Earth/Sun/Moon Relationships
Moon
The Moon is Earth's constant companion in space. It orbits the Earth about once a month (approximately 27 days) and is about 250,000 miles away. It's featured in poems, songs, and stories. But where did it come from? There are numerous theories, but only one stands out and seems to explain the qualities we find on the Moon. It's theorized that sometime after the Earth formed, a small planet called Theia that was about the size of Mars smashed into Earth. The force of the collision obliterated Theia and almost destroyed the baby Earth by almost ripping it apart. Luckily for us, the Earth was just big enough to pull itself back together by gravity. The debris from the collision orbited the Earth as a ring and begin to coalesce or clump together. Eventually, the Moon formed.
The Moon has two distinct landscapes: maria and highlands. The maria are dark, somewhat smooth areas made of basalt. The highlands are bright, heavily cratered areas made of something called anorthosite. We believe the maria to be younger because they have fewer craters than the highlands. We have walked on the Moon 6 times. From 1969-1972, NASA sent 7 missions to the Moon. 6 landed and 2 men from each mission walked around on the Moon collecting rock samples and geologic data. Apollo 11 was the first to land on the Moon. Neil Armstrong was the first man on the Moon. We have not been back since 1972. We have recently discovered that there is quite a bit of water under the surface of the Moon.
The Moon is Earth's constant companion in space. It orbits the Earth about once a month (approximately 27 days) and is about 250,000 miles away. It's featured in poems, songs, and stories. But where did it come from? There are numerous theories, but only one stands out and seems to explain the qualities we find on the Moon. It's theorized that sometime after the Earth formed, a small planet called Theia that was about the size of Mars smashed into Earth. The force of the collision obliterated Theia and almost destroyed the baby Earth by almost ripping it apart. Luckily for us, the Earth was just big enough to pull itself back together by gravity. The debris from the collision orbited the Earth as a ring and begin to coalesce or clump together. Eventually, the Moon formed.
The Moon has two distinct landscapes: maria and highlands. The maria are dark, somewhat smooth areas made of basalt. The highlands are bright, heavily cratered areas made of something called anorthosite. We believe the maria to be younger because they have fewer craters than the highlands. We have walked on the Moon 6 times. From 1969-1972, NASA sent 7 missions to the Moon. 6 landed and 2 men from each mission walked around on the Moon collecting rock samples and geologic data. Apollo 11 was the first to land on the Moon. Neil Armstrong was the first man on the Moon. We have not been back since 1972. We have recently discovered that there is quite a bit of water under the surface of the Moon.
Moon Phases
The Moon appears to change size and shape in the night sky. In reality, the Moon stays the same size and shape, but we only see parts of it as sunlight reflects off of it. The Moon is in tidal lock with the Earth which causes us to see only one side all the time. But, when it's between Earth and the Sun, we can't see it. This is called a New Moon. As it revolves around the Earth (about one month), it rotates once. This slow motion and slow appearance of light on its surface makes it look like it's getting bigger or smaller. As it "grows" we say it's waxing. When it "shrinks," it's waning. It goes through these phases: New; Waxing Crescent; First Quarter; Waxing Gibbous; Full; Waning Gibbous; Third Quarter; Waning Crescent; New. |
Eclipses
When the Sun, Earth, and Moon are in a direct line, an eclipse can occur. When the Moon passes between the Sun and Earth, it can block out the Sun. This is called a Solar Eclipse. This happens during the New Moon phase. All we see of the Sun during this eclipse is the corona or halo. When the Moon passes behind the Earth, it can pass through Earth's shadow. This is a Lunar Eclipse. This happens during the Full Moon phase. The Moon can appear red during a lunar eclipse because the sunlight is bent or refracted by Earth's atmosphere and stripped of all but red light. That gives the Moon a blood-red color, making a Blood Moon. |
Tides
The Moon has a great effect on the Earth. Even though it has only 1/6th the gravity of the Earth, it's enough to pull on our planet. The area most affected by the Moon is the ocean. The Moon's gravity causes it to rise and fall twice a day. We call these tides. When the Sun, Earth, and Moon are in a line (during New Moon and Full Moon), the high tides are at their highest and low tides are at their lowest. This is called a Spring Tide. It happens twice a month. When the Moon and Sun are at a right angle to each other (1st and 3rd quarter phases), the high tides aren't very high and the low tides aren't very low. This is called a Neap Tide. It also happens twice a month. |
Sun
The Sun is the only star in our Solar System. It's a fairly average star and is often described as a yellow dwarf star. However, compared to everything else in our Solar System, it's HUGE!!! It contains about 99.8% of the total mass of the Solar System. 1.3 million Earths could fit inside it. It's gravity holds everything in the Solar System in orbit around it. The energy and light it emits keeps life going on our planet. At the center of the Sun is the core. The core is the location of nuclear fusion (two atoms smash together and stick). Nuclear fusion releases an incredible amount of energy. Hydrogen fuses into helium under intense heat and pressure. The heat from the fusion travels away from the core, first passing through the radiative zone and then into the convective zone. Convection is one of the most important methods of heat transfer in the universe: hot stuff rises and cold stuff falls. We see it in the atmosphere/weather (warm air rises/cold air falls), in the Sun, in the Earth's mantle, in the oceans, and many other locations. It can take several thousand years for the heat to make its way from the center of the Sun to the "surface" (there is no true surface to the Sun as it is a giant ball of superheated gas called plasma). Finally, the heat passes through the outer layers of the Sun: the photosphere ("light" sphere; this is what we see); the chromosphere ("color" sphere); and the corona ("crown" or halo). On the photosphere, we can see dark sunspots which are actually areas of magnetic discharge that cause the temperature to drop a little and make it appear darker. The chromosphere is alive with solar flares, prominences, and coronal mass ejections which can cause damage to satellites and electrical equipment here on Earth. |
Seasons
The Earth is tilted about 23.5 degrees from the vertical. Over great lengths of time, the Earth wobbles like a top as it travels around the Sun. However, over a short time frame as a year, the northern hemisphere either points away from or toward the Sun. This causes our seasons. When the northern hemisphere is pointed toward the Sun, we experience summer as we are getting more direct rays of sunlight. The day in which the northern hemisphere is directly pointed at the Sun is called the summer solstice and usually happens on June 21 (or 22). This is the longest day of the year as it stays daylight longer. Incidentally, we are also at the greatest distance from the Sun around this time (typically in July). When the northern hemisphere is pointed away from the Sun, we experience winter. The rays of sunlight are less direct and weaker. The shortest day of the year is the winter solstice and usually happens on December 21 (or 22). We are at our closest to the Sun in January. When neither hemisphere is pointed toward or away from the Sun, we experience spring and fall. The first day of each of those is called an equinox as we have equal amounts of night and day. |