Tomorrow before dawn – November 29, 2015 – it’ll be hard to miss the planets Venus and Jupiter blazing away in the sky before sunrise. Venus and Jupiter rank as the third-brightest and fourth-brightest celestial bodies, respectively, after the sun and moon. In the predawn hours, you can also catch Spica, the constellation Virgo’s brightest star, near Venus. After you spot Venus and Spica, think of this. For the rest of your life – every 8 Earth-years (every 13 Venus-years) – Venus and Spica will meet up in this same place in the morning sky. So that’s 2015, 2023, 2031, 2039 and so on.
What’s more, Venus will reach perihelion – its closest point to the sun in its orbit – on November 29, 2015. Venus’ orbit is the closest to being circular of all the planets in our solar system. Its distance from the sun only varies by only about 1.5% between perihelion and aphelion (farthest point from the sun).
Venus is well known for its 8-year cycles. This planet – which orbits the sun one step inward from Earth – swings to perihelion 13 times every 8 years. So Venus’ 13th return to perihelion will happen some 8 years from now – on November 28, 2023 – with Venus and Spica returning to virtually the same spot in the November 2023 morning sky.
Venus returns to perihelion 13 times in 8 years:
1. 2016 July 10
2. 2017 Feb 20
3. 2017 Oct 3
4. 2018 May 16
5. 2018 Dec 26
6. 2019 Aug 8
7. 2020 Mar 20
8. 2020 Oct 30
9. 2021 Jun 12
10. 2022 Jan 23
11. 2022 Sep 4
12. 2023 Apr 17
13. 2023 Nov 28
Yet Spica pales next to dazzling Venus, which outshines this star by a hundredfold.
You can reliably count on brighter Venus to guide your eye to fainter Spica throughout late November and early December, 2015. When Venus is no longer there for guidance, you can always star-hop to Spica from the constellation Corvus the Crow.
By the way, you can also spot the red planet Mars between Venus and Jupiter, as shown on the chart at the top of this post. The green line on the chart depicts the ecliptic – Earth’s orbital plane projected onto the dome of sky – and thus the sun’s apparent yearly path through the constellations of the Zodiac.
Because the planets of our solar system orbit the sun on nearly the same plane as Earth, you know you can always look for planets on or near the ecliptic, or the sun’s annual path in front of the backdrop stars.
Bottom line: Watch for the brilliant planet Venus near the bright star Spica in late November and early December, 2015.