Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
Some Useful Words For You To Remember
Earth – our home planet
Moon – the earth’s satellite
Sphere – a round object e.g. a ball
Revolve – to go around a point
Orbit – to travel around another body
Spin – to around a point
Rotate – to turn on an axis/centre, like a roundabout in a playground
Axis – a fixed point which an object spins around
Sunrise – the time of day when the sun comes up
Sunset – the time of day when the sun goes down
North – a point on the compass
South – a point on the compass
East – a point on the compass
West – a point on the compass
Below is a picture of a compass showing north, south, east and west!!
The Earth, The Sun And The Moon
The moon is about a quarter of the size of the earth, the sun is about 110 times the size of the earth!!! The moon orbits the earth and the earth orbits the sun. The sun rotates creating day and night. During the day we see shadows at night we don’t because there is no sunlight!!
The sun rises in the morning, it is at its highest point at midday and it sets in the evening. When it is day on one side of the world it is night on the other.
The sun rises in the east and sets in the west. The days are longer (i.e. there is more daylight hours in the summer than there is in the winter).
The moon orbits the earth every 28 days.
The earth orbits the sun once every year or 365 days (i.e. once every twelve months).
Sunlight also hits the moon, but to varying degrees, that is why you can sometimes see more of the moon than at other times.
Below are different images of the moon with varying amounts of sunlight on it.
Below are is a picture of the earth, the sun and the moon and how they appear in relation to each other.
Below is a picture of the earth.
You can also view a 3D version of the earth by clicking here!
Below is a picture of the sun.
Below is a picture of the moon.
Man On The Moon
Below is an image of a man (known as an astronaut) on the moon’s surface!! Cool!!
More About The Earth
The Earth is the third planet from the Sun and is the largest of the terrestrial planets in the Solar System, in both diameter and mass. It is also referred to as the Earth, Planet Earth, and the World, and in some contexts, Gaia and Terra.
Home to millions of species including humans, Earth is the only place in the universe where life is known to exist. Scientific evidence indicates that the planet formed 4.54 billion years ago, and life appeared on its surface within a billion years. Since then, Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful radiation, permitting life on land.
Earth's outer surface is divided into several rigid segments, or tectonic plates, that gradually migrate across the surface over periods of many millions of years. About 71% of the surface is covered with salt-water oceans, the remainder consisting of continents and islands; liquid water, necessary for all known life, is not known to exist on any other planet's surface. Earth's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inner core.
Earth interacts with other objects in
outer space, including the
Sun and the
Moon. At present, Earth orbits the Sun once for every roughly 366.26 times it rotates about its axis. This length of time is a
sidereal year, which is equal to 365.26
solar days. The Earth's axis of rotation is
tilted 23.4°
away from the
perpendicular to its
orbital plane, producing seasonal variations on the planet's surface with a period of one
tropical year (365.24 solar days). Earth's only known
natural satellite, the Moon, which began orbiting it about 4.53 billion years ago, provides ocean
tides, stabilizes the axial tilt and gradually slows the planet's rotation. A
cometary bombardment during the early history of the planet played a role in the formation of the oceans. Later,
asteroid impacts caused significant changes to the surface environment. Long term
periodic changes in the Earth's orbit, caused by the gravitational influence of other planets, are believed to have given rise to the
ice ages that have intermittently covered significant portions of Earth's surface in glacial sheets.
More About The Sun
The Sun is by far the largest object in the solar system. It contains more than 99.8% of the total mass of the Solar System (Jupiter contains most of the rest).
It is often said that the Sun is an "ordinary" star. That's true in the sense that there are many others similar to it. But there are many more smaller stars than larger ones; the Sun is in the top 10% by mass. The median size of stars in our galaxy is probably less than half the mass of the Sun.
The Sun is personified in many mythologies: the Greeks called it Helios and the Romans called it Sol.
The Sun is, at present, about
70% hydrogen and
28% helium by mass everything else ("
metals") amounts to less than 2%. This changes slowly over time as the Sun converts hydrogen to helium in its core.
More About The Moon
The Moon (Latin: Luna) is Earth's only natural satellite, and is the fifth largest one in the Solar System. The average centre-to-centre distance from the Earth to the Moon is 384,403 km, which is about thirty times the diameter of the Earth. The Moon has a diameter of 3,474 km — slightly more than a quarter that of the Earth, and about two-thirds of the average east–west distance across the United States. This means that the volume of the Moon is about 2 percent that of Earth. The gravitational pull at its surface is about 17 percent of the Earth's. The Moon makes a complete orbit around the Earth every 27.3 days, and the periodic variations in the geometry of the Earth–Moon–Sun system are responsible for the lunar phases that repeat every 29.5 days.
The Moon is the only celestial body to which humans have travelled and upon which humans have landed. The first artificial object to escape Earth's gravity and pass near the Moon was the Soviet Union's Luna 1, the first artificial object to impact the lunar surface was Luna 2, and the first photographs of the normally occluded far side of the Moon were made by Luna 3, all in 1959. The first spacecraft to perform a successful lunar soft landing was Luna 9, and the first unmanned vehicle to orbit the Moon was Luna 10, both in 1966. The United States (U.S.) Apollo program achieved the only manned missions to date, resulting in six landings between 1969 and 1972. Human exploration of the Moon ceased with the conