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)

Explore the Moon - Halley

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.

Halley (Image Credit: NASA Apollo 16)

Halley is a moderately sized crater with a diameter of 36km and a depth of 2,510m. 

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	23:40
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

Halley is the largest of four successively smaller craters to the south of Hipparchus.  The edge of Halley actually intersects with the walled rim of Hipparchus.  I noticed a small peak within Halley that was difficult to see.

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 #51, highlighted below.

Halley (Crater)

Another great view is from the Apollo 16 mission.  This image shows Halley right below Hipparchus, neighboured to the east by the crater known as Hind.  The smaller crater further to the east is Hipparchus C.  In the bottom left hand corner is the flooded northeast region of Albategnius.  The sizes of Halley, Hind and Hipparchus C are respectively 36km, 30km, 17km.

Halley (Image Credit: NASA Apollo 16)

Explore the Moon - Alps Mountains

Background

The Alps Mountains (Montes Alpes) can be found on the northern edge of Mare Imbrium (Sea of Rains).  It is a mountain range that is approximately 50km wide and stretches for more than 250km.  The tallest peaks of the Alps reach nearly 2.5km and cast long shadows on the lunar surface.   

Alps Mountains (Image Credit: NASA LRO)

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	22:23
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

The Alps (Montes Alpes) seem to get narrower in the southeastern region after the Alpine Valley bisects it.  This region seemed to have tall mountains as I counted 9 very spiky shadows of peaks.  The range stretched all the way from Plato in the north to Cassini further to the southeast.  There is a slight gap between the Alps and the Caucasus.  I did not notice very many small craters throughout the range except on the western lowlands as it transitioned to Mare Imbrium.

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 B, highlighted below.

Alps Mountains (Mountain Range)

Explore the Moon - Albategnius

Background

The crater Albategnius can be found on directly south of Hipparchus just east of the lunar prime meridian.  It is named after the Arab astronomer, Al-Battani.  Born during the 9th century CE in what is now modern day Turkey, he spent most of his life in Raqqa, Syria.  He improved on Ptolemy's calculations from more than half a millennium ago and determined the length of the year to within 2 minutes of the currently accepted value.  Many famous astronomers, including Copernicus, referred to his work throughout the Renaissance.  Astronomy throughout the Arab world had a golden age throughout medieval times and contributed significantly to our understanding today.

Albategnius (Image Credit: NASA Lunar Orbiter 4)

Albategnius is a large crater with a diameter of 136km and a depth of 4,400m.  

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	23:46
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

Albategnius seemed to have a strong ridge on the eastern edge that may have been higher than the other side.  There were craters noticeable within with a larger crater that breaks the rim on the southwestern edge.  This crater (Klein) had a central peak.  Albategnius itself had a central peak formation that was clearly visible.  The presence of interior craters and a flooded floor indicated to me it was fairly old.

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 #21, highlighted below.

Albategnius (Crater)

Another great view is from the Apollo 16 mission.  This is looking southward with the interior craters Albategnius B and C at the bottom and the larger Klein just off to the right of the central peak formation. The formation know as Alpha Albategnius is nearly 20km long and attains a maximum height of 1,500m.

Albategnius (Image Credit: NASA Apollo 16)

Explore the Moon - Hipparchus

Background

The crater Hipparchus can be found near the center of the Moon on the nearside.  To its immediate south is the large crater Albategnius and to the southwest is Ptolaemeus.  The nearest basin is Sinus Medii (Central Bay) to the northwest which forms the origin of the Moon's coordinate system.  The crater is named after the famous Greek astronomer, Hipparchus.  Hipparchus was arguably one of the most important astronomers in antiquity and worked throughout the 1st Century BCE.  He invented trigonometry, calculated the Earth's precession, invented the astrolabe and compiled one of the first comprehensive star catalogs. Armed with his knowledge, he may have been one of the first astronomers to calculate the recurrence of eclipses.

Hipparchus (Image Credit: NASA LRO)

Hipparchus is a large crater with a diameter of 151km and a depth of 3,300m.  

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	23:33
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

The first thing I noticed about Hipparchus was that it was missing a semicircular section of its southwestern rim.  Also, just outside of its southeastern rim was four successively smaller craters running from west to east.  Hipparchus is noticeably flooded with a very low rim that is partially eroded.  The crater contains several other craters within.  I would speculate Hipparchus is very old.  The ill-formed Hipparchus X was seen just northeast of the missing semicircular rim and was noticeably eroded.  Horrocks in the northeast was prominent and found within the walls of Hipparchus.

