Fall’s here! As the cold evenings begin to return in the north and the days start getting longer than nights, the night sky is in transition too. It’s time to welcome the winter constellations like Orion, Taurus, Gemini, and the meteor showers with a radiant point in those constellations. October 2021 is going to be a busy month for astronomy enthusiasts. Here are some of the must-watch astronomical events in October 2021. The planet round-up of the month is given at the end of the article.
Astronomical events in October 2021
October 2: Andromeda at culmination
The Andromeda galaxy will reach its highest point in the night sky and can be seen with naked eyes. Andromeda is the biggest galaxy of the local group. It’s one of the nearest spiral galaxies to the Milky Way. It lies in the constellation that goes by its name, Andromeda. The apparent magnitude of Andromeda will be +3.4, which means you can spot it with unaided eyes under perfectly dark skies away from city lights. At a declination of 41°16’N, it is easiest to see from the northern hemisphere but cannot be seen from latitudes much south of 28°S.
Andromeda will rise around sunset, reach its highest point in the sky at midnight, and set at dawn. You can quickly use these space apps to locate the galaxy and other celestial objects according to your location.
October 5: Camelopardalid meteor shower
The October 2020 Camelopardalid meteor shower will be active from 5 October to 6 October, producing its peak meteors around 5 October. From much of the Northern Hemisphere, the radiant (the point in the sky from where all the streaks appear to originate) of this shower is circumpolar, which means the shower will be active throughout the night. The Moon, ending its cycle, won’t cause any interference.
October 6: New Moon
The Moon will pass close to the Sun and be hidden in its glare for a couple of days. It’s a great chance to see faint celestial objects such as star clusters, galaxies, and nebulae that are otherwise washed away by the moonlight.
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October 8: Draconid meteor shower
The second of the seven meteor showers in October 2020, the Draconid meteor shower, will be active from 6 October to 10 October, producing its peak rate of meteors around the 8th. The radiant of the shower lies in the constellation of Draco. The Moon will appear soon after the sunset, and hence, it won’t cause much interference. The shower will be active from dusk up to a couple of hours after midnight.
October 8: Mars at Solar Conjunction
Mars’ orbit will take the planet to the opposite side of the solar system with respect to the Earth. A year ago, around this date, Mars used to dominate the night sky with its blazing red hue. However, the planet is now hidden in the Sun’s glare and will remain so for the coming few weeks.
October 10: Southern Taurid meteor shower
The Southern Taurid meteor shower is active from 10 September to 20 November, producing its peak meteors around 10 October 2021. At its peak, the shower is expected to produce up to 5 meteors per hour. The radiant of this shower lies in Cetus. Southern Taurids will produce their displays about an hour after midnight, and hence, the 4-day-old Moon won’t be up in the sky to wash away the faint meteors.
October 11: Saturn ends retrograde motion
Saturn will end its westward motion through the constellations and resume its usual eastward motion in the sky. The retrograde motion of the superior planets (planets beyond Earth) occurs due to Earth’s motion around the Sun. As the Earth circles the Sun, our perspective changes, and this cause the apparent positions of objects to move from side to side in the sky with a one-year period. This nodding motion is superimposed on the planet’s long-term eastward motion through the constellations. The phenomenon has been illustrated below:
October 14-15: Moon, Jupiter, and Saturn
The Moon will pass close to Saturn and Jupiter on October 14 and 15, respectively. The trio will become visible as soon as the dusk sky fades. The brighter of the two planets will be Jupiter.
October 18: Jupiter ends retrograde motion
After Saturn, Jupiter will end its westward motion through the constellations and resume its usual eastward motion in the sky.
October 20: Full Moon
The Moon will reach its full phase on October 20 and lie opposite the Sun.
October 21: Orionid meteor shower
The best meteor shower of October is the Orionid meteor shower, active from 2 October to 7 November, producing its peak rate of meteors around 21 October 2021. The radiant of this shower lies in the constellation of Orion, as shown below:
At its peak, the shower is expected to produce a nominal rate of around 15 meteors per hour. You don’t need any telescope to relish the meteor shower. Just find a dark place away from light pollution and give your eyes at least 30 minutes to adapt to the darkness. You may use these space apps to locate the shower’s radiant easily.
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October 24: Moon at Perigee
The Moon will reach its farthest point from the Earth and will appear slightly smaller than usual.
October 26: Mercury at highest point in the morning sky
Mercury will reach its highest altitude in the sky in its Oct–Nov 2021 morning apparition. It will be shining brightly at mag -0.6 in Virgo. The planet can be easily seen as it will be well separated from the Sun, rising at a peak altitude of 18 degrees above the horizon.
October 2021 – Planet Round-Up
Mercury will remain hidden in the Sun’s glare in the first few days of October 2021. The planet will become visible in the dawn sky as the month progresses, reaching its peak altitude on the 26th day of the month.
Venus dominates the evening sky after sunset. It’s the brightest speck of light in the sky at an apparent magnitude of -4.5. Venus will be at its dichotomy on 28 October 2021. This means the planet will be half-lit (reach its half phase) as seen from the Earth.
The Red Planet will remain hidden in the Sun’s glare this month. It will pass its solar conjunction on October 8.
Jupiter is the brightest speck of light in the sky after Venus sets soon after dusk. Venus becomes accessible as soon as the evening twilight fades to darkness. Look for the planet in the south-west. It is visible throughout the night, setting in the south-west around dawn.
The bright speck of light shining alongside Jupiter is Saturn. The two gas giants were at opposition in August and hence they continue to dominate the night sky of October 2021.
the seventh planet of the solar system will be at opposition on November 5. This means Uranus is well up in the sky around midnight. At an apparent magnitude of +5.84, it is almost impossible to see the planet with naked eyes.
Neptune passed its opposition in September and hence, the planet rises in the east around sunset, reaches its highest point in the sky around midnight, and sets in the west at dawn. The planet lies in Aquarius and you’ll need a telescope to see it.
Admin and Founder of ‘The Secrets Of The Universe’ and former intern at Indian Institute of Astrophysics, Bangalore, I am a science student pursuing a Master’s in Physics from India. I love to study and write about Stellar Astrophysics, Relativity & Quantum Mechanics.