04/22/2019 – Ephemeris – Earth Day

Ephemeris for Earth Day, Monday, April 22nd. Today the Sun will be up for 13 hours and 49 minutes, setting at 8:36, and it will rise tomorrow at 6:45. The Moon, 3 days past full, will rise at 12:24 tomorrow morning.

A good slogan for this Earth Day or any day is “Support your local planet.” As an amateur astronomer I look around the solar system at all the habitable planets. The Earth is it. Mars may be terraformed at great expense, that is made more earth-like. There may be life in the oceans of Jupiter’s moon Europa, or Saturn’s Enceladus, but they are not habitable for us. Terraforming (stopping and reversing climate change)  the Earth would be the easiest and much more practical. One look at our nearest neighbor Venus will show us our fate, hopefully in billions of years from now, a hell hole of heat and a crushing atmosphere. Our job is push-off that day as far as we can, and keep the Earth a blue-green oasis in the solar system.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Earth rising above the Moon’s limb from Apollo 8. Credit: NASA/Apollo 8

Mars had its day, but that ended about 3 billion years ago. Being half the size of the Earth, Mars cooled down, lost its magnetic field, so the solar wind stripped away most of its atmosphere and water. Credit NASA.

Europa, one of the four Galilean moons of Jupiter and easily seen in small telescopes, is slightly smaller than our Moon. Under that thick icy shell lurks an ocean with more water than all the Earth’s oceans. There’s probably volcanic vents like the black smokers in Earth’s oceans where a whole ecology of extremophiles could live like they do on Earth. Credit: NASA.

Enceladus, a small moon of Saturn spews continuous geysers of water from cracks in its south polar region indicating an ocean below its frozen icy exterior. Sampling the plumes with the right instruments may detect life on this small world without the need for drilling. Credit: NASA.

Is this our future? Venus had the misfortune of ending up too close to the Sun. It has a hellish landscape of nearly 900 degrees F, and 90 times the Earth’s atmospheric pressure. Its clouds consist of sulfuric acid. Talk about a runaway greenhouse effect and acid rain… Credit: NASA.