A clear sky this morning allowed brilliant Morning Star Venus and bright Mars to put on a planetary display before sunrise.
by Jeffrey L. Hunt
A north breeze that cleared smoke from the western wildfires revealed bright planets and bright stars.
At about 4 a.m. CDT, bright Mars was high in the south-southwest. It is among the dim stars of Pisces. The Red Planet is slowly retrograding – moving westward compared to the starry background. This illusion occurs when our faster moving planet approaches and passes the slower moving outer planets.
Mars is closest to Earth on October 6. As Earth approaches Mars, the Red Planet becomes brighter, but not much larger in appearance to the human eye. While it can double in its apparent size through a telescope, the increase is imperceptible to the human eye (unlike what is shown in the social media memes.)
Earth moves between the sun and Mars on October 13. This is called opposition, because the planets appear on opposite sides of Earth and their place and visible times are opposite of each other.
At opposition, a planet rises at sunset, appears in the south around midnight, and sets in the west as the sun rises in the east. Mars appears at opposition about every 26 months.
On the photo above, Mars appears 1.9° to the upper left of Nu Piscium (ν Psc on the photo) and 2.5° to the lower left of Omicron Piscium (ο Psc).
At this hour, brilliant Venus is low in the east. An hour later, about 90 minutes before sunrise, the planet is higher in the sky.
At this time Venus appears with other bright stars. The night’s brightest star, Sirius, is low in the southeast. About a month ago, the star made its first appearance in the morning sky this year.
The famous constellation Orion – with its bright stars Betelgeuse and Rigel – are to the upper right of the Dog Star.
With a binocular the Orion Nebula, a stellar nursery – is visible as a hazy cloud. The Little Dog Star – Procyon – is nearby. The Gemini Twins – Castor and Pollux appear above Venus
Among the stars Venus is moving eastward in the very dim starfield of Cancer. This morning it is 1.4° to the lower left of Omicron Cancri (ο Cnc on the photo). Watch Venus move farther away from ο Cnc.
Here is a daily summary about the planets during September.
April 25, 2021: Mercury passes Evening Star Venus this evening after sunset. Look low in the western sky about 20 minutes after sunset. Mars is marching eastward in Gemini, near the star cluster Messier 35. The bright moon is near Spica.
April 25, 2021: Morning planets Jupiter and Saturn are in the southeast before sunrise. Jupiter is in front of the stars of Aquarius, while Saturn’s starry background is Capricornus.
April 24, 2021: Brilliant Evening Star Venus and bright Mercury are entering the evening sky. They are low in the west-northwest during evening twilight. The bright moon is in the southeast in Virgo. Mars moves into Gemini as it approaches the star cluster Messier 35.
April 24, 2021: The bright gibbous moon is near a star in Virgo during the early morning. From parts of the Western Hemisphere, the moon covers the star. Before sunrise, bright morning planets, Jupiter and Saturn are in the southeast before sunrise.
April 23, 2021: Evening Star Venus and Mercury are entering the evening sky. They are found very low in the west-northwest after sunset. The bright moon is in the southeastern sky during the early evening. Mars is moving toward the star cluster Messier 35.