The Antarctic Files: Part III

In late March (on our fall equinox), the Sun finally fell below the horizon. Coinciding with sunset, we were looking forward to seeing an atmospheric effect called a ‘green flash,’ but unfortunately it was overcast at the time. This green flash can be seen elsewhere in the world during sunset or sunrise over a clean, clear horizon (such as over the ocean on a calm, clear day) but can be more prolonged here due to the relative speed of the Sun. However we did distinctly see another atmospheric effect, that of the Earth’s shadow being cast across the sky. It is now dark, the stars are shining and, albeit faint, we saw our first glimpse of auroras (down here they are called the southern lights or, more properly, “aurora australis”) in mid-April.

In my previous entry, I promised that I would talk about the physics experiments that are taking place here. Since that time a major discovery was announced from data that was collected at the South Pole. There are telescopes here that, rather than looking at visible light, collect microwave frequencies from space. By observing these wavelengths of electromagnetic energy, scientists can learn more about something termed the “cosmic microwave background,” which is left-over energy from the Big Bang.

Dark Sector Lab at South Pole

By mapping this microwave data across the sky, certain characteristics (B-mode polarization) were found that were predicted to be the result of a rapid expansion of space, thus providing empirical evidence for the period of inflation following the Big Bang. It is a very exciting result for astrophysicists! The data used to make this discovery was actually collected a couple years ago from an older generation instrument called BICEP2, which will be followed up next year with a new generation telescope called BICEP3. The current microwave telescopes here include South Pole Telescope (SPT) and the SPUD/Keck Array.

It turns out that the South Pole is a great place to collect microwave radiation from space for several reasons. The remote location is isolated from local microwave sources. We are also on a plateau of ice at a high elevation (9301 feet), so there is less atmosphere in the way. Thirdly, the extreme cold also means the air here is very dry. Water absorbs microwaves (this is how a microwave oven works), so having less water in the air means the sky is more transparent to the frequencies of interest.

Of course, there’s plenty more science happening down here, but I’ll save that for next time. In the meantime, feel free to submit any questions you might have and I will try to answer them!

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