Bernard Reim
There was a great chance for most of the country to gain this greater context recently on May 9. You didn’t even need to stay up late at night, but you did need a telescope and a solar filter to see and appreciate this fairly rare event. I watched the event for about 5 hours, even though passing clouds hid the sun for over half of that time. The two best moments, first contact and last contact were also clouded out, but it was still a joy to watch it and share it with a few dozen other interested people. I also looked at the sun through two different telescopes with built-in hydrogen alpha filters, which allowed us to see any prominences over the limb of the sun and any dark filaments and hotter and whiter regions called plage on its surface.
Only a small percentage of people in this country or the world have been fortunate enough to even glimpse the sun much less study it for any length of time through one of these hydrogen alpha filters. I had plenty of time that Monday to do just that. It gives you a much greater sense of how we really are in direct contact with the sun at all times through the dynamic solar wind that always rushes over and around us at nearly one million miles per hour and generates cascading cosmic rays, hundreds of which pass through us every second. The sun spins on its axis every 28 days and you can see the prominences rise and fall in real time as they follow the powerful magnetic field lines of our local star. It would take about 10 minutes of continual looking to notice any change, but that gives you a much better sense of the majestic power of the sun and its size at 109 earth diameters and our distance to the nearest star.
It was all unfolding right there in front of us, only 8 minutes away at the speed of light, but it was changing imperceptibly slowly unless you recorded it and played it back faster. Mercury was flying right along at 30 miles per second, traveling its full width of 3,000 miles every minute and 40 seconds. And still we couldn’t notice anything, it was almost as if we were all frozen in time, knowing full well that something spectacular and rare was happening very close to us in space, but we could simply not grasp the full impact of this amazing phenomenon.
Mercury’s sharp and dark, perfectly black little circle, about 150 times smaller than the sun’s huge and luminous disk, contrasted nicely with a large group of much less sharp sunspots a little above our first planet. The sunspots had a grayer area around them called the penumbra and a darker and cooler region in their center called the umbra. They always occur in pairs with a North and South Pole since they are magnetic phenomenon wrapped up with the solar chromosphere.
Staring at the sun for that long also gave me a much better sense of its great power as it really does very generously provide for all life on earth. Every single second our very average sun is turning 700 million tons of hydrogen into helium, releasing 4 million tons of pure energy. We only receive one billionth of all that energy, or about 1 kW per square meter of our surface, but that is sufficient if we can capture and store it effectively.
Carefully watching Mercury’s motion across the face of the sun for all that time also made me think about what gravity really is, the force that keeps not only Mercury but also the earth and all the thousands and probably billions of other planets in our galaxy in perfect orbits around their parent stars. As Einstein proved, gravity is simply the curvature of space-time. As John Wheeler stated, mass tells space how to curve and space tells mass how to move.
A perfect example of that is the precession of the orbit of Mercury. That was a mystery for over 200 years as the best minds on Earth could not figure it out, thinking it had to be some kind of object affecting its orbit that they could never find. That’s because it didn’t exist. The huge mass of our sun warps the actual space through which Mercury is always moving, which exactly explains the precession of its elliptical orbit. So we were seeing the effect of the very space-time curvature of the universe itself playing out right in front of all of us!
Three bright planets now dominate our evening sky. Mars was at its best in late May and is still much brighter and larger and redder than usual. Look for some surface features and the polar icecaps through a telescope. You could even spot one or both of the Martian moons now. We are already leaving Mars farther behind in or faster orbit around the sun.
Look for the softly glowing golden orb of Saturn as it now emerges right at sunset, reaching opposition on the third of June and remain in the sky all night long. If the shadow cone of the earth were long enough, it would hit Saturn that day. However, our shadow is only about a million miles long and Saturn is nearly one billion miles away, which is a thousand times farther than our shadow reaches into space. Both Mars and Saturn can be seen fairly close to each other now, with Mars in Libra and Saturn in Scorpius near Antares, an orange super-giant star fully 700 times larger than our sun. Watch the nearly full moon pass near Mars and then Saturn on June 17 and 18. Notice that Mars is now six times brighter than Saturn, which is very unusual. Jupiter is moving in its direct, eastward motion again in the eastern part of Leo the Lion. Mercury reappears in our eastern morning sky 30 minutes before sunrise. It will only get 7 degrees high so you may need binoculars to see it. Look for the very thin waning crescent moon right next to Mercury on June 3, the same day that Saturn reaches opposition.
June 3: The very thin crescent moon is just below Mercury this morning half an hour before sunrise.
June 4: On this day in 2000 the Compton Gamma Ray observatory re-entered our atmosphere. It discovered many amazing things about our high energy universe including about one very powerful gamma ray burst every day for its 10 years in orbit. New moon is at 11 p.m. EST.
June 5: On this day in 1989 Voyager 2 flew by Neptune, transmitting live pictures of this planet. On this day in 2012 the last transit of Venus across the sun took place that most of us will ever see. The next one is not until December of 2117.
June 9: The waxing crescent moon will be near Regulus in Leo tonight and near Jupiter the next night.
June 12: First quarter moon is at 4:10 a.m.
June 16: On this day in 1963 Valentina Tereshkova became the first woman in space.
June 17-18: The moon, Mars, and Saturn will create a wide, flat triangle in our sky.
June 20: Summer starts at 6:34 p.m. This marks the longest day for us in the northern hemisphere and the shortest day and the beginning of winter in the southern hemisphere. Full moon is at 7:02 a.m. This is also called the Strawberry or Rose Moon.
June 26: On this day in 1730 Charles Messier was born. He was a French comet hunter that developed a catalog of 110 objects that many amateur astronomers can find. He also discovered about a dozen comets.
June 27: Last quarter moon is at 2:19 p.m. EDT.
June 28: George Ellery Hale was born on this day in 1868. He successfully designed the 4 largest telescopes in the world from 1898 through the Mt. Palomar 200 inch in 1948.
June 30: On this day in 1908 a comet or asteroid exploded 5 miles above Tunguska, Siberia with the force of 20 megatons of TNT, or about 1,000 times the force of the first atomic bomb. About 80 million trees were leveled over an area of 1,000 square miles and no crater was ever found. A similar event just occurred 105 years later over Chelyabinsk, not far away. This one was a chunk of rock about 65 feet across that exploded about 15 miles up and no one was killed, but it could have been much worse. An event like this happens about every 50 years.
— Bernie Reim is an amateur astronomer and teaches astronomy lab courses at the University of Southern Maine.
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