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October offers the best celestial treats, including harvest and blue moons

(AP Photo)

With the summer monsoon season on the way out, we come to one of the best months of the entire year for observation of the night sky – October.

October has traditionally been one of the clearest of the months of the year and one that offers up additional stable air to use a telescope at its best.

This new month will offer us some great viewing of the planet Mars, as it reaches its best observing position of all of 2020. More on that later.

We begin with the nearest of all celestial objects, the moon.

October 2020 begins with the first of two full moons, as the first is one of the most famous of all full moons. Welcome the full harvest moon of 2020.

The harvest moon is the first full moon which occurs after the Sept. 22 autumnal equinox.

Historically, the harvest moon is one which rises just before sunset and appears in the skies at an earlier time, so farmers might have more light to harvest crops by.

Normally the full moon rises some 50 minutes later each day, but around this time of the year that shrinks to around 20 minutes, giving us the illusion of a bright moon in the sky near sunset time.

This year, the harvest moon is official at 2:05 p.m. Arizona time, but will not rise for us here until 6:32 p.m., due east at 90 degrees. The sun will set on that date at 6:11 p.m.

This provides us with a spectacular view of the rising Harvest Moon, just 21 minutes after sunset.

Do not miss the rising of this special full moon!

Here is what the harvest moon will look like in a clear sky.

If you miss this one, we get a second full moon on of all nights, Oct. 31 – Halloween!

This will be the rare “blue moon” and the hunter’s moon also.

The “blue moon” is the second full moon in a calendar month by some, or the fourth full moon is a season.

This Halloween full moon fits both categories. The last time that we had a true full moon on Halloween was back in 1944.

If you miss this moon, the next true Halloween “blue moon” will not occur till the year 2039 and then in 2058.
That is, a 100% illuminated moon.

There is a cycle of 19 years, known in astronomy as the Metonic cycle, in which the moon will appear at the same phase on the same date but not always, due to the moon’s orbital period.

More on the definition of the “blue moon” is here.

The moon will move on to its last quarter Oct. 9 and back to the new phase seven days later.

Look low in the southwest sky around Oct. 18 for a new waxing crescent moon. First quarter will occur Oct. 23.

For planets, Mercury makes for a shallow view in the west Oct. 1, as it reaches another elongation of some 26 degrees from the sun.

Looking to the left and to the east, we come to the two giants of the solar system. Jupiter and Saturn lie in the south at sunset and make for an easy view.

The main event for planets in the October sky is Mars!

Mars will reach its closest point to Earth as it comes within 38 million miles of us.

Mars reaches its opposition on the 13th, rising in the east at sunset and in the sky all night.

Mars will not be this close or bright again until 2035, so now is the time to get set with your plans to view the planet in a telescope.

During that moment, Mars will be some 22.3” of arc in size…large enough to se some surface detail in a moderate scope.

Here is what Mars will look like at the time of opposition.

Here are some named features on Mars in a telescope.

A guide to imaging Mars in a telescope.

As we move into the predawn skies of October, we come upon the brilliant planet Venus high in the northeast sky.

On a final note, we get to experience one of the best meteor showers of the year with the annual Orionid meteor shower, peaking on the morning of the 21st.

Look due east after 2 a.m. Arizona time, as the constellation of Orion will be easy to see in a clear and moonless sky.

All meteors from this shower are part of Halley’s Comet.

Here is a finder chart for the Orionid meteor shower.

October will have something for everyone in our Arizona skies.

To print your own monthly star chart, click here.

To view satellites/dates/times of passage, click here.

Listen to the Dr. Sky Show on KTAR News 92.3 FM every Saturday at 3 a.m.

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