- Merry Christmas and Happy New 2013 Year
- Site anouncement
- Doomsday on 21 December 2012 - End of the world or the day of misunderstanding?
- And cameras are back
- We have changed our hosting.
- The observatory is off the Internet
- Merry Christmas and Happy New 2012 Year
- Iridescent cloud over the Rila Mountain
- Site changes
- Quadrantids meteor shower 2011
Perhaps the most famous celestial body in the night sky is the Moon. The moon is our natural satellite of Earth and it plays an important role in the life of our planet. There would hardly have been conditions for the existence of complex forms of life on Earth if the moon had not existed.It is stabilizing the movement of Earth around its axis, which is due to well-known terrestrial seasons. If we were living without our Moon, the Earth would probably be reversed uncontrollably around its solar orbit. This will lead to spontaneous and rapid changes of climates and we would not exist today as a human civilization. Perhaps this is why Mars is not inhabited by humanoids - the moons of Mars cannot stabilize rotation of the planet around its axis. We cannot deny that the world is full of strange and random phenomena. Only very slight modifications of any of them would have turned our notions about the world beyond recognition. If the moon did not exist – we may would not be on the Earth. If the moon is farther away from its current position, it would never have enjoyed a total solar eclipse. Probably we still would not know of the existence of the solar corona. Moon rotates at the same speed as the speed and rotation around the Earth; from Earth we only see one side of the moon. Figure 1 presents some basic data about the Moon and Earth graphically.
Fig. 1. Schematic presentation of data on the Earth and Moon.
The moon orbits in an elliptical orbit around the Earth, and periodically it is closer (perigee) or more away from us (apogee). The moon makes one complete revolution around the Earth with respect to fixed stars approximately every 27.3 days (sidereal period). Since the Earth is moving in its orbit around the Sun at the same time it takes the moon little more time to show the same phase of the light towards Earth, which is about 29.5 days (synodic period). For one sidereal month the moon passes through the farthest and nearest point to Earth. The maximum distance that the moon may be away from Earth is 406,720 km and the minimum distance between these two celestial bodies is 356,375 km. These extreme distances are calculated for the period of last some hundreds years (we know that the Moon is moving away from us). The average Earth-Moon distance is 384,400 km. Scaling scheme Earth-Moon system is shown by Fig 2.
Fig.2. Outline of the Earth-Moon system. Scaling scheme demonstrates the relationship between the actual size of celestial bodies and the distance between them.
Sequential passage of the Moon in its perigee or apogee is likely to coincide with the full moon phase. Then the apparent lunar diameter is larger or smaller, respectively (Fig. 3).
Fig. 3. Comparative images of the lunar disk at perigee and apogee.
Each year the moon passes through its perigee and apogee several times. This is not unloved; this is because the Moon has an elliptical orbit around our planet Earth. But rarely match the moments of crossing the Moon in its perigee and along with it to be a phase of full moon. The graphic bellow shows the moments of perigee and apogee of the Moon for 2011 by Figure 4.
Fig. 4. Passage of the moon in its perigee and apogee of 2011.
The diagram in Fig. 4 are plotted the positions of the Moon perigee and apogee in time and the moments of the full moon. We see that in 2011 on March 19 at 20 hours and 10 minutes the Moon is full and in perigee. Earth-Moon distance on that date will be 356,600 km. At that time, we call the moon "Super Moon" because its visible disk is larger than many other moments of the full moon. Early Native American tribes knew this full moon as the Full Worm Moon because this is the time of year when the ground would begin to soften and the earthworms would reappear. This moon has also been known as the Full Crow Moon, the Full Crust Moon, and the Full Sap Moon. Of course, this should not be considered a supernatural phenomenon, on which they could be attached supernatural events. Indeed, in such proximity, moon will be close to us again on October 26 but not in the phase of full moon. Such matching position near full moon and the Moon to the Earth happened on 19 Mach 1992 (356,561 km), on 08 March 1993 (356,552 km), and on 30 Jan 2010 (356,606 km). The next "Super Moon" will be on 14 November 2016 when the Moon will be closer to the Earth at a distance of 356,523 kilometers.