I’m going to prove how easy astronomy can be – and how dramatic. I guarantee that you will not fail. All you need is a mostly clear sky either Saturday night (March 28) or the following night, Sunday. It doesn’t even matter what time you venture out.
Either evening, start with the Moon. It’s in its gibbous phase, but never mind that. This happens to be the time of month when the lunar surface displays optimum lighting and shadowing. On Saturday between nightfall and midnight, that very bright star to the left of the Moon is Jupiter. On Sunday evening, Jupiter floats above the Moon.
That’s all you need to know. And those are our targets: the Moon and Jupiter – both together, brilliant and begging for exploration.
If you don’t own binoculars and all you have are your baby browns, then the next paragraph is all you get. To the unaided eye, neither object shows any detail. Typical lunar craters are 60 miles wide, like the distance from Albany to Lake George. But human 20/20 vision would only be able to discern something 200 miles across on the Moon’s surface. Thus, not a single mountain range or crater could be glimpsed until that fateful January night in 1610 when the first telescope looked at the Moon.
Nor could anyone guess their respective distances, although some early Greeks 2,300 years ago knew that the Moon is the closest celestial body. In truth, the Moon is a quarter-million miles away, while Jupiter, way off in the distance, is 1,500 times further. Expressed in terms of light travel, we see the Moon as it was one-and-a-half seconds ago, and Jupiter as it was 40 minutes ago.
Now dig out your binoculars or the small telescope that you haven’t used since forever. Unless you have image-stabilized binoculars, brace your elbows on a windowsill or a car roof so your hands don’t shake. The mere seven magnification of the binoculars gives you a better experience than Galileo’s. Suddenly you now see the lunar Apennine mountain range, and if it’s Sunday night the famous crater Copernicus will stand out left of center.
On Jupiter, all four of its huge Galilean satellites are easily visible in a straight line, both nights. One moon floats to the right of Jupiter; three are on the left. Saturday the orange highly volcanic moon Io is on the right, while the nearest moon on the left is Europa, the most likely place for life beyond Earth. Continuing further left you first come to Ganymede, the solar system’s brightest and largest moon, and then Callisto all the way on the left.
Sunday night, the superfast Io and Europa have traded places! Now Europa is on the right side of Jupiter, with its ice-covered surface floating over warm salty oceans. And the three moons lined up to Jupiter’s left are Io, Ganymede and Callisto. The latter two are now wonderfully close together.
This conspicuous metamorphosis in the Jovian satellites blew the mind of Galileo. It showed him that those moons were orbiting Jupiter at high speed, and instantly disproved the Church’s notion, which it had adopted from Aristotle, that the Earth is the center of all movement. Can you imagine being in Galileo’s shoes 405 years ago, being the only one on Earth who knew the truth?
If you have a small telescope, now all those moons are super-easy and Jupiter itself shows detail starting with horizontal dark belts like stripes on a bumblebee. And our own Moon, my goodness: It explodes with psychedelic detail. At the center right is the lunar Apennine mountain range. Following them curving down to the left, they culminate in two gorgeous craters: deep little Eratosthenes and then arguably the Moon’s very finest crater, Copernicus. At the bottom of the Moon hovers the rayed crater Tycho.
Copernicus is hidden in darkness Saturday night, but will be optimally, magnificently illuminated Sunday and again Monday nights. If you do own a small telescope, you’ll see its 11,000-foot-high rim, its gorgeous terraces stepping down to the flat bottom some 60 miles wide and the double mountain at the floor’s center.
Enticing stuff. Telescope, binoculars or nothing at all, this is easy astronomy, focused on targets that anyone can find.
Want to know more? To read Bob’s previous “Night Sky” columns, visit our Almanac Weekly website at HudsonValleyAlmanacWeekly.com.