Foucault’s Pendulum

Over on the Astronomy Stack Exchange site, (obviously I follow the “new questions” feed in my RSS reader,) someone asked if it was possible, without knowing the date, to determine one’s latitude only by observing the sun. These are the sorts of random questions that grab me by the lapels and shake me until an idea falls out.

So my first thought was: Well if you’re in the arctic or antarctic polar circles you could get a good idea… when you don’t see the sun for a few days. Also, COLD. But that feels like cheating and doesn’t give a specific value. Which left me with this vague feeling that it would take me several months of observations. I could measure the highest position of the sun over the passing days and months and figure out what season I was in…

…wait, actually, I should be able to use knowledge of the Coriolis Force—our old friend that makes water circle drains different in the northern and southern hemispheres, and is the reason that computers [people who compute] were first tasked with complex trigonometry problems when early artillery missed its targets because ballistics “appear” to curve to do this mysterious force because actually the ground rotates . . . where was I?

Coriolis Force, right. But wait! I don’t need the sun at all! All I need is a Foucault Pendulum and some trigonometry… Here I went to Wikipedia and looked it up—which saved me the I’m-afraid-to-actually-try-it hours of trying to derive it in spherical trig… anyway. A Foucault Pendulum exhibits rotation of the plane of the pendulum’s swing. Museums have these multi-story pendulums where the hanging weight knocks over little dominos as it rotates around. Cut to the chase: You only need to be able to estimate the sine function, and enough hours to measure the rotation rate of the swing-plane and you have it all; northern versus southern hemisphere and latitude.


Steve is not an aurora

This means that STEVE is not likely to be caused by the same mechanism as an aurora, and is therefore an entirely new type of optical phenomenon – which the team refer to as “skyglow”.

~ Matt Williams from,

Aside: “Steve” started as in-joke reference by some dedicated Aurora photographers. It was later backronymed.

I particular love this type of discovery. Looking at the shape of the visual phenomenon—it’s a straight-ish thin streak—I bet this is realated to certain types of mythologies and stories…


First habitable exoplanet

The first Earth-sized exoplanet orbiting within the habitable zone of another star has been confirmed by observations with both the W. M. Keck Observatory and the Gemini Observatory. The initial discovery, made by NASA’s Kepler Space Telescope, is one of a handful of smaller planets found by Kepler and verified using large ground-based telescopes. It also confirms that Earth-sized planets do exist in the habitable zone of other stars.

Mark you calendar: April 17, 2014. First confirmation of the existence of a HABITABLE planet… Temperature, gravity, rocky (like the Earth)… A. HABITABLE. PLANET. I got chills reading this.


How’s That Space Program Coming Along?

A rather large asteroid will be swinging by on Friday. If we were hit by a rock of this size, it would be a regional disaster; Destruction on the scale of a large city, with major regional earthquake and weather side effects.

Our home planet is due for a record setting space encounter on Friday (Feb. 15) of this week, when a space rock roughly half a football field wide skirts very close by Earth at break neck speed and well inside the plethora of hugely expensive communications and weather satellites that ring around us in geosynchronous orbit.

~ Universe Today

The B612 Foundation is working to build a space telescope specifically designed to locate and track asteroids that pose a threat to the Earth:

If you knew you could do something to literally save the world, would you? We have taken on the audacious mission of doing just that. Our goal is to hunt asteroids that could hit the Earth and potentially cause human devastation.

~ B612 Foundation

How long ago did we learn of DA14 and its impending close flyby of Earth? DA14 was discovered on February 13, 2012, just one year in advance of its close flyby of Earth. Had it been on a collision course with Earth on February 15, 2013, there would not have been enough time to prepare a mission to deflect it. While we would have been able to accurately predict its impact location on Earth, our only possible response would have been to evacuate the area and hope for the best.

~ B612 Foundation from,