“That’s one small step for man, one giant leap for mankind.”
On July 20th, 1969, more than half a billion people, scattered all around the Earth, were
glued to their television sets as they watched astronaut Neil Armstrong become the first
human being to set foot upon another world.
It was a defining moment in history, not just for the United States but for the people of
all nations, as humanity took its first literal and tentative steps towards becoming a spacefaring civilization.
Hello everyone, I’m Darrell Heath with UA Little Rock’s College of Arts, Letters,
and Sciences; welcome to The Night Sky.
Whenever I’m showing off the moon in my telescope at a star party, I invariably get
asked the question: “Is it possible to see the flag the astronauts left behind on the moon?”
I wish that we could, but the answer of course is, “no”.
The smallest crater you can see with your unaided eye is Copernicus, which is about
60 miles across.
Use a pair of binoculars and you can begin to pick out craters that are around 6 miles across.
With a good backyard telescope, you can begin to resolve craters down to nearly a half-mile
across.
To view a flag that is about 4 feet long, you would need an optical telescope that has
an aperture of nearly 700 feet.
The largest such telescopes on Earth today only have apertures of around 30 feet across.
NASA’s Lunar Reconnaissance Orbiter, a robotic spacecraft currently orbiting the moon and
mapping its surface in exquisite detail, can resolve objects down to a meter across, so
it can just barely make out the flag left by the Apollo 17 astronauts.
Its sharp-eyed cameras can even pick out larger pieces of left-behind equipment as well as
the trails the astronauts made in the lunar dust as they explored the moon’s surface.
While you and I are unable to see such details, that doesn’t mean we can’t go into our
backyards with a small telescope and explore the Apollo landing sites for our very own.
And that’s exactly what we are going to do in this episode of The Night Sky.
From 1969 to 1972 there were a total of 6 Apollo missions that landed upon and explored
the lunar nearside (the Earth-facing side of the moon) at 6 different landing sites.
Each site having been chosen to explore different aspects of the moon’s various geological
terrains.
An important tip in finding these sites, is to get familiar with the lunar terrain before
you start hunting and to do that, I suggest looking over a moon map.
You can print out a nice, generalized map from the NASA Night Sky Network.
Just go to this address: https://nightsky.jpl.nasa.gov
Under the “Find Content” menu, just type in “moon map” in the search field and
then click the box for “Outreach Resources” and hit enter.
You should then see a link for a Skywatchers Guide To The Moon.
This is the map you want.
Check with your local library or bookseller in order to find various lunar field guides,
moon atlases, or large-scale moon maps.
Alternatively, you can explore the moon by using websites such as Google Moon (https://www.google.com/moon/)
or NASA’s moon website (https://moon.nasa.gov/about/in-depth/).
Finally, you can also explore the moon and the Apollo landing sites by using various
astronomy apps such as the latest versions of Sky Safari, Star Walk 2, or LunarMap Lite.
Whichever lunar guide you decide to use, just keep in mind that, depending upon the telescope
that you use, the moon’s image may be correct, upside down, or mirror reversed.
Most of the maps and guidebooks will tell you how the images are oriented, so make sure
that you use the ones that will reflect what you are seeing in your particular scope.
Okay, if you are ready, let’s step outside and take a look at the moon.
One of the first things that we notice is that it seems to have both light and dark
terrain features.
The lighter regions are the lunar highlands, made up mostly of a fine-grain/low density
rock known as anorthosite.
Rock samples from the lunar highlands, returned to us by the Apollo astronauts, have been
dated to around 4.5 billion years, very close to the estimated age of the Earth.
The highlands then are the oldest parts of the lunar terrain.
There have been various ideas put forth to explain how the moon formed, but the one that
seems to best match our observations is the Giant Impact Hypothesis.
According to this model, the moon was actually given birth to about 100 million years after
the Earth had formed when a Mars-sized object collided with the Earth at an oblique angle.
The moon’s parent bodies mixed together as one, but portions of the mantles from both
were flung out into space to form a ring of molten material around the new Earth, this
ejected material eventually coalesced to form the moon.
Initially, the young moon’s surface was molten and slowly cooled over time, as it
did so, the low-density material floated to the surface to make the lunar highlands.
But just as the moon was created out of violence, so to would its surface become sculpted by it.
After any great construction project there is going to be leftover scrap material, so
too with the formation of the solar system.
For about a billion years after the moon was formed, both it and the Earth were bombarded
by large leftover objects that did not go into the making of a planet.
Some of these objects were large enough to create huge basins upon impact with the moon.
Later, and for reasons we don’t quite understand, magma from the moon’s interior welled up
to fill in the basins.
As the magma cooled, it formed an iron-rich, coarse-grained rock called basalt.
These dark terrain features are called Maria, the singular is “Mare” and is Latin for
“sea”, because they were once thought to contain water.
The Maria represent the lunar lowlands.
The first two Apollo mission landing sites were in lunar mare and were chosen largely
for safety reasons since these terrain features have relatively flat surfaces with fewer craters.
Later mission sites were selected for scientific as well as safety reasons and included areas
within the highlands.
Okay, on to finding and observing the various lunar landing sites.
With the exception of Apollo 12 and14, the Apollo 11, 15, 16, and 17 landing sites can
be seen during the times between first quarter and full phases.
The Apollo 12 landing site is best observed sometime between full and last quarter phases
while Apollo 14 can be observed between waxing gibbous and last quarter phases.
With the first manned lunar landing, Apollo 11, astronauts Neil Armstrong, Buzz Aldrin,
and Michael Collins entered the history books.
Using the Eagle lander, Armstrong and Aldrin descended to the lunar surface on July 20th,
1969 while Collins remained in orbit aboard the Columbia Command Module.
