SpaceMika

I love orbital dynamics. The math & physics is beautiful, complex, and precise.

I loved orbital dynamics when I first studied it as a wee physicist, but research into surficial cracks on Europa caught my heart and never let go.

Cassini’s mission is extended, and her dance to pull of another 7 years of orbits with less than a quarter tank of fuel is gorgeous.

Spin in an office chair with your arms & legs sticking out, then pull your limbs in tight to spin faster. If you watched Vancouver’s Spring Olympics, you saw figure skaters slow down a spin by extending a leg, then speed up by simply withdrawing the leg. This has to do with the moment of inertia — the mass distribution impacts how an object will rotate. When more mass is farther out, things spin slower than when the same mass is closer to the axis of rotation.

When really big subduction earthquakes happen, a thick, heavy chunk of the ocean crust pulls in closer to the center of the planet. This redistribution of mass makes the Earth turn a little faster. After the Chile quake, our days are about 1.26 microseconds shorter than they used to be. This is a permanent change to our global moment of inertia.

But megaquakes aren’t the only impact on the length of a day — the moon provides a gravitational yank to slow us down. Over time, the moon is slowing the Earth through tidal friction, while simultaneously the moon is getting sped up by the Earth (conservation of momentum!), thus moving to a slightly higher orbit. Given billions of years, eventually days and months will be the same length, with the same side of the Earth always facing the same side of the moon. More details on this by the Bad Astronomer.

I tease that planetary formation is a delightfully broken science, one where every exoplanet we discover seems to poke an unpatchable hole in the latest and greatest theory.

In contrast, I am astounded by the beautifully precise mechanics of orbital dynamics, a science that had its last greatest breakthrough with Kepler hundreds of years ago. The story of tidal motion cracking Europa’s ice crust brought me great delight when I first saw it (technically here) — a theory that can be so simple yet so exactly modeling our observations can only be described as graceful. I love it.

So I admit that the latest “exoplanet breaks rules as we know them!” caught me a bit by surprise when it wasn’t the planetary formation mucking about, but the orbital evolution.

And while we’re talking about astronomical bodies, the joy that is LookUp now has a twitter account for tweeting an object (@lookupastro Mars) and it will tweet back the current position and a link to more info (Mars (Planet) is at RA 06:05:01.232 dec 23:33:06.130 More info http://bit.ly/eQ0dy) Admittedly, it’s only really usefully for the sort of folk who have a twitter account set up with their cellphone, but I can see it leading to all sorts of impromptu object-hunting during the next observation night at my university.

Will it count as breaking my twitter rules if I start tweeting for data?

On a more cheerful note, this dude photographed a fireball meteor through a telescope!

It’s officially over 30C in Vancouver.

In other news, the newest images from the Lunar Reconnaissance Orbiter show the Apollo landing sites. Oooooooh!

So, you thought Saturn’s rings were flat, did you?

It’s been crazy-busy around here recently, but I always have time for neat astronomy.

Shuttle, Hubble, and Sun

Wow, this is a really cool image.

In Vancouver, the action will be at the H.R. MacMillan Space Centre on Saturday, May 2nd from noon until late. The Royal Astronomical Society of Canada is hosting a free public outreach event including night observations with telescopes (weather permitting) and Dr Aksel Hallin’s talk on the Sudbury Neutrino Observatory.

There’s a really nice article up on black holes — eloquent, artistic, and accurate. The punchline? Black holes may have an upper limit, where if they get too big (a few billion times the mass of the sun — the Milky Way black hole is only a few million times the mass of the sun) all the gas whirling around just outside the event horizon will be so energetic that the radiation will push away any additional mass.

All the space lists have been jumping with news of the very small rock expected to create a nice light show in Sudan tonight, but I haven’t actually seen confirmation that the prediction was correct. It’d be neat if it was.  We’re famously bad at spotting Near Earth Objects, and even when we do see them we rarely have enough observations to make an orbital determination (although the Summer Science Program has switched to helping a tiny bit with that).

It’s a bit wack that the coverage all seems to focus on sensationalism (“Fireball to hit Africa!” “Asteroid impact tonight!”) when the whole point of the bulletins is to prevent observations from being reported as missiles or UFOs, and the real story is if this prediction is correct or not (the last one was a “not”).

Update: Yup, it hit. There’s a cookie-laden site with a photo, while I think the Times Online wins the contest for most overblown title.