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 #55, highlighted below.

Hipparchus (Crater)

Another great view is from the Apollo 16 mission.  This is looking northward from Halley (in the foreground) with Sinus Medii in the background at the top left.

Hipparchus (Image Credit: NASA Apollo 16)

Explore the Moon - Autolycus

Background

The crater Autolycus can be found on the eastern edge of Mare Imbrium (Sea of Rains) just south of the larger crater Aristillus.  It is named after the Greek astronomer Autolycus of Pitane who published books on mathematics and geometry.  His book, On the Moving Sphere may be the earliest completely preserved mathematical book from Greek history.  In his other great work, On Risings and Settings, he remarks "any star which rises and sets always rises and sets at the same point in the horizon".  As a contempoary of Aristotle, Autolycus was a supporter of homocentric spheres, a mathematical model to upload the geocentric conception of the solar system.

Autolycus (Image Credit: NASA Lunar Orbiter 4)

Autolycus is a moderate sized crater with a diameter of 40km and a depth of 3,440m.  The floor is not flooded and the walls show little sign of erosion.  This would make the crater relatively young.

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	23:11
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

I noted that this crater was found in the eastern region of Mare Imbrium between Aristillus and the Apennine Mountains (Montes Apennines).  To its immediate west was the large crater Archimedes.  There were small mountains just south of Autolycus that lead to the larger Apennines.  There was a ridge on the westernmost interior of the crater that indicates a strong terracing slope back to the lunar surface.  Luna 2 landed just to the west of Autolycus just north of some hilly terrain.

Autolycus Sketch

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 #31, highlighted below.

Autolycus (Crater)

Another great view is from the Apollo 15 mission.  This is looking northward from Autolycus to Aristillus.  In the upper right you can see the low formation of Cassini.  The Mountain in the top left centre is Mons Piton and the Alps Mountains are further back.

Autolycus (Image Credit: NASA Apollo 15)

Explore the Moon - Caucasus Mountains

Background

The Caucasus Mountains (Montes Caucasus) can be found on the eastern edge of Mare Imbrium (Sea of Rains).  It is a mountain range that is approximately 100km wide and stretches for more than 520km.  The tallest peaks of the Caucasus reach up to 3650m and cast long shadows on the lunar surface.  The mountain range is just east of Cassini, Aristillus and Autolycus and they stretch all the way to the large craters, Eudoxus and Aristoteles in Mare Frigoris (Sea of Cold).

Caucasus Mountains (Image Credit: NASA LRO)

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	22:57
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

The south end of the Caucasus Mountains seems to have a lone mountain, followed by the much larger range to the north.  An odd shaped crater (almost resembling a square) was seen on the eastern edge of the mountain range.  Another crater of similar size was seen over the mountains just southeast of Cassini.  The Alps and Apennine Mountain ranges seemed to both point to the Caucasus.  The Caucasus stretched all the way north to the large craters Eudoxus and Aristoteles.

Caucasus Mountains

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 H, highlighted below.

Caucasus Mountains (Mountain Range)

Another great view is from the Apollo 15 mission.  This is looking northward from the southernmost point of the Caucasus Mountains.

Caucasus Mountains (Image Credit: NASA Apollo 15)

Explore the Moon - Alpine Valley

Background

The Alpine Valley (Vallis Alpes) can be found on the northeastern edge of Mare Imbrium (Sea of Rains).  It is a narrow (10km) valley that extends for more than 150km between Mare Imbrium and Mare Frigoris (Sea of Cold).  The valley has a rille (Narrow Channel) running through the middle of it.  It is quite difficult to see through a telescope but, with high enough magnification and a steady atmosphere, it is possible.  The Alpine Valley may have been formed when tensional forces caused part of the Moon's crust to sink lower than adjacent regions of crust along parallel fault lines.

Alpine Valley (Image Credit: NASA)

The Alpine Valley stretches 166km at a maximum width of 10km.  The narrow rille contouring throughout the valley stretches 197km and has a maximum depth of 78m and a width being a mere 0.5km.

