The Great Conjunction of 2020

On December 21, 2020 Jupiter and Saturn will appear closer in our sky than they have since the year 1623 — only .10º apart. By way of comparison, Earth’s Moon covers about .50º on average! In fact, the two planets will have so little visual separation that they may appear as one bright “star” in our evening sky. As with many objects we see in our night sky, planets Jupiter and Saturn will only appear to be near to each other; they will will be physically separated by about 456 million miles.

The position of the planets as they will be at 7:00 PM EST, December 21, 2020. The bright green line represents the sight line from Earth to Jupiter and Saturn. Image Credit: SkySafari / James Guilford

Here’s why the planets will appear so close in our sky:

Viewed from Earth and looking out toward Jupiter and Saturn we see the planets as if they were in the same orbit — like watching runners in their separate lanes as one overtakes the other. Viewed from “above” we can see that the planets remain well apart.

Viewed closer to the orbital plane of the planets we see how Jupiter and Saturn appear closer together against the background of space. The green line represents the sight line from Earth to the planets. Image Credit: SkySafari / James Guilford

As we drop lower and closer to the orbital plane it becomes more difficult to separate Jupiter and Saturn until, on December 21, 2020, we won’t be able to see them as discrete objects without the use of a telescope!

Jupiter and Saturn appear to merge, on December 21, 2020 as viewed from Earth and depicted here just above the orbital plane of the planets. Image Credit: SkySafari / James Guilford

While the previous extremely close conjunction took place in 1623, Jupiter and Saturn were too close to the Sun to be observed. The last time they could actually be seen so close together was even longer ago: on March 4, 1226. Great Conjunctions take place just short of 20 years apart and most are not so close as this year’s — the next will take place on October 31, 2040, when Jupiter and Saturn will be separated by 1.1º which will be close, but not so amazing as 2020.

Jupiter and Saturn may be seen in the same narrow field of view during 2020’s Great Conjunction. This simulation depicts the position of Jupiter’s Galilean Moons and Saturn’s giant satellite, Titan. Image Credit: SkySafari

If you plan to take a look, you’ll need clear skies (of course!) and you’ll need to be timely — the planetary pair will become visible low in the southwestern sky with the fading twilight and will set in the west by 7:20 PM, December 21. To see the individual planets during their close encounter will require a telescope — a small one will do — or a decent telephoto lens on a camera mounted on a tripod. Given good optics and clear skies, viewers will be able to make out the Galilean Moons of Jupiter and, perhaps spy Titan, Saturn’s brightest moon.

Before and after the 21st, Jupiter and Saturn will appear close together as they first approach, and then recede from the conjunction, continuing to move along their orbital paths. The historic astronomical event will be one night and one night only in our lifetimes. Clear skies, please!

Weak lunar eclipse coming November 30

There will be a lunar eclipse the morning of November 30, 2020 but you may not want to get out of a warm bed to view it — it will be fairly “weak.” This month’s eclipse, viewable in its entirely from Northern Ohio (given clear skies) is of the penumbral variety and will not display the eerie colors that make total lunar eclipses so exciting.

NASA Solar and Earth images, illustration by James Guilford.
A penumbral lunar eclipse occurs when the Moon passes through the thin outer portion of the shadow Earth casts out into space.

A penumbral lunar eclipse occurs when the Full Moon passes through the shady outer circle — the penumbra — of Earth’s shadow streaming out into space. Careful observers will note how most of Moon dims slightly with a sliver of a brighter southern edge and a darker northern area. During a total lunar eclipse, the Full Moon passes fully through the darkest portion of Earth’s shadow, the umbra, and is illuminated by the colors of the globe’s sunrises and sunsets. Again, that won’t happen this time.

Penumbral Lunar Eclipse – November 30, 2020. Credit: F. Espenak, NASA’s GSFC

Most of Monday’s event is quite subtle and takes a long time, many won’t even notice the difference. If you want to see this eclipse at its best, even photogenic, view it only around maximum. The penumbral eclipse begins [P1] at 2:32 AM, reaches its Greatest eclipse (you may note northern darkening) at 4:52 AM, and the event ends [P4] at 6:53 AM when Moon completes its emergence from Earth’s shade.

