糖心原创

Tickets for the April 9 showing of 鈥泪苍肠辞尘颈苍驳!鈥� and the April 23 showing of 鈥沦耻辫别谤惫辞濒肠补苍辞别蝉鈥� (the last show of the spring season of shows) at the William M Thomas Planetarium are still available through the .

Last Wednesday, April 1 was a . That was the first full moon after the , which this year was on March 20. Therefore, we鈥檇 expect that tomorrow, April 5, the first Sunday after that April 1 full moon should be Easter and this year, that expectation works out. This rule of thumb doesn鈥檛 always work out though, since . The Paschal Full Moon is the 14th day of the lunar month that occurs on or after March 21 and that lunar month cycle is set according to tables dating back to 325 A.D. that closely approximate the actual motions of the moon. Usually, the approximations match the astronomical facts but not always. Rather than diving further into the rabbit hole of in order to understand all of the nuances of the differences between the two, I leave it to my calendar to tell me when Easter is going to be for that year. 

As I write this, the launch of the first humans to experience all of the phases of the moon up close in a short time is still a future event. The earliest launch opportunity for the carrying a crew of four astronauts around the moon is (was) Wednesday, April 1. The launch window will be open until April 6. The crew will spend one day orbiting Earth as they check out the key life support, communication, and navigation systems. If everything checks out, they鈥檒l fire the rocket for a trans-lunar trek to the moon that鈥檒l take almost four days. They will loop around the moon, getting up to 4600 miles beyond the moon. As they loop around the moon, the amount of the lit side the astronauts will see will constantly change, so they鈥檒l see the moon go through a full sequence of phases in just a few days. They鈥檒l also be the first humans to see the far side of the moon since the 1972 鈥攆ifty four years ago!

The path they鈥檒l take will have them on a four-day free-return trajectory (no fuel needed, letting Earth鈥檚 gravity bring them back). They鈥檒l splash down 50 nautical miles (57.5 statute miles) off the coast of San Diego after traveling more than 595,000 nautical miles during their ten-day mission. For more details of the mission, including hour-by-hour timeline, see the  .

Tonight the will be among the dim stars of Libra. Tomorrow night, April 5, it will be to the right of at the heart of Scorpius. Last (or third) quarter phase will be the night of April 9/10 and the moon will be at the handle of the Teapot part of Sagittarius. New moon starts the phase cycle over again on April 17. 

The two brightest planets, Venus and Jupiter, are visible in the evening sky, shining brighter than any other star in the night sky. Venus blazes away low in the west after sunset among the stars of Aries and Cetus. Jupiter will be high up in the south almost at the zenith on the left side of Gemini. The other three naked eye planets, Mercury, Mars, and Saturn rise shortly before sunrise in the east with Mercury leading the way, followed by Mars, and then Saturn. However, all three will be too close to the sun to see them. Well, possibly Mercury might just be barely visible in the pre-dawn twilight low in the east. 

In the pre-dawn morning of April 15, shortly before sunrise, look east to see a very thin waning crescent moon, Mercury, Mars, and Saturn all clustered closely together (see the inset of the star chart above). Your will be able to totally cover them up. Saturn will probably be too low to see it but the other three should be possible to see, especially if you use binoculars to draw them out from the dawn twilight. On the evening of April 18, the moon will have moved to the left of the sun to be a thin waxing crescent next to Venus in the evening sky.

I hope you鈥檒l make it to one of the April shows at the Planetarium!

鈥�

Director of the William M Thomas Planetarium at 糖心原创

Author of the award-winning website