A Solar Eclipse and a Lunar Occultation!

I'm going to start this month with some sad news. This will be my final newsletter. What I've been trying to do for the last few years hasn't been working out for me, and what I'll do next is still far from clear. My science education website will continue to exist, and hopefully grow, but regretfully I don't think I can spare the time and effort any longer to continue to write this newsletter.

If you'd like to stay up-to-date on events in the sky, I can recommend Sky & Telescope's Sky at a Glance feature, and Dominic Ford's In-The-Sky website. I also enjoy the monthly video updates by youTuber Alyn Wallace, although he is an astrophotographer by profession and his What's in the Night Sky videos are focused mostly on good opportunities for making beautiful photographs, rather than on showing things to kids. (But if you want to see some gorgeous examples of things you can do with a camera, be sure to check out his professional page.)

2023 Eclipses

Tomorrow we begin the 2023 spring eclipse season in dramatic fashion, with a total solar eclipse! Unfortunately for most of us, this one will only be visible in Australasia. If you'd like details for this event, including a visibility map and timetables for your specific location, I recommend Time and Date's web page.

The corresponding lunar eclipse will occur half-a-moon-cycle later, on May 5th. If you study my eclipse tables in detail, you may notice that solar and lunar eclipses tend to occur in a complementary fashion. Solar and lunar eclipses tend to occur in pairs, one of each in each “eclipse season.” And as the lunar eclipses become less dramatic, the solar eclipses come out of hiding (so to speak), and vice versa. We just finished a couple of years of dramatic lunar eclipses during which time the solar eclipses were only visible at the poles, and now that the solar eclipses are becoming more prominent on the calendar and in the world, the lunar eclipses are going into abatement. The lunar eclipse in a couple of weeks will only be penumbral, meaning that the moon will never actually enter the full shadow of the Earth. However, it will come close enough to the edge of the shadow that you might notice a dimming of one side of the moon, the side closest to Earth's shadow. It won't be dramatic, but it might be a fun challenge to see if you can notice the dimming. For more details, again I recommend Time and Date's web page covering the event.

Next fall, during the second eclipse season of 2023, we will see another spectacular solar eclipse, and another mild lunar eclipse. The Great American Solar Eclipse on October 14th will be visible across a large portion of the western United States, as well as most of Central America and the Amazon basin, so many of you reading this may want to mark October 14 in big red letters on your calendars! Solar eclipses come in various kinds, and this one will be annular. Do you remember the last time that the press got excited about a “supermoon”? Sometimes the moon is a little bit closer than usual, and looks a little bit larger in the sky. If we happen to have a solar eclipse at this time, then the moon will be large enough to obscure the sun completely, and we will have a total solar eclipse. But “minimoons” can also happen. Sometimes the moon is a little farther away than usual, and looks a little bit smaller in the sky. These differences in size are not large enough that you would ever notice it in the sky … except when the moon crosses paths with the sun. When we have solar eclipses at the time of a “minimoon,” the moon isn't quite big enough to cover the sun completely. Even if we see the moon pass directly across the center of the sun, it still leaves a small ring of the sun exposed around the circumference of the moon. This “ring of fire” is the distinguishing feature of an annular eclipse, and this is what many viewers in the Americas will get to see next October.

The lunar eclipse of the 2023 fall eclipse season will occur two weeks after the solar eclipse, on October 28th. This one will not be penumbral. The moon will actually enter the Earth's shadow … but just barely. This will technically be a “partial” lunar eclipse, but it will be a brief and shallow partial eclipse. Again, it won't be very dramatic, but it might be a fun challenge to see if you can catch sight of it.

Spring Planets

In the evenings this month, Venus continues to dominate the sunset scene. Go outdoors just after sunset on any clear day in the next few months, face west, and you should have no trouble finding Venus. (Venus is so bright that if you know just where to look, you may even be able to see it while the sun is still up!) Venus will rise even higher over the sunset for the next couple of months, cresting in early June. Mars is present in the evening sky as well, above and to the east of Venus, but it is fairly dim. It will gradually approach Venus until they meet in June, at which point the pair will descend together into the sunset for the following couple of months.

Over the sunrise this month you can find Saturn. Jupiter is currently passing the sun, and will rise higher over the sunrise as the month goes on, but it will probably not be easily visible until May. After Jupiter joins Saturn over the sunrise, the pair will continue to rise together, getting a tiny bit farther from the sun each day.

However, in about a month, after Jupiter has risen a little ways above the sunrise, something dramatic will happen to it. On May 17, the waning crescent moon will “hit” Jupiter in the sky! Or rather, it will pass in front of Jupiter and block it from view. It will be a little like a solar eclipse, but instead of blocking out the sun, the moon will block our view of Jupiter. We call this a “lunar occultation,” and like a solar eclipse it will only be visible to a small portion of the world. However, this one favors North America. In a nutshell, viewers in eastern North America should be able to go outdoors before sunrise on the 17th, and watch the crescent moon approach and pass across Jupiter over the course of an hour or so. Timing will be important here. If you go out too early, the moon will not have risen yet. If you go out too late, dawn will be too bright and you won't be able to see Jupiter. And if you live too far to the west, your “window of opportunity” will be closed completely. Roughly speaking, if you live west of the Mississippi, the event won't even begin until after the sun rises. For more details, the International Occultation Timing Association has a website full of technical details, and Dominic Ford has a somewhat more user-friendly page describing the event.

That's all. Thanks for reading, and here's to beautiful skies!

John