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	22:23
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

The Alps (Montes Alpes) seem to get narrower in the southeastern region after the Alpine Valley bisects it.  I noted a bright ejecta pattern directly south of the valley which may have been caused when the crater Cassini K was made.  The seeing was not too bad (3/5) but I was unable to resolve the rille within the valley.  I would opine that only the steadiest of skies would allow observation of this feature.  I was, however, able to discern the flooded floor of the valley which indicates it is quite an old structure.

Alpine Valley Sketch

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 A, highlighted below.

Alpine Valley (Valley)

Explore the Moon - Aristillus

Background

The crater Aristillus can be found on the eastern edge of Mare Imbrium (Sea of Rains).  It is named after the Greek astronomer Aristyllus who was one of the first astronomers to create a fixed star catalog.  He was an astronomer at the school of Alexandria in Egypt.  His eponymous crater on the Moon is at a similar lunar latitude as the terrestrial latitude of Alexandria on Earth.  His work was completed during the 3rd Century BCE and was later used by Ptolemy and Hipparchus a century later.

Aristillus (Image Credit: NASA LRO)

Aristillus is a moderate sized crater with a diameter of 55km and a depth of 3,600m.  There is a formation of central peaks within the crater that rise to 900m. 

Observation

My abbreviated observation record can be found below:

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

Comments

I noted that this crater was found between the Caucasus (Montes Caucasus) and the large crater Archimedes.  As I examined the walls of the crater they seemed relatively high and had a terraced structure to them.  Aristillus was approximately the same size as Cassini except it did not have a flooded floor.  This indicates it is younger than its flooded neighbour.  There was a protuberance at approximately 4:00 that may have been small highlands.  Rilles (Narrow Channels) were noticed extending from the north edge of the crater to Mons Piton.  Another rille was seen extending from 2:00 towards the southwest.  A central peak formation was clearly visible.  A smaller crater (Aristillus B) can be found to the northwest

Aristillus Sketch

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 #26, highlighted below.

Aristillus (Crater)

Explore the Moon - Cassini

Background

The crater Cassini can be found on the eastern edge of Mare Imbrium (Sea of Rains).  It is named after the famous Italian/French astronomers Giovanni Cassini and Jacques Cassini.  Giovanni discovered four Moons of Saturn and also noticed the division in the rings.  The Cassini Spacecraft (1997-2017) was also named after him.  His son, Jacques, followed in his father's footsteps and made many contributions to the field of astronomy and cartography.

Cassini (Image Credit: NASA LRO)

Cassini is a moderate sized crater with a diameter of 57km and a depth of 1,200m.  There are two noticeable craters (Cassini A and Cassini B) found within the walls of the larger crater.

Observation

My abbreviated observation record can be found below:

Date	2020-05-29
Time	22:33
Sky	Clear
Telescope	8" Reflector (1200mm F.L.)
Eyepiece	10mm (2x Barlow)
Magnification	240x

Comments

I noted that the southeastern section of the Lunar Alps (Montes Alpes) points directly to Cassini.  The floor of the crater seemed to be somewhat flooded (smooth surface) with two other craters located within.  This would speak to the age of Cassini and its two enclave craters.  The crater may be close in age to the flooded Mare Imbrium. There was a smaller crater (Cassini M) found on the northwest edge of the border.  A large mountain could also be found just beyond the southeast border of Cassini.

Cassini Sketch

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 #34, highlighted below.

Cassini (Crater)

Explore the Moon

The Royal Astronomical Society of Canada hosts many observing programs for members of all ages.  The Explore the Moon is one such program dedicated to providing an introduction to our nearest celestial neighbour.

From the webpage: Explore the Moon

This observing program bridges the gap between the introductory Explore the Universe observing program and the comprehensive Isabel Williamson Lunar Observing Program.  It is ideal for beginning observers who are just learning about telescopes and binoculars, by provided a hands-on observing experience on an easy object--the Moon.

A link to the observing guides can be found below:

Explore the Moon - Telescope
Explore the Moon - Binocular

Full Moon

There are two types of certificate to earn, one with binoculars and one with a telescope.  The binocular program consists of 40 objects while the telescope program has 100.  All you need to do is locate the object and write a short log entry about it.  Include the date, time, sky conditions, instrument characteristics, magnification and by remarks about the object.

I started the Explore the Moon - Telescope program on May 29, 2020 and want to write about each of the 100 objects.  I hope this will be a guide to help you locate these objects and understand more about them.  Each blog entry will be entitled: Explore the Moon - Object, and filed under the Explore the Moon section of the page.