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This is the Griffith Observatory Sky Report through May 21st, 2020. Here’s what’s happening in the skies of southern California.
The planet Venus, the brightest object in the sky after the sun and moon, has been spectacular since it first appeared at the start of this year, gleaming high in the western sky after sunset. Now it is about to swing past the sun on its speedy orbital track, between the sun and the Earth, to spend 8 months in the morning sky. As a result of this approaching swing by the sun, Venus is getting noticeably lower in the sky from one evening to the next. If you start to look for it at sunset, when Venus is already bright and easy to see, its elevation in the west-northwest is 25 degrees on the 14th but on the 21st it is only 18 degrees high. During this period, the time that it can be seen after sunset shrinks correspondingly from 2 hours, 20 minutes to 1 hour, 40 minutes. Find it while you can!
As it passes close to us, Venus appears larger than any other planet in the sky. Ordinary binoculars, if they are held steadily, may let you glimpse the slender crescent of Venus.
By Monday the 18th, also be on the lookout for the innermost planet, Mercury. On that evening, at 8:15 p.m., Mercury should appear similar to a bright star, and it can be found between Venus and the western horizon. Night by night through the 21st, Mercury and Venus will appear to draw closer together in the sky until the two planets are separated by only one degree. The planets are then said to be in conjunction. A telescope will show Mercury to appear much smaller than Venus, and it has a gibbous phase. Even though Mercury is closer to the sun than Venus, it is also on the far side of its orbit, beyond the sun from our perspective, so we can see most of Mercury’s daytime half. This gives it a gibbous phase when viewed through a telescope. Now that you now how to find it, keep track of Mercury for the next couple of weeks, and you’ll see it become crescent too, as it also moves to the side of its orbit between us and the sun.
The moon’s phase wanes from last quarter on the 14th to new on the 21st, when it can no longer be seen. It’s rising time advances from 2:30 a.m. to 4:50 a.m. between the 15th and the 20th, when it last appears in the morning sky.
At dawn, the brilliant cream-colored planet Jupiter and the golden-hued planet Saturn gleam in the south as an eye-catching pair, separated from one another by nearly five degrees. They are located to the left of the teapot-shaped pattern of stars that distinguish the constellation Sagittarius the Archer.
The waning crescent moon is below the orange planet Mars, far to the left of Jupiter and Saturn, before dawn on the 15th.
As the moon clears out of the sky at dawn, a brief chance opens up for us to see a comet that has been charming southern hemisphere observers for the last few weeks. The comet, C/2020 F8 SWAN, was discovered earlier this year, brightened quickly, and put on a show with a photogenic long tail earlier this month. Over the last 10 days, however, its brightening has stopped. It did not break up, as did comet C/2019 Y4 ATLAS, another comet that had also showed promise and that we were expecting to possibly put on a good show at this time. To see comet SWAN, you should look between 4:00 and 4:15 a.m. During that time, the fuzzy glow of the comet will appear no more than 4 degrees above the northeast horizon while its position moves north, morning by morning, in a path that is nearly parallel to the horizon through the constellation Perseus the Hero. Comet SWAN is now magnitude 6 which may be very challenging to find, even with binoculars, especially considering its position so low in the sky. It might be interesting, nevertheless, to see or photograph its upward streaming tail, a few degrees long, which may be possible to detect above the horizon at 4:00 a.m. before dawn starts. Observation will require a dark wilderness location with a flat and unobstructed horizon to the northeast. A chart that can help you hunt for the comet is provided on our webpage.
May 14 is the 85th anniversary of the opening of Griffith Observatory. Unfortunately, however, because of measures in place that are intended to reduce the spread of the COVID-19 Corona virus, Griffith Observatory and its grounds remain closed until further notice. Consequently, all public telescopes are closed, and all public events have been cancelled. Please check the Griffith Observatory homepage for current information and continued updates of the situation.
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From Griffith Observatory, I’m Anthony Cook, and I can be reached at my new email address, Anthony.Cook@lacity.org.