Moon at Perigee and More

Today (February 19th, 2011) the Moon will be at perigee (Moons apogee and perigee dates for the year 2011 click this link). If you don't know what perigee is, it is when the moon is at it's closest point to earth and because of this the moon will seem a bit larger than usual. Just looking at it with nothing to compare it to, you might not even notice this difference. At perigee the moon is approximately 356,375km (221451miles) from earth, and at apogee (it's furthest distance from Earth) it is approximately 406720km (252735miles) from Earth. Astronomers have a formula for calculating the exact distance of the moon at any point in time, but the average distance is 382500km (237700miles) from Earth.

When the Moon is at perigee there is a greater gravitational pull which contributes to higher tides or greater variation in the high and low tide. When the moon is at apogee it has less gravitational pull leading to lower tides or lower variation in high and low tide levels.

Not only is there a difference in size when the Moon is at perigee but the view of the moon is also slightly different than when it is at apogee. You're not going to go out tonight and notice it by looking at it because you've been looking at the moon all along as it's been getting closer. To see a chart of the Moons apogee and perigee dates for the year 2011 click this link, you can also enter in any year you want to see when it will be on any given year.


The slight difference of the view of our moon during Apogee and Perigee, we actually see up to 59% of the moons surface from Earth.

Also since we're on the topic of the Moon and the fact that it's full I'd like to bring up something real quick. When you see the Moon rising and it looks huge coming up over the horizon, it's not because it's any closer, it's actually because you have objects on the horizon to compare it's size to. It's an optical illusion. If you don't believe me, try this little trick. When you see the moon rising and you're thinking to yourself how huge it looks, hold up a ruler, or paper clip shaped like calipers (or and actual caliper if you have one), or a coin, anything to use to measure the size of the moon. Hold the object at arms length at the Moon, and take not of it's size. Later on at night when the moon is at the zenith (straight overhead) go back outside and hold the same object at arms length at the moon. Notice it's still the same size, if anything it might actually be a little bit larger at it's zenith instead of at the horizon, but it might not be noticeable. That would be because it's actually 4000 miles further when viewed at the horizon due to the radius of the earth. For more information in more detail, if what I said wasn't enough (haha) then go here to read more about it.

I would also like to bring up the full Moon leading to more crimes and people acting crazy. I feel I should do this while I'm on the topic of the Moon. We've all heard people reference bad things happening to the fact that it's a full Moon, but scientific studies (that's right, there was actual science involved in figuring if this is true or not) showed no such correlation between these acts and it being a full Moon. Social scientists speculate it's because people are more likely to notice a Full Moon rather than any other Moon phase when bad things are happening. It's something more memorable to someone at night when something crazy happens, you're less likely to make a correlation between a Quarter Moon and a crime that happened during it. Strange occurrences, crimes, births, murders, people acting insane happen all the time no matter what phase our moon is in but the full Moon get's noticed and causes more people to take note of it and talk about it.