Jupiter/Saturn Conjunction 2020

We are in for a treat this year with a planetary conjunction of our Solar System's two largest planets--Jupiter and Saturn.  This is an event that occurs on average every 19.6 years.  Due to the tilt of the orbital planes of the two planets they may seem to go above or below each other.  This year Jupiter will appear just south of Saturn.  The minimum distance separating them will be approximately 6 arcminutes.  The Full Moon is about 30 arcminutes so the separation between the two planets will be about 1/5 the diameter of a Full Moon.

If you look to the southwestern sky after sunset you will see Jupiter and Saturn low but visible to the unaided eye.  Jupiter is more southerly and westerly than the ringed planet.  Watch each night as they appear to get closer to one another in the sky.  Don't worry: they are separated radially by several hundred million kilometers so they won't bump into each other!

On December 21, at sunset, they will be at their closest separation since 1623.  In 1623 however, they appeared closer to the Sun so it was more difficult to see even with the decade old invention of the telescope.

Jupiter/Saturn Conjunction - December 21, 2020

Don't be concerned if it is cloudy or you forget, they will be very close to each other for several days before and after the 21st.  They will fit into most telescope fields of view for more than a week before and after and the same binocular field for a month before and after!  The fields of view of average astronomy equipment are shown below for December 21.

Jupiter/Saturn Conjunction Fields of View

The conjunction occurs at declination of -20.5° which means it will not be visible to those few hundred thousand people living in the cold northern climes above 69.5°N latitude.  In the south, the Sun is at -23.5°S so those below 66.5°S latitude are experiencing permanent Summer sunlight and will not be able to see the event without specialized equipment.  Anyone close to those latitudes will certainly have a lot of trouble seeing the event.  

However, it will be visible to those with clear skies at any longitude in between these latitudes.  At any given time during the year the Earth faces the same area of the sky and anyone at the same latitude will see the same thing at the same local time.  The sky at 5pm in Calgary will be very similar to 5pm in London, England as they are both approximately 51°N. 

Is this an event that only happens once?  No.  As mentioned above these two planets are in conjunction every 19.6 years.  Sometimes they are closer, sometimes they are further away from each other.  In the 7000s CE they will be so close that Jupiter will eclipse Saturn!  Are planetary conjunctions rare in general?  No.  There will be three conjunctions in January 2021: (Mercury/Jupiter, Mercury/Saturn, Mars/Uranus).

Major and Minor News Outlets have not been completely accurate in their reporting of this event so it is best to ask a local astronomer if you have any questions related to this conjunction or any other event that happens in the night sky.  Misinformation is breeding on social media due to inaccurate reporting so before you share anything please fact check.

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Explore the Moon - Ptolemaeus

 Background

The crater Ptolemaeus is located close to the center of the nearside of the Moon just south of Sinus Medii.  It lies directly south of the crater Herschel.  The crater is named after the famous  astronomer Claudius Ptolemy.  Many books  have been written on Ptolemy's contributions to science and he remains one of the most important astronomers in history.  He was born in Egypt around 100 A.D. and spent his time in Alexandria.  He published the famed "Almagest" which contains a record of ancient historical astronomical models of the sky.  He lists 48 constellations which has been converted into our modern system of delineating regions of the sky.

Herschel (Image Credit: NASA Apollo 16)

Ptolemaeus is a fairly large crater with a diameter of 154km and a depth of 2,400m. 

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	23:56
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

Ptolemaeus is larger than its neighbouring craters Hipparchus and Albategnius.  It appears flooded which would mean it is a fairly old crater.  There is a crater on the northeastern quadrant of the floor visible and named Ammonius.  The southern edge of the rim is broken by neighbouring Alphonsus.

Location

To help you locate this object a map has been provided from the Royal Astronomical Society of Canada's Observer's Handbook.  It is object #75, highlighted below.

Ptolemaeus (Crater)

The image below is a view from the Apollo 12 mission.  The Apollo 12 lunar module, Intrepid, can be seen descending to the lunar surface.  Ammonius is clearly visible in the foreground with Herschel off the the right of the image.

Ptolemaeus (Image Credit: NASA Apollo 12)

Explore the Moon - Herschel

Background

The crater Halley can be found directly south of Hipparchus near the center of the nearside of the Moon.  The crater is named after the English astronomer, Edmond Halley.  Halley is probably most famous for calculated the periodicity of his eponymous comet.  Halley was a contemporary of Isaac Newton and they worked together on the physics of gravity.  Halley even funded the publication of Newton's Magnus Opus, Philsophiae Naturalis Principia Mathematica.  He voyaged to the Southern Hemisphere to map the stars as Flamsteed had mapped the Northern Hemisphere.

Herschel (Image Credit: NASA Apollo 12)

Herschel is a moderately sized crater with a diameter of 41km and a depth of 3,770m. 

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	23:51
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

Herschel can be found just north of the large crater Ptolemeus.  The crater appears to be fairly deep with ridges visible around the edge.  There is a clear central peak formation.  A valley was observed to the east of the crater.  There are two smaller craters to the southwest and northwest 90° from each other.

Location

To help you locate this object a map has been provided from the Royal Astronomical Society of Canada's Observer's Handbook.  It is object #53, highlighted below.

Herschel (Crater)

The image below is another great view from the Apollo 12 mission.  The crater just above Herschel is known as Herschel C with a diameter of 10km and just below that is Herschel X with a diameter of 3km.

Herschel (Image Credit: NASA Apollo 12)

Explore the Moon - Sinus Medii

Background

Sinus Medii (Bay of the Centre) can be found, as the name suggests, right in the centre of the nearside of the Moon.  Its flooded floor has the origin of the Moon's coordinate system.  It is located south of Mare Vaporum and north of Ptolemaeus.  

