Uncategorized Archives - Planet Seekers

The Short answer is that the the Moon reflects sunlight that hits it. But the Sun is so bright that even this much reflection looks very bright to us. We all know that it is sunlight that makes life on earth possible, but it does more than that. Everything we see in and around our space neighborhood is thanks to the solar rays, including the shining bright moon in the night sky. If we take the moon, it is quite insignificant in terms of the illuminance when compared to other cosmic bodies. It only seems bright at night because of the fact that it is the closest to the earth and also because our surroundings are generally dark during nighttime. If we do a comparative study, it is found that the moon is one of the least reflective objects that can be observed in the night sky. Before we can fully understand why the moon looks so bright during nights, we must understand how we judge the luminosity of an object. In general, we are able to see objects because they direct light back to our eyes. This is achieved in one of two ways: either the body produces its own light or it reflects light existent in its surrounding. The moon only reflects about 11 or 12 percent of light from the sun. Objects that create light tend to be very bright since they achieve this through complex chemical reactions, for e.g. a light bulb, a campfire, or the sun. In astronomical terms, the stars are the only bodies that produce visible light and therefore are the brightest bodies in the universe. Planets, satellites, and asteroids do not have the ability to produce visible light. They are limited to reflecting the light that is being produced by a nearby star, or in case of the moon, the sun. If a planet becomes hot enough to start to produce visible light, it will no longer be considered a planet and will be redefined as a star. Video by Astronomic Since planets and natural satellites (including our Moon) cannot produce light on their own, the only reason we can observe them in the vast darkness of space is that they reflect light from the sun, thus illuminating their cosmic bodies. The amount of sunlight that gets reflected upon reaching a cosmic body depends generally on its composition, atmosphere, and topography. Conversely, it can be deduced that the more reflective a cosmic body is, the brighter they appear when observed through a telescope from earth. The quantum of reflection, as discussed previously, depends heavily on the topology of the body and therefore some types of bodies are more reflective than others. For e.g. snow, rough ice and clouds are highly reflective which is why planets like Earth and Venus that are covered in clouds appear brighter on a telescope than say, a rocky asteroid in the same distance. The moon looks stupendous, shining bright in the night sky, but its perceived brightness is not fixed. It is contingent upon the position of the moon in orbit and the angle it is creating at any given time with the sun. The scientific term for explaining and recording these changes in the intensity of brightness of the moon is called ‘phase’. Before we can delve deeper into this, it is important to know that our moon, on account of the earth’s gravitational pull, is tidally locked and therefore only shows one face towards the earth. The moon, from our perspective, is the brightest when it is 180 degrees from the sun. To imagine this, picture a straight line with the sun, the earth and the moon lined straight. In this configuration, the side of the moon facing the sun is illuminated and it is what we call a full moon. The new moon, however, is completely the opposite. To imagine this, picture the moon positioned between the sun and earth. At this configuration, the side of the moon that is reflecting sunlight is facing the sun, and therefore, the moon appears to be non-existent in the night sky. In the time before and after a full moon, the moon transits through an orbit around the earth where the moon only partially reflects the sunlight incident upon it. Observed from the earth, we see a bright sliver of the moon that stands out against the faintly lit borders of it which are called earthshine. To understand the concept at hand in a practical setting, let us consider this experiment. To do this, you will require a lamp or a flashlight and a ball. We use the lamp to simulate the sun, the ball to simulate the moon and you will be the earth. Let us use this experiment to demonstrate how a full moon might occur. To begin, darken the room and turn on the lamp such that it is the only source of light in the room. Now, sit with your back to the lamp and hold the ball out in front of you in a straight light. You will observe that the light from the lamp illuminates the ball on the surface that is facing you while the other surface of the ball is still dark. This is exactly what happens to our moon in a full moon night. The ball (or moon) appears very bright by reflecting the light of the lamp (or sun) to your eyes. Now, let’s consider a half-moon, also known as a first-quarter moon or a third-quarter moon. To observe that, turn in your chair so that the lamp (or sun) is direct to your left. Now, hold the ball in front of you as you did in the previous case. You will observe that instead of a full well-lit ball, not the ball is only partially lit in one side and you can only see half of it. In fact the experiment is so accurate that you can compare your observations to pictures of a half-moon night and the similarities would be striking. More importantly, if you take a closer look, you will notice that the side of the ball that is lit up is not as brightly lit as it was during the full moon experiment. The reason for it again lies in reflection. It is still getting the same light as before but since you are no longer between the ball and the lamp, not all of the light is getting reflected in your direction, therefore the apparent loss in the intensity of brightness. Related questions What makes the moon so bright? The moon shines because its surface reflects light from the sun. And despite the fact that it sometimes seems to shine very brightly, the moon reflects only between 3 and 12 percent of the sunlight that hits it. The perceived brightness of the moon from Earth depends on where the moon is in its orbit around the planet. What is the moon in cosmic terms? The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, and the largest among planetary satellites relative to the size of the planet that it orbits (its primary).