Where is the North Pole?

We have two North Poles. The most commonly known is the geographic north pole that sits at the top of the world. We also have the magnetic north pole, which is where your compass points when you are lost in the woods. But, the magnetic north pole is not static and in fact moves. (In Earth’s past, the north and the south pole have actually flipped so north is south and south is north.)

In this piece from the New York Times, we have a nice map from Jonathan Corum that shows the movement of the magnetic north pole over time. The map is a nice orthographic projection centred on the geographic north pole.

No matter where you go, there you are.
No matter where you go, there you are.

Of course the centre of the displayed map is not the north pole, as the designer cropped it to show the movement from Canada towards Siberia. What I really like is that the line is actually a series of dots. Of course we do not know if each dot is an actual measurement or an interpolation of the determined magnetic north pole, and that should be made clearer. But, I like to think that each dot is a point in the movement of the pole.

Credit for the piece goes to Jonathan Corum.

Quasi-satellite Asteroid Orbits

Scientists discovered Earth has a new quasi-satellite. It is an asteroid, and it does not orbit the Earth. But, because of the relationship between its orbit and Earth’s around the sun, it is involved in what NASA described as a dance with Earth. This is not Earth’s only dance partner, however, as we interact with a second asteroid as well. The screenshot of a YouTube video (from user britoca) shows how gravity choreographs the second dance.

Cruithne's orbit
Cruithne’s orbit

Credit for the piece goes to YouTube user britoca.

Supermoon Lunar Eclipse

Last night we experienced a total lunar eclipse here in Chicago. Unfortunately, significant cloud cover meant that much of the event went unseen. That was unfortunate, because eclipses are fantastic. To explain it we have this piece from the BBC.

What is a lunar eclipse
What is a lunar eclipse

And for those were either unable to see it or did not know about it, here is one of the photos I took.

During the eclipse
During the eclipse

Credit for the diagram goes to the BBC graphics department.

Credit for the photo is mine.