Sinus Medii (Image Credit: NASA LRO)

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	23:31
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

I observed Sinus Medii to the southwest of Mare Vaporum.  I noticed immediately what appeared to be lines of mountains in a 'pincer' type pattern with a moderately sized crater (Pallas) at the apex with central peaks.  The pincer mountain formation was located in the northwest edge of Sinus Medii.  On the northern most pincer there was a small crater (Chladni) at the end of the mountain chain.  A slightly larger crater (Triesnecker) was seen just to the east of Chladni.  When the seeing was steady I was able to make out a couple smal craters (Bruce and Blagg) in the southern regions of the bay.

Location

To help you locate this object a map has been provided from the Royal Astronomical Society of Canada's Observer's Handbook.  It is object SM, highlighted below.

Sinus Medii (Bay)

Another great view is from the Apollo 16 mission.  This view below has the southeastern edge in the foreground while viewing across to the northwestern edge.  On the front edge the crater Rhaeticus is visible with a strong ring of mountains around it.  Further to the back on the right side is the 27km diameter Triesnecker.

Sinus Medii (Image Credit: NASA Apollo 16)

Explore the Moon - Mare Vaporum

Background

Mare Vaporum (Sea of Vapor) can be found southeast of the Apennine Mountains of which the other side is Mare Imbrium.  The northeast border is several lunar lakes and Montes Haemus which lies between Mare Vaporum and the much larger Mare Serenitatis (Sea of Serenity).  Directly to the west is Sinus Aestuum (Seething Bay) of which Eratosthenes encroaches upon the northern shores.  Mare Vaporum is a relatively circular sea with a diameter of approximately 230km which approaches the size of some large craters on the nearside.

Mare Vaporum (Image Credit: NASA Apollo 17)

Observation

My abbreviated observation record can be found below:

Date	2020-06-01
Time	23:54
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

I observed Mare Vaporum south of the Apennines which seemed to form a thick border.  A thinner border with Mare Serenitatis was also noticed.  Compared to the Apennines these seemed more like smaller hills.  There was a moderate sized crater (Manlius) between Mare Vaporum and Mare Serenitatis.  There were rilles and hills throughout the middle of the sea along with darker patches of lunar floor.  The south edge of the sea had a noticible gouge (Rima Hyginus) with a crater (Hyginus) in the middle.

Location

To help you locate this object a map has been provided from the Royal Astronomical Society of Canada's Observer's Handbook.  It is object MV, highlighted below.

Mare Vaporum (Sea)

Explore the Moon - Apennine Mountains

Background

The Apennine Mountains (Montes Apenninus) can be found on the southerneastern edge of Mare Imbrium (Sea of Rains).  The 100km wide mountain range extends nearly 1,000km from the crater Eratosthenes running in an arc northeast to a gap between Mare Imbrium and Mare Serenitatis (Sea of Serenity).  The tallest (base to peak) mountain on the Moon, Mons Huygens, is contained within this range and reaches 5,400m into the sky.  The Apennine Mountains formed from the impact event that created Mare Imbrium nearly 4 billion years ago.  It is interesting to note that Apollo 15 landed at the base of Mons Hadley Delta in the northeastern region of this range.

Apennine Mountains (Image Credit: NASA LRO)

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	23:17
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

The Appenine Mountains were found south of the craters Autolycus and Archimedes.  There seemed to be a noticeable foothills region on the northern edge of the main range.  I saw two craters south of the range and later determined them to be Conon and Aratus.  As I looked southwest from Mare Serenitatis the range seemed to get thicker before again thinning out as it approached Eratosthenes.

Location

To help you locate this object a map has been provided from the Royal Astronomical Society of Canada's Observer's Handbook.  It is object F, highlighted below.

Apennine Mountains (Mountain Range)

Another great view is from the Apollo 15 mission.  This images has the moderately sized crater Conon on the far right with the bulk of the Apennines below.  The river-like feature is Rima Hadley which stretches for 80km at 2.5km wide and passes by the crater Hadley C.  The Apollo 15 mission landed just above the top (northeastern) bend of Rima Hadley.

Apennine Mountains (Image Credit: Apollo 15)

Explore the Moon - Mare Frigoris

Background

Mare Frigoris (Sea of Cold) can be found stretching nearly 1,500km across the northern section of the Moon.  It runs east from Mare Serenitatis (Sea of Serenity) all the way west to Sinus Roris (Bay of Dew) just off of Oceanus Procellarum (Ocean of Storms).

Mare Frigoris (Image Credit: NASA LRO)

Observation

My abbreviated observation record can be found below:

Date	2020-06-01
Time	23:54
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

I observed this mare when the terminator was intersecting with the larger portion of Oceanus Procellarum.  In the west it seemed to stretch all the way to just north of Sinus Iridum (Bay of Rainbows) and ended near a crater named Harpalus.  In the east, I followed it to the northern reaches of Mare Serenitatis just past Aristoteles and Eudoxus.  It seemed to empty into Lacus Mortis (Lake of Death).  The Alps Mountains offer a strong border between it and Mare Imbrium (Sea of Rains) on the east side of Plato.  However, on the west side of Plato the border does not seem to contain as much altitude.  This mare is so long it would be good to observe this over eight days starting from a couple days before first quarter.

Location

To help you locate this object a map has been provided from the Royal Astronomical Society of Canada's Observer's Handbook.  It is object MFr, highlighted below.

Mare Frigoris (Sea)

Another great image comes from Lunar Orbiter 4 from 1967.  This shows the mare stretching from Harpalus in the west, north over Plato, past Aristoteles, to end just north of Lacus Mortis.

Mare Frigoris (Image Credit: NASA Lunar Orbiter 4)