- Getting Started in Observational Astronomy
- Dark Eye Adaption - How We See In the Dark
- Light Pollution
- Using Star Charts and Measuring Distance
- Top Tips for Binocular Astronomy
- Moon Watching - How to Observe the Moon
- Buying Your First Telescope
- Your First Night With Your First Telescope
- Sky Orientation through a Telescope
- Polar Alignment of an Equatorial Telescope Mount
- All About Telescope Eyepieces
- Useful Astronomy Filters for Astrophotography
- How to Photograph Constellations
The Moon is always a delight, no matter what equipment you use to observe it. With your eyes alone you can see its phases, along with dark and bright patches on its face. Some detail, including large craters, appear through binoculars, but with a telescope, you'll see a great deal more, including craters, mountains and Maria (plains).
The Moon is the source of our ocean tides, subtle chronological cycles and the only other world that humankind has so far set foot upon. The Moon seems a familiar and tangible place. A quarter of a million miles away, it's 100 times closer than Venus. Given its proximity, brightness and large apparent size, it's easy to see why the Moon reveals a wealth of detail with even the smallest optical aid.
The Moon is around 4.47 billion years old and it was formed about 95 million years after the solar system. It's thought that the Moon was created when a huge piece of rock, about the size of planet Mars, collided with the Earth, breaking off molten rock which then formed the Moon. It is a natural satellite of the Earth and it is actually much further away from Earth than a lot of people realise - about 238,855 miles away! Another thing that you may not know is that the Moon is actually very slowly moving away from Earth, by about one inch each year.
The Moon is responsible for the tides our planet due to the gravitational pull of the Moon tugging at the sea in different directions each day. The Moon pulls the water in the oceans upwards making the oceans bulge, which creates high tide in the areas of Earth facing the Moon and on the opposite side. At the same time, in the remaining areas of the planet, the ocean water drains away to fill these bulges, creating low tides.
Moon Watching Basics
You may think that the best time to observe the moon is when it is a full moon. While the Moon may appear full and bright at this time, the shadows on the moon surface are at their shortest which makes it much harder to pick out individual features.
It's far better to wait until the phase of the Moon has changed and a shadow line, called a terminator is visible. A terminator is the boundary between the illuminated section of the Moon and the area in shadow. Observing the terminator is where the Moons mountains and craters are most clearly seen. The amount of the Moon visible and the position of the terminator are called Moon Phases.
While you can observe the Moon with the naked eye, you will get a much better view through a pair of binoculars. This will vastly improve the detail you can see on the surface.
The first thing most poeple notice when looking at the Moon are the dark areas called seas. They are not actually seas, rather large basaltic plains. The most famous of these are Mare Imbrium, Mare Serenitatis and Mare Tranquillitatis. The next thing people notice is the craters, remnants of asteroid and meteor impacts, Copernicus and Tycho are two examples of easy to see craters.
Moon Watching with a Telescope
You can also see a surprising amount of detail on the moon with binoculars, but with even the smallest telescope, a whole new world appears before you, ready to explore.
Concentrate your observing along the terminator, the boundary between light and dark. The sun is rising along this line, and so the shadows are at their maximum length. In fact, if you watch for a few minutes, you can actually see the shadows change as the sun rises.
A lot of beginners are surprised at how bright the Moon is in a telescope. In fact, it is only as bright as a road surface on a sunny day, but it seems much brighter because we're usually observing the Moon in a dark sky from a dark location. If the brightness bothers you, try observing before the sky is completely dark, or if you can turn some lights on at your observing location. Alternatively there are astronomy filters which can screw into a telescope eyepiece which will cut down the glare from the Moon.
As the Moon gets closer to a full Moon, the terminator moves closer to the edge of the Moon, and it gets harder to see detail. A few nights after full, the Moon starts to get interesting in the telescope again but at this point, many people lose the Moon. That's because the Moon, in its orbit around the Earth, rises about 50 minutes later each night. By third quarter, the Moon rises around midnight and is high in the southern sky at dawn. If staying up late to observe the Moon doesn't agree with, you can try observing it first thing in the morning instead.
Features of the Moon
There are so many things to see on the Moon. Here is a checklist for you to follow and check off each sight as you discover them. This list is also my checklist, each item I've photographed has a photo next to it.
The terminator is the area where lunar day meets lunar night. It is a region of shadows perfect for revealing features on the Moon's surface.
There are 14 officially named valleys on the Moon, the longest around 600km. Most are named after nearby craters. One of the most famous is the 150km long Vallis Alpes which cuts across the northern Montes Alpes and almost bridges the Mare Imbrium and Mare Frigoris.
Vast dark plains of solidified magma from volcanic eruptions that occurred around three billion years ago notable for both their dark appearance and the fact that they are largely absent from the moons far side. One of the most distinct is the 555km wide Mare Crisium which is just visible to the naked eye.
A ubiquitous lunar feature varying in size from microscopic pits to sprawling depressions up to 350km in diameter. Anything larger is a basin. Some craters were formed through volcanism but the majority are the result of ancient impacts. The 84km wide Tycho is a peerless 108 million-year-old example.
The oldest and largest impact craters on the Moon exceeding 350km in diameter. All lunar maria are found within them. The south pole Aitken basin on the moon's far side holds the record for being the largest at around 2600 km; the biggest on the near side is the Imbrium Basin, shown here, which stretches across 1160km of the lunar surface.
The moons peals are named in two ways: Montes for mountain ranges and Mons for singular peaks and massifs. The most spectacular of the 18 named lunar ranges in the gently curved 600km long Montes Apenninus. It forms the southeastern edge of the Imbrium Basin. Mons Huygens the moons tallest mountain at around 5500m high soars skyward here.
Sunlight reflected from the Earth that faintly illuminates the dark portion of the Moon's disc.
Bright streaks of material thrown out during crater forming events.
The moon is between Earth and the sun, and the side of the moon facing toward us receives no direct sunlight; it is lit only by dim sunlight reflected from Earth.
Under dark skies you can see the dark side of the Moon glowing in Earthshine.