change over the course of a single night. It was smaller compared to other full moons when it was closer to Earth.

Yellowdog's avatar

The illusion of the full moon being bigger on the horizon is not really understood—but it is more than just comparing it to distant objects on the horizon..

If you view a rising full moon while upside down, or even in a mirror, it doesn’t impress as being as big as when viewed directly.

And it is always smaller than we think—varying from being small enough to being hidden by holding a dime at arms length to a quarter at arms length.

LuckyGuy's avatar

The Moon’s apparent size only varies by a few percent. It looks larger when it is on the horizon compared to when it is directly overhead. but in reality is is slightly smaller . 2% if you live on the equator ~ 1% if you live at the same latitude as New York city.
Don’t believe it? Try this experiment. If you have a digital camera or a good set of photo-binoculars take a picture when you see it on the eastern horizon and then take one 6 hours later when it is directly overhead. Don’t make any changes to the camera zoom setting. Carefully compare the images and tell us which one is bigger. The image taken when it was directly overhead will be larger by a small amount. Why?
Because of basic math and trigonometry. In round numbers. The moon is 200000 miles away from the center of the earth. (Using the retroreflectors placed on the Moon during the Apollo missions NASA can measure this to a fraction of a millimeter but for our purpose right now we don’t need all the digits. With powerful laser or even a 200 Watt radio transmitter you can do it too.). The Earth is 8000 miles in diameter. (we also know this to a fraction of a mm as well but for easy math call it 8000 miles).
Now place a quarter on the table and a dime about a foot away. The quarter is the Earth. The dime represents the Moon. Now imagine you are standing at the edge of the quarter that is closet to the dime. That condition is the moon directly overhead.
Now imagine you are at the point on the quarter that is 90 degrees from the overhead position. That is the view you’d have when the moon is on the horizon. You can easily see that the dime is half the diameter of the quarter further away from you. At the equator that is 4000 miles/ 200000 miles or 2% but since you probably don’t live there, it will be less than that. (2% x cosine of the latitude but let’s ignore the details ) Assuming you live in Centralia IL you will see 1.4% difference.
If you are careful with your digital camera images you can see this yourself. You can use that difference to determine the diameter of the Earth! And it is all math you learned in junior high! Neat!

Yellowdog's avatar

Excellent information, LuckyGuy—best information I have ever seen on this topic in one place.

I have seen (aside from lenses and telephoto shoots) full moons rising and settings that appeared as big as the old Gulf gas station signs or Gold Medal flour—and itty bitty appearing full moons in the sky you can cover with a dime at arms length.

To the original poster, the full moon appeared as one of the most humongous he had ever seen, yet technically it was the smallest full moon of the year, Not his fault- though. The full moon varies in size but appears to our brains very different from reality in remarkable, little understood ways.

Thanks for the actual scientific/mathematical information on how we can test and calculate its actual optical size, LuckyGuy

Rarebear's avatar

What @LuckyGuy said.

Interestingly, as an amateur astronomer, I actually don’t mind the whole “supermoon” bullshit. If it gets people to go outside and look up I’m all for it.

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