The appearance of Earth and Moon through a telescope depends on the Planetshine phenomenon.
Planetshine is a phenomenon that happens when reflection from a planet lights up the dark side of the Moon. It is generally a fade illumination of one part of the Moon, particularly during the crescent phase.
The reflection of the planet is usually known as Planetlight, which is the scattered reflection of the sunlight from the planet – usually Earth.
Earthshine is a dull glow that allows us to see the dark side of the Moon. It happens because the sunlight reflecting off the surface of Earth and reaches back onto the Moon.
To understand the phenomenon, it is important that you know that Planet Earth is more reflective than the Moon. It might sound surprising, but it’s a fact and a hundred percent true.
To add to your surprise, you can compare the reflectivity of the Moon, and it turns out that the asphalt is a better reflector than the Moon itself.
Earth is four times larger than the Moon. Therefore, it’s not absurd to think of Earth as a better reflector and brighter when seen from the surface of the Moon.
Looking at the Moon with a Telescope
When we start using the telescope, nearly everything excites us. The first thing that anyone wants to observe with a telescope is the surface of the Moon, which has many twists, turns, and folds. Let’s take a deep dive into the hidden valleys of the Moon.
The Surface of the Moon has different geological features ranging from basins filled with lava, mountains, deep pits, and others. The cracks in the surface of the Moon are generally known as the rilles – a German word for the groove.
The rilles of the Moon – also known as rimae are as old as almost 3.6 billion years. They take up many forms. However, the main types of these rilles are:
- Sinuous Rilles
- Arcuate Rilles
- Straight Rilles
The Sinuous rilles are made from lava that flowed into the surface of the Moon and caused it to become carved in the passage.
The Arcuate rilles are concentric circles that appear on the surface of the Moon due to lava that fills up in the basin, cools, and ultimately contract.
Straight rilles are the linear or straight roads formed due to dropping between the two parallel lines.
Looking at the Earth from the Moon
Although there is so much speculation about an American astronomer going to the Moon, there is no significant conclusion that we can from it. All the understanding that we have about the Moon is what we see through the telescope on the lunar service.
The Moon undergoes different phases throughout its lifecycle – from one appearance to the other.
The New Moon phase of the lunar cycle is not visible from the Earth’s surface, as it is completely covered in shadows.
The right side of the Moon becomes lit by the Earthshine, and what we see is a sharp thin crescent.
Although the quarter moon looks like a half-moon, the astronomers normally call it quarter according to the lifecycle events – rather than the shape of it.
In this phase, the illuminated portion of the Moon has increased significantly, and apart from a very small portion, most part is brightly lit.
The full moon phase of the lunar lifecycle shows a completely round full moon – that shines its strongest.
The right side of the Moon is being taken up by darkness, illuminating only the left part of it.
Contrary to the First Quarter, where the red edge was lit, in the last quarter, the left edge of the Moon is lit up by the Earthshine.
In this phase, the left edge will start to disappear, and there will be no one before a new one appears in the sky.
All these phases appear different, as we see from the Earth. Similarly, the Earth also appears differently if we see it from the surface of the Moon. You must be wondering, what would it look like, right?
The Mystic Journey of Earth and Moon
At the time of a Full Moon – where it is shining brightly, Earth will appear as a large circle from the lunar surface. However, as the Moon turns into a thin crescent, the Earth will take the form of a large gibbous phase.
This is because at the times of crescents – be it waxing crescent or the waning crescent, and the Earth shines the strongest onto the lunar surface. Due to this reason, the thin crescent we usually see are illuminated by the Earthshine.
What typically happens is that Earth lights up the dark portion of the Moon’s side that faces the Earth. The light reflects back to the Earth (which lights it up), and hence, we see the Moon glowing gently.
The Astronomers are able to see the Earth-lit part of the lunar surface with the help of different telescopes. They also reveal some of the details and features of the Moon surface. A pit known as the Crater Aristarchus appears very brightly as we see near the western side of the Moon.
It is a well-supported fact that Earthshine is happening at all times, as Earth continues to give off its light to the Moon. However, it is visually apparent only when the Moon is in the form of a thin crescent.
The reason to support this fact explains that it is quite difficult and highly unrecommended to light at the full bright lunar surface with the assistance of a Telescope, as it could be damaging to your eyes.
Moreover, the Moon’s shine overwhelms your eyes, and you are not able to see anything there. Hence, the phenomenon of Earthshine is only visible when the Moon is in the form of a thin crescent.
All the amazing phenomenon of Planetshine, Earthshine, the phases of the Moon, how Earth and Moon appear from the surface of each other are all because of the evolution of telescope. The reflecting telescopes that employ the use of mirrors instead of lenses are particularly important to observe the changes and celestial happenings in the sky.