When the Moon slips between the Earth and Sun this week, Slovak astronomer Vojtech Rusin will be ready on a hotel balcony in Cairns, Australia to witness his 19th total solar eclipse. StarStruck spoke with the National Geographic grantee, part of an international team, about what it takes to follow the stellar phenomenon.
• You’ve traveled around the world to observe solar eclipses. What’s different or special about this trip?
Total solar eclipses happen regularly around 75 times per 100 years. This eclipse is very important for studying the finest possible structure of the solar corona—the uppermost layer of the Sun’s atmosphere—which influences the Earth and its magnetic field.
• You’ve seen 18 total solar eclipses. Was any one particularly memorable?
My first one, in Africa, in 1973—it was like my first love. Everyone remembers their first love! I traveled through the Sahara from what was then Czechoslovakia to Niger. The eclipse lasted 6 minutes and 45 seconds, one of the longest durations ever observed.
• How have things changed in the four decades you’ve been studying solar coronas?
It’s changed so much. One thing is the imaging techniques have become much more
sophisticated, so we don’t have to take very heavy equipment anymore. Back in 1980 I traveled by truck from Czechoslovakia to near Bangalore, India; it was something like 10,000 kilometers (6,200 miles).
At each border the customs officers wanted to see documents for every item of the very heavy equipment we were carrying. We lost a lot of time. Now we have only a tripod and three telescopes that can be put on one mount, plus a laptop computer.
• You say this total solar eclipse will last 2 minutes and 3 seconds. How do you calculate so precisely how long the eclipse will last?
Everything is governed by the laws of gravity. If we know things like the exact positions of bodies, how satellites move around them and the distances between the Earth and Sun, the Earth and the Moon, we can make precise calculations.
• What makes the images you get from each total solar eclipse so different?
The shape of the sun’s corona is constantly changing, this change having a period of approximately 11 years (the solar cycle). It’s mainly affected by random distributions of magnetic fields on the solar surface entangled by the sun’s rotation. The corona features a plethora of remarkable objects like helmet streamers and polar rays. There are also coronal mass ejections that create rapid shape change lasting a few hours or so.