The Two Brightest Planets

Hi Everyone!

Just a quick note this time about some beautiful sunsets coming up. If you haven't noticed already, there are two especially bright “stars” decorating the sunsets these days. These are the two brightest “wandering stars” or “planets,” following the sun in its daily journey across the sky, and becoming visible in the brief time between the sunset and the setting of the planets themselves.

If you've been following along, you know that the higher one is Jupiter, and that it has been gradually creeping closer and closer to the sun for months now. It will continue to sink into the sunset as the weeks pass. (Sometimes Jupiter reverses its motion compared to the stars. That's called retrograde motion. But compared to the sun, Jupiter just circles the sky, slowly and steadily from east to west, passing the sun about once every 13 months.) The lower planet over the sunset is Venus, and it will continue to gradually creep higher and higher over the sunset as the winter turns to spring (for those of us in the Northern Hemisphere). Venus will soon become the glorious “Evening Star,” and it will stay brilliant and high over the sunsets for much of the spring and early summer, before turning around and sinking back into the sunset. (Compared to the sun, Venus does not make circles like Jupiter does. Instead, it swings back and forth between the front or the sunrise side of the sun, and the back or the sunset side. We never see Venus far from the sun in the sky. It's almost as if Venus is trapped near the sun for some reason.)

You may have noticed from the above discussion that Venus and Jupiter are currently on a collision course in the sky. Jupiter is heading towards the sunset and the sun, and Venus is rising up out of it. The two planets will indeed pass each other in the sky, long before Venus turns around and heads back in the same direction as Jupiter. You will be able to see them coming closer and closer together over the sunsets during the next couple of weeks, and on March the 1st they will have a “conjunction.” They will pass within about half of a degree from each other in the sky. That's about the width of the moon, and close enough so that you can see them together at the same time in a pair of binoculars. Depending on your longitude, you may or may not get to see the exact moment of closest approach, but you may still enjoy noticing them swap their positions in the sky. (The official time of exact conjunction is March 2, 2023, at 04:15 GMT, which for the continental United States is several hours after sunset on March the 1st. The planets will remain up for a while after the sun sets, but the delay is not enough. The exact moment of conjunction will occur after the planets set for all of the Unites States, although the West Coast will miss the event by mere minutes. However, you really don't need to care about the exact moment of conjunction, because the planets don't move that quickly. Wherever you live, just pay attention to the sunset on March 1, and you will see Jupiter and Venus extremely close together.)

This month's new moon will occur this coming Sunday, the 19th. If you are familiar with the lunar cycle, you can predict what will happen a few days later. That will be a good time to start looking for the lovely crescent moon to join Venus and Jupiter over the sunset. The moon will pass the sun on the 19th as a new moon, it will be visible over the sunset roughly two days later, at about the same time that it passes Venus, and it will pass very close to Jupiter on the 22nd. It will pass so close to Jupiter that viewers in Chile and Argentina may get to see the moon eclipse the planet (another lunar occultation!), although this event will occur close to the horizon just after sunset, and the duo will set themselves shortly thereafter. However, as with other lunar occultations, and the Venus-Jupiter conjunction, the rest of the world can still enjoy a close approach, even if their view isn't as dramatic as that of people in special places elsewhere. A day later, on the 23rd, you will be able to see the moon and the two planets in a nice alignment over the sunset, once again allowing you to visualize the “planet highway,” or the zodiac, or the “solar system in the sky,” depending on how you want to think about it.

The picture above shows the view of the sunset from mid-northern latitudes, about an hour after sunset. If you live in the Southern Hemisphere, just imagine the lineup tilted to the right instead of to the left. (Incidentally, my software adds some haze around the moon, so it looks full in the picture, even though it will really be a thin crescent … as it always is over the sunset.) If you know the constellations well, perhaps you can recognize the nearby stars. The group on the right should be familiar to most avid stargazers. The group on the left is a challenge, but it is still recognizable. It took me a few moments, but I was finally able to recognize it without looking it up.

That's it for now. Happy Viewing!

John