The Venus Clue

Did anyone watch the brilliant tango between Jupiter and Venus recently? It was in the western sky in early evening. These two planets are brighter than any star, brighter than any objects in the sky except the sun and moon.

Venus was the brighter of the two. At first Venus was below Jupiter. But Venus is closer to the sun than the earth and so moves around the sun faster. Last night Venus was above Jupiter. They were right next to each other at one point, but of course it had to be cloudy so I couldn't see it.

Until several centuries ago the night sky was very confusing. Everything seemed to move around the earth but there were several stars that appeared to "wander" among the other stars. These  wanderers became known as "planets", which means "wanderer". The planets all followed the same path, known as the Zodiac.

To make it more confusing one of these "wanderers" moved differently than the others. The other planets displayed retrograde motion. They were moving among the other stars when they suddenly reversed direction and moved backwards. The one that moved differently, the brightest of them all, would appear in the evening sky after sunset, and then switch to appearing in the morning sky before sunrise. This"wanderer " was called"Venus ".

With some insight, some "outside the box" thinking, and a little bit of geometry, there was a simple solution. These "wanderers" were planets like the earth. Everything did not revolve around the earth, it revolved around the sun. The planets were at different distances from the sun, and the closer they were the more quickly they moved around it.

The planets that underwent retrograde motion were further from the sun than the earth and were thus moving around the sun more slowly. The apparent retrograde motion is as the earth passes them in it's orbit, like passing a car on the highway.

Venus is closer to the sun than the earth, and thus revolves around it faster. We can tell that Venus is closer to the sun than earth because we can never see it in the middle of the night, only after sunset or before sunrise. The earth rotates eastward and so would logically revolve around the sun in the same direction. When Venus is in the western sky, after sunset, it is "catching up" to the earth in it's orbit around the sun. When Venus has overtaken the earth it appears in the eastern sky, just before sunrise.

I am certain that Venus provided the most important clue that the earth revolves, along with the other planets, around the sun.

TIME ZONE FOR THE MOON

With people going back to the moon it has been in the news about discussions concerning time on the moon. Whether the moon should have it's own time zone.

The only thing that makes sense is to use the moon's own time, not time relative to earth. Instead of time zones on the moon just use direct time, the position of the sun in the sky as measured with a sundial. The sun will rise at 6 AM, be directly overhead at noon, and set at 6 PM.

Of course the same side of the moon always faces earth. The moon revolves around the earth every 29 days so a day on the moon will last 29 earth days. As seen from earth the moon rises 50 minutes later each day and an earth day will last 50 lunar minutes.

As seen from the facing side of the moon the earth will always be seen in the same place in the sky. But it will go through phases just like the moon as seen from earth. This will make it easy to express latitude and longitude on the moon, by just describing where the earth is in the sky.

By the way one thing that I noticed and cannot see pointed out anywhere is that the phase of the moon, as seen from the earth, and the phase of the earth, as seen from the moon, must always add up to a full circle.