The next total lunar eclipse — the type that features coppery-red colors at its peak — will take place May 26, 2021; unfortunately, that event will reach its maximum as Moon sets locally. The next total lunar eclipse that we might see in its entirety will take place May 16, 2022 and that should be a doozie!

October 12 monthly meeting takes place via Zoom

Because our regular meeting place is closed in accordance with COVID-19 restrictions, meetings of the Cuyahoga Astronomical Association (CAA) are taking place via the popular Zoom service.

The title of tonight’s talk is “Our Amazing Moon” presented by our local lunar expert Bill Murmann. He will discuss our nearest neighbor in space and the critical role it plays in our lives, and the possible role it may play in our future.

Here is how to attend the October 12 meeting via Zoom when “doors open” t 7:20 p.m. —

Either “Phone in” or watch and participate via “Zoom Video”.

Phone In: Just dial: 1-312-626-6799 (Chicago number)

You will be required to enter our Meeting Number: 987 496 1637


Zoom Video with video and audio, on your web browser. (No camera required) (No password to enter)

If you are tech-savvy, go to, you can download and install their app on your phone, tablet, or computer, then join our meeting using the Meeting Number given above.

Meeting Agenda

7:20 Meeting will be opened to everyone. (Socializing is welcomed!)

7:30 Opening Announcement will be made (All will be muted)

Introduction of President for commentary

Vice President will introduce our speaker for the evening

Speaker will ‘take the floor’. (No questions during the presentation)

Question & Answer session (Please be patient, it does take time to manipulate)

8:20 (ish) President calls the CAA Business Meeting to Order (All Muted)

At conclusion of the meeting, everyone is welcome to stay to socialize.

Penumbral Lunar Eclipse: July 4 – 5

NASA Solar and Earth images, illustration by James Guilford.
A penumbral lunar eclipse occurs when the Moon passes through the thin outer portion of the shadow Earth casts out into space.

We’re fortunate that the night of July 4 is expected to be clear, and not just for the traditional booms and flashes of celebratory fireworks. Our Moon is getting in on the act, albeit with a much more subtle display in the form of a penumbral eclipse. The eclipse will take place from 11:07 PM to 1:52 AM EDT with maximum eclipse at 12:31 AM July 5.

We say subtle because, unlike a total lunar eclipse, Earth’s Moon will not change to reddish/coppery colors. The Moon will instead become oddly shadowed for a Full Moon, as it enters the outer fringes of Earth’s shadow in space — the penumbra. Only the “top” portion of Luna will pass through the penumbra making this eclipse especially slight. Still, it’s worth a look and it won’t be at a particularly late hour. A deeper penumbral lunar eclipse will take place the night of November 30, 2020.

Moon is eclipsed when it passes through Earth's shadow. Credit: SkySafari / J. Guilford
Earth’s shadow runs away from the Sun into space and has two parts: the deep inner shadow or umbra, and the thin outer portion called the penumbra. The Moon is eclipsed when it passes through Earth’s shadow. Credit: SkySafari / J. Guilford

While it’s possible to view this eclipse with the unaided eye, binoculars will provide an enhanced view as would a small telescope.

Penumbral Lunar Eclipse of July 4 – 5, 2020 at Maximum Eclipse: 12:31 AM EDT. Simulation via SkySafari

And just in case there’s any confusion, lunar eclipses are perfectly safe to view and photograph — it’s moonlight — so nothing to worry about there.

If you shoot any photos or have impressions to share with us, you can do so via our Twitter — @Cuyastro

Penumbral Lunar Eclipse of July 4 – 5, 2020. Credit: NASA

NASA Eclipse Page available here: Penumbral Lunar Eclipse of July 4 – 5, 2020.