The closest moon since 1948

On the 14th November we were treated to the closest moon to the earth since the 26th January 1948! It won’t get this close again until 2034, so if you missed it you’ve a bit to wait. But don’t worry, there’ll hardly be any difference to the next supermoon on the 14th December. So yes, it was a pretty historic event, however, the hype had people thinking there would be some astonishing sight when the reality was a little different. 

However, before we get into the details, this was my image of the moon taken in the early hours of the 14th November. 

The moon about 9 hours before its closest approach to earth since the 6th January 1948.

The moon about 9 hours before its closest approach to earth since the 6th January 1948.

How much closer was the moon compared to the Hunter’s moon?

If we compare the Hunter’s supermoon (write up here) on the 16th October 2016 (distance of 357,861 km) to the one on the 14th November (distance of 356,509 km), we see the moon came 1,352 km (840 miles) closer. 1

It’s not a lot closer and explains why visually you would be hard pressed to tell the difference between the Hunter’s moon in October and this one. Some might well have read that the moon was going to be 30 % brighter and 14 % larger than normal and that is true – but not compared to the Hunter’s moon in October which wasn’t normal. In fact Neil deGrasse Tyson humorously stated that the difference between the Hunter’s moon and the closest approach was equivalent to the difference between a 16″ and a 16.05″ pizza.

To illustrate this I made an animation of the two images I took (the first of the Hunter’s moon and the second of the moon’s closest approach). You’ll also notice what is known as the ‘wobble’ of the moon, which is very slight difference in angle of the face of the moon and you’ll also notice it’s hard to see the increase in size. 

Animation comparing the supermoon on the 16th October to that on the 14th November which was the closest since 1948 and until 2034.

Animation comparing the supermoon on the 16th October to that on the 14th November which was the closest since 1948 and until 2034.

Understanding how the orbit of the moon causes supermoons.

The difference between a full moon at its further point from earth and its closest point to earth is around 50,000km and easily apparent in the moon's size to us.

The difference between a full moon at its further point from earth and its closest point to earth is around 50,000km and easily apparent in the moon’s size to us. Image by Marco Langbroek.

So this 14 % larger and 30 % brighter moon that you read about is only true when compared to a normal full moon which is not at its orbit’s closest approach to earth. It’s important to understand that the moon does not orbit the earth in a perfect circle, rather an elliptical orbit which brings it close to earth at one point and then far from earth at the opposite point. We call the closest point, the moon’s perigee and the furthest point, the moon’s apogee. Sometimes the moon’s closest point of orbit coincides with the moon being a full moon (supermoon) and sometimes it does not (normal full moon). 

To show the difference in distance between the moon at its furthest point (apogee) and its closest point (perigee) we can come up with 50,153 km (31,164 miles) using the distance from earth on the 31st October and on the 14th November. At these distances it is possible to very clearly see the difference in size of the full moons as can be illustrated in the image by Marco Langbroek.

On a personal note

The last time the moon was this close my grandfather was restarting his life in Northern Ireland after fighting in World War 2 as a Spitfire pilot. In fact most of the world was again picking up the pieces and beginning to rebuild their lives after such a traumatic period of history. I think that’s what makes this closest approach of the moon more poignant to me. 

This is a quick video taken of the moon from that night that I’ll leave you with – my battle with the clouds while imaging!

 

My name is David Hamilton and I’m from Northern Ireland but currently living in Puerto Rico. I have a degree in Biochemistry and a M.Phil in molecular virology from Queen’s University Belfast. I write on some of my interests which range from virology, astronomy and science related subjects to history. Thanks for your interest!

References

  1. Moon distance calculator.

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4 Responses

  1. MarkGregory says:

    Way to go, David. Good write-up and photos. I enjoyed the science fiction type music accompanying your Moon and clouds video.

    • David Hamilton says:

      Thanks Mark, appreciate the feedback! I’m hoping to be able to capture the supermoon on the 14th December to add it to the animation… fingers crossed the clouds stay away!

  2. Liam Burns says:

    To say that this Nov 14th supermoon is the closest it’s been to the Earth since 1948 is somewhat misleading, you would be more correct to say that it’s the closest a *full* moon has been to the Earth since 1948. Perigee occurs during every lunar cycle. If a new moon occurs during perigee, it apparently is also called a supermoon. I may be wrong if the actual apogee and perigee distances have a cyclic change due to syzygy, the influence of the sun’s gravity on our system. If so, and there is significant cyclic change, my apologies.

    • David Hamilton says:

      Hi Liam,
      Thanks for commenting. Yeah there was some confusion around this and I had this conversation with someone else. We searched and found that the perigee on the 14th was actually the closest since 1948 (full moon or not). Using the moon calculator (link in references) it shows the perigee on the 26th January 1948 at 356,480 km and going through every year I was unable to find any perigee closer than that on the 14th which was 356,509 km (full moon or not).
      I know a lot of articles simply said it was the closest full moon but it turns out it was actually the closest moon since 26th January 1948 too.

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