Weekly Sky Report
The Griffith Observatory Sky Report
This is the Griffith Observatory Sky Report through April 9th, 2020. Here’s what’s happening in the skies of southern California.
The planet Venus is now nearing the highest and brightest part of its evening appearance this year. This week, Venus moves from below to well above the Pleiades star cluster and this should provide a spectacle through binoculars. On April 3, the planet will cross the bottom edge of the cluster, very nearly repeating the position it occupies every 8 years on about the same date. This cycle results from the fact that 8 Earth years is the same, to within a few hours, as 13 Venus years.
Remember that Venus, from an astronomical perspective, is just a foreground object in our solar system passing in front of an interesting feature in the background provided by more distant parts of the Milky Way galaxy. Venus is currently about 59 million miles away from us, the distance that a beam of light crosses in about five minutes. For comparison, the stars of the Pleiades are 444 light-years away, the distance that light travels in 444 years, or about 2,600 trillion miles! As you look at the Pleiades, remember that the brightest star of the group, Alcyone, is actually about 1,000 times brighter than the sun. Imagine how faint the sun would look from that distance!
Venus is currently on the side of its orbit that is closer to the Earth than the sun. Therefore, less than half of Venus’s daytime side is turned toward us producing a crescent phase that may be seen through any telescope capable of 15 power or more. In coming weeks it will eventually become possible to see Venus as a crescent through binoculars as the distance between the Venus and Earth continues to decrease through early June.
Bright moonlight is present throughout most of the nighttime hours this week. The moon’s phase changes from waxing gibbous to full on the night of the 7th, at 7:35 p.m. On following nights, it is waning gibbous as it heads for last quarter phase on the 14th.
The beautiful grouping of the bright outer planets Mars, Jupiter, and Saturn, continues to beckon at dawn. The planets are the brightest objects after the moon in the sky at that time. They are located above the southeast horizon, and to the left of the bright constellations Scorpius the Scorpion and Sagittarius the Archer. In order, ascending from left to right, they are Mars, Saturn, and Jupiter. Look at about 5:45 a.m.
Jupiter’s four largest moons, its Galilean satellites, may be visible through binoculars if they are held steadily. Saturn’s rings require a telescope capable of 20 power or more in order to be observed. Mars is still a long way from its relatively close swing by the Earth in autumn, but it is close enough for some details to be spotted through telescopes of high optical quality that are more than four inches in diameter and high magnification.
The International Space Station passes directly over Los Angeles on Tuesday evening, the 7th, and it then is expected to rival Venus in brilliance. The ISS will cross the sky from northwest to southeast between 7:51 and 7:58 p.m., PDT. The space station will appear directly overhead, when it is 255 miles away, at 7:55 p.m.
In the best interest of our visitors, and to do its duty to help limit the possible spread of the COVID-19 coronavirus, Griffith Observatory is closed until further notice. As a consequence, all public telescopes are closed, and all public events have been cancelled. Please check the Griffith Observatory homepage for current information and continued updates.
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From Griffith Observatory, I’m Anthony Cook, and I can be reached at email@example.com.