Ok, I'm finally at the last two articles from the September IGY Bulletin, then I can move on to October and be in the right month again.
Aurora and Airglow Program
The altitudes of these two atmospheric phenomena are about 150 km for the aurorae and 100 km for the diurnal airglow, respectively, shown in a graphic from an earlier post, corresponding to the middle atmosphere and the lower ionosphere. (Recall that 1 mile = 1.6 km, or 1 km = 0.6 miles.)
The airglow is a faint optical emission due to interactions of sunlight with atmospheric chemistry. On the other hand, aurora emissions are driven by atmospheric reactions with energetic electrons in the magnetosphere that originated in the solar wind. I've only seen one aurora -- in 1994 I think, keying that to a family trip where we had seen a Toronto Blue Jays (younger son Sam's favorite team at the time) game right before the end of the strike-shortened baseball season -- when we were camping outside Ithaca, NY. My older son Max remarked on some lights in the sky, which I attributed at first to some spotlight, but was eventually convinced otherwise. Ha ha, that reminds me that Max also noticed a total lunar eclipse that I was unaware was going to happen when we lived in Germany during my first sabbatical in 1989-90; that must have been on Feb. 9, 1990. Ok, now that I am on eclipses, two years from today there will be an annular eclipse of the sun in the southwestern Southwestern U.S., and in 2.5 years a total eclipse of the sun visible in the northwestern part of my state of Pennsylvania. Start planning.
Anyway, the Bulletin article discusses plans to observe aurora during the IGY by photographing the whole sky with 29 cameras deployed in high northern and southern latitudes. With film(!), if you young folks know what that is. And here is a cool word from the article: ascaugraph - an instrument for the semi-automatic reduction of all-sky camera films, constructed for the IGY. I can't even find that word by googling.
The aurora were also to be observed visually at 120 U.S. Weather Bureau (employer for my second summer job, I'll save that for another time), and 56 volunteer stations. Yay for citizen science. Spectrographs (to look at emission colors, or spectra) and other instruments were also to be used.
Here is a more recent (Feb. 18-19, 2014) spectacular video display of the Northern Lights in Alaska (you can turn the music down):
Rocket Program
Experiments discussed in other articles in this issue of the Bulletin for studying solar activity, ionospheric physics, geomagnetism, aurora and airglow were ground-based or made low in the atmosphere. Rockets as a research tool would also allow observations to be made from higher altitudes, without the hindrance of atmospheric screening. Sounding rockets (exploring vertical stratification) were to be used during the IGY to make observations of the atmosphere, ionosphere and magnetosphere at different latitudes, but especially from the newly established complex at Ft. Churchill, Canada, located in the middle of the auroral oval zone where the aurora are most prominent. The U.S. Department of Defense and the Canadian government cooperated in establishing the launching complex and associated instrumentation at Ft, Churchill. Pre-IGY tests were make with 19 small rocket flights and 5 Aerobee rocket flights.
Many Aerobees were launched from the White Sands Missile Range in New Mexico. Check out the history of the Aerobee rocket in this video from the New Mexico Museum of Space History:
No comments:
Post a Comment