Planets in October 2021

Planets in October 2021

This months fun fact about the planets:

Did you know? Wind speeds on Neptune are among the fastest recorded in the Solar System. Some may reach up to 2,160 km per hour.  They are five times stronger than the strongest winds on Earth. The winds on Saturn are the second-fastest.

Mercury

  • Begins the month slightly to the south of the bright star Spica in the western evening twilight. Spica is the brightest star in the constellation of Virgo. It then quickly descends toward the Sun and inferior conjunction when it will be between the Earth and the Sun the 10th making it impossible for us to see until it returns to the early morning sky when it will be hard to spot just above the eastern horizon on the 25th before sunrise.

Venus

  • Shining brilliantly in the western evening sky and you certainly can’t miss it.  Venus will be in the constellation of Libra for the first week of October before moving into Scorpius and finally into Ophiuchus. On the 9th and 10th, it will very close to the Delta (δ) Scorpii which is the middle star of the three-star line that makes up the claw region of the Scorpion. A nice colour contrast will be seen on the 16th and 17th when Venus appears very close to Antares (Alpha (α) Scorpii). Antares is the brightest star of the constellation and distinctly reddish and is known as the heart of the Scorpion.
Figure 2: Venus and Antares looking west on 15 October at 8.34pm AEDT

Mars

  • Mars is in conjunction with the Sun on the 8th and will not be visible until its reappearance in the morning sky during late November in Libra.

Jupiter

  • Jupiter is in a perfect position for observing this month, appearing high in the early north-western evening sky. On the 15th, the 10-day old waxing gibbous Moon pretty close to Jupiter (see Figure 3). Jupiter has been in Capricorn since August now on the 18th it will appear stationary as it comes to the end of four months of retrograde motion. It will then  resume its west to east motion across the sky and head back towards Aquarius.
Figure 3: Jupiter, Saturn and the Moon on 15 October

Saturn

  • Ideally located in the early north-western evening sky for observing. It will appear stationary on the 11th as it comes to the end of its west to east motion across the sky. On the 30th the planet is at a point in its orbit known as eastern quadrature. This is where the Sun-Earth -Saturn angle is 90°. At this time as the Sun sets in the west Saturn will be at its highest altitude in the sky. It is also a favourable time to view the maximum shadow of the planet’s globe cast onto the rings giving Saturn a 3-D appearance. On the 14th, the 9-day old waxing gibbous Moon appears around 4° from the planet.

Uranus

  • With opposition early in November, Uranus rises in the eastern sky soon after sunset, situated in a barren part of Aries the Ram, near the head region of Cetus the sea monster or near the tail of Cetus the whale.

Neptune

  • Now past opposition, Neptune transits the meridian (is due north) around 10PM mid-month Aquarius.
Figure 4: The planets can be categorised into three groups – the gas giants; the ice giants; and the terrestrial planets
Figure 5: Morning sky on 25 October at 2.25am AEDT

Donna the Astronomer

I am a keen astronomer lucky enough to live and work in Coonabarabran the Astronomy Capital of Australia! I am a ‘Drover’s Brat’ and discoverer of a couple of comets and asteroids. I operate Milroy Observatory and can show you how to best integrate dark sky experiences into your tourism, farm stay or AirBnB business.

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