Phases of the Moon
During its orbit around the Earth, the visibility of the Moon's illuminated part constantly changes.
Moon, moon phase, orbit of the Moon, orbiting of the Moon, new moon, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, lunar month, moon crescent, Earth, Sun, astronomy, geography
- Lunar cycle: 29.5 days
- Orbit of the Moon
- New Moon
- Waxing crescent
- First Quarter
- Waxing gibbous
- Full Moon
- Waning gibbous
- Last quarter
- Waning crescent
- Lunar phases seen from Earth (Northern Hemisphere)
- Montes Alpes
- Sea of Showers
- Sea of Cold
- Sea of Serenity
- Sea of Tranquility
- Sea of Fertility
- Sea of Crisis
- Sea of Nectar
- Sea of Clouds
- Sea of Moisture
- Sea of Cleverness
- Eastern Sea
- Sea of William Henry Smyth
- Ocean of Storms
- Montes Carpatus
- Montes Jura
- Montes Caucasus
- Montes Apenninus
- Montes Taurus
- Montes Pyrenaeus
- Montes Cordillera
- Plato (crater)
- Copernicus (crater)
- Gagarin (crater)
- Szilárd (crater)
- Zsigmondy (crater)
- Highland region on the Moon's other side
- Bolyai (crater)
- Eötvös (crater)
- Pasteur (crater)
The Moon is the fifth largest satellite
in the Solar System.
It orbits the Earth at a distance of 384 thousand kilometres. Its diameter is a quarter of the Earth’s. Its mass is only one eighty-first of that of the Earth. Therefore its gravity is weaker. Its surface warms up to 130⁰C during the day, but due to the strong heat radiation, it cools down to -160⁰C at night.
Its surface is composed mainly of volcanic rocks, covered by a thick layer of debris. We can see darker, lower-lying basins, so-called seas, and lighter, higher plateaus on the Moon.
The basins, with the mountains and
craters ringing them, were created by gigantic meteorite impacts. However, the volcanic rock layer and craters
created by geological processes prove that there also used to be active volcanoes on the moon.
So far the Moon is the only celestial body
apart from the Earth where man has ever set foot. US president John F. Kennedy announced on 25 May 1961 that during the course of that decade man would travel to the Moon and return safely back to Earth.
The first manned mission, Apollo 11, lifted off in July 1969, and on the 21st of July the first people to set foot on the Moon were Neil Armstrong and Buzz Aldrin. "That's one small step for man, one giant leap for mankind." These were the first words Armstrong spoke as he emerged from the lunar module.
Position of the Sun, the Moon and the Earth
- the orbit of the Earth
- orbital period: 365.25 days
- average distance from the Sun: 149,600,000 km
The Earth orbits the Sun. While the Earth orbits around the Sun once, it rotates around its axis about 365.25 times. This time period is one year. The orbital velocity of the Earth is 30 km/s.
The tilt of the Earth’s axis is 23.5°. As a result, within one year the angle of incidence of sunlight changes at the same location, and this is the reason why seasons change. Our planet rotates (relative to the Sun) once every 24 hours. Due to the centrifugal force caused by the rotation, the planet is somewhat flattened.
The Earth’s only natural satellite is the Moon, which formed about 4.53 billion years ago. The Moon’s gravity creates tides, which keep the axis of rotation of the Earth at an almost constant angle and slow down the planet’s rotation slightly (the length of one day increases by 0.002 seconds every 100 years).
The Moon is the fifth largest satellite
in the Solar System and the only natural satellite of the Earth.
It orbits the Earth at a distance of 384 thousand kilometres. Its diameter is a quarter of the Earth’s. Its mass is only one eighty-first of that of the Earth. Therefore its gravity is weaker.
The Earth orbits the Sun. While the Earth orbits around the Sun once, it rotates around its axis about 365.25 times. This time period is one year. The tilt of the Earth’s axis is 23.5°. Our planet rotates (relative to the Sun) once every 24 hours.
While orbiting the Sun, the Earth and the Moon orbit their common centre of mass (located below the surface of the Earth). The Moon is in synchronous rotation around the Earth: its axial rotation and orbital period are the same; therefore, we always see the same side. Its orbital period is 27.32 days, while the lunar phase period (from full moon until the next full moon) is 29.53 days. This difference results from the Earth's orbiting around the Sun, that is, its movement relative to the Moon. So it takes more than two days for the Moon to look the same.
The visible shape of the Moon is constantly changing; this change is repeated every 29 and a half days (a lunar month). These shapes are called lunar phases.
When the Moon is between the Sun and the Earth, the Sun illuminates the side facing away from the Earth; therefore, the part that faces us is hardly visible. This phase is called the New Moon.
Then the crescent Moon starts to 'grow', its shape increasingly resembling the capital letter D. In about one week, it reaches the First Quarter, when the Sun and Moon are seen at a right angle from the Earth, so we can see the eastern half of the illuminated part.
The Moon continues growing, and in another week we can see a bright disc. This phase is called the Full Moon. At this time the Moon is on the opposite side of the Earth from the Sun, so the Sun illuminates the entire side of the Moon that faces the Earth.
Then, as the Moon orbits the Earth, its visible part decreases and it starts to look like the letter C. In one week, it enters the Last Quarter phase. The Sun and the Moon are seen again at a right angle, now on the other side of the orbit compared to the first quarter. The western side of the Moon looks bright. Then it continues decreasing and it becomes invisible in the sky.
The lunar phases (the New Moon, First Quarter, Full Moon and Last Quarter) return cyclically.
The animation shows the two-seater Lunar Rover used in the Apollo 15 mission
This animation demonstrates how the Earth and the Moon were formed.
Lunar eclipses occur when the Moon passes through the shadow cone of Earth
The first calendars and time-measuring instruments were already used by ancient Eastern civilisations.
Neil Armstrong, one of the crew members of Apollo 11 was the first man to set foot on the Moon.
In 1946 a Hungarian scientist was the first person to detect radar echoes from the Moon.
When the Sun, Earth, and the Moon are arranged in a straight line, the Moon can partially or completely obscure the Sun.
The formation of the Sun and the planets started with the contraction of a dust cloud about 4.5 billion years ago.
The Moon is the Earth's only natural satellite
A ray of light is reflected or refracted at the boundary of two mediums with different refractive indices.
The orbits of the 8 planets in our Solar System are elliptical.
The rise and drop of sea levels caused by the gravitational force of the Moon.
A game to practise the use of analogue and digital clocks.