Tranquility base here, the Eagle has landed.
The Eagle lander set down near the lunar equator above the southern edge of the Sea of Tranquility.
To find the site, first locate the largest nearby crater, Theophilus.
Look north of Theophilus to find a smaller crater named Moltke.
Immediately to the northwest of Moltke is Tranquility Base, the landing site of Apollo 11.
For an observing challenge, and if you have a large enough telescope, see if you can find
three small craters that are lined up in a row just above Moltke and Tranquility Base.
These three craters are named in honor of the Apollo 11 astronauts.
From west to east are Aldrin, Collins, and Armstrong.
Armstrong and Aldrin spent a total of 2 hours and 31 minutes of EVA on the moon.
They collected nearly 50 pounds of lunar material, took some wonderful panoramic photos, deployed
a solar wind experiment, and set up a series of reflectors that allows us to bounce lasers
off of in order to determine the moon’s precise distance at any given time.
The astronauts also left behind a plaque, which reads: "Here men from the planet Earth
first set foot upon the Moon, July 1969 A.D.
We came in peace for all mankind.”
On November 19, 1969, just four months after
Apollo 11, Pete Conrad and Alan Bean made a precision landing in the Ocean of Storms
with the Intrepid lunar module.
Astronaut Richard Gordon remained aboard the Command Module, the Yankee Clipper.
The Apollo 12 landing site will be easier to locate than the Apollo 11 site.
Assuming that your telescope inverts your image, just locate the distinctive Copernicus
Crater and orient it to where it is at the bottom of your field of view.
Just to the upper right, you will find the crater Reinhold and then, just to its upper
right, is Lansberg.
The landing site is just to the upper left of Lansberg.
On February 5th, 1971, the Antares Lunar Landing Module set down upon the moon’s surface
with astronauts Alan Shepard and Edgar Mitchell,
Astronaut Stuart Roosa remained in orbit aboard the Kitty Hawk command module.
Apollo 14 landed in the Fra Mauro highlands,
This is another fairly easy site to locate as it is placed very near to a rather conspicuous,
and often imaged crater chain.
The three craters making up this chain are Arzachel, Alphonsus, and Ptolomaeus.
Heading to the right of Ptolomaeus and you will see the crater Parry, the landing site
is just to its lower right.
Shepard and Mitchell collected 94lbs of lunar rock, one of which, named “Big Bertha”,
is made of granite and quartz, not something you would typically find on the moon.
On July 30th, 1971, Apollo 15 Falcon lander, set down on the eastern edge of the Sea of
Rains near the Apennine Mountains.
Astronauts David R. Scott and James Irwin were the lunar explorers on this mission while
Al Worden remained in orbit aboard the command module Endeavour.
To locate the landing site, first go to the crater Archimedes.
To the crater’s left is another conspicuous impact crater, Autolycus, to its upper left,
within a break in the curve of the mountains, is Apollo 15’s landing site.
It was on this mission that the first lunar rover was used, allowing the astronauts to cover
more terrain and to do more and better science.
On previous missions, the astronauts covered terrain that could be measured in hundreds
of meters, now, they were able to cover tens of kilometers.
On April 21st, 1972, Apollo 16 set down in the lunar highlands, a region that had not
yet been explored by Apollo astronauts.
The site is located in the Descartes Highlands in an area known as the Cayley Formation,
a hilly, furrowed terrain that was thought to be fairly representative of the lunar highlands.
To find the site, let’s go back to our old friend Theophilus Crater.
Head west from Theophilus until you come to the next large-ish crater, Kant.
From Kant, travel west for about the same distance again until you come to a small crater
named Dolland-E, the landing site is immediately north of this crater.
This time, our two moon walking astronauts were John Young and Charlie Duke, with Tom
Mattingly remaining in orbit aboard the Casper command module.
Young and Duke spent a total of 20 hours and 14 minutes of EVA time on the moon, collected
over 200 pounds of rocks and traversed over 25 kilometers with the aid of the lunar rover.
On December 11th, 1972, Apollo 17, the last manned mission to the moon, landed in the
Taurus-Littrow Mountains, a small depression in the Taurus Mountains that rim the southeastern
edge of the Sea of Serenity and a northern edge to the Sea of Tranquility.
To find it, first locate the large crater known as Posidonius and then head south to
find craters Littrow and Vitruvius, the landing site is located in a valley in between the
two but lies closest to Littrow Crater.
Astronauts Gene Cernan and Harrison Schmitt (a trained geologist) spent 22 EVA hours on
the lunar surface over a 3-day period.
During that time, they collected rock samples from both highland material and young volcanic
deposits, all within the same landing site.
With the aid of the lunar rover, Cernan and Schmitt were also able to traverse and explore
some 32 kilometers of the moon’s surface.
As Gene Cernan took his last steps upon the moon, he said these final words:
And, as we leave the Moon at Taurus-Littrow, we leave as we came and, God willing, as we
shall return, with peace and hope for all mankind.
Godspeed the crew of Apollo 17.”
So what does the future hold for humankind on the moon?
The moon is still a viable target for scientific explorations and commercial ventures.
NASA plans to put humans on the moon by the year 2024 and many other countries such as
Russia and China are also planning manned missions to the lunar surface.
Not only that, but there are several plans to establish a permanent human presence on
the moon, which can serve as launching point to Mars and other parts of the solar system.
Billionaires such as Space X’s Elon Musk and Amazon and Blue Origins CEO, Jeff Bezos,
have ambitious plans to commercialize space travel and to set up bases on the moon and Mars.
Both are making strides in their plans and just what the future holds for them remains
to be seen.
Either way, it’s something to think about the next time you step outside and look up
at the moon in both awe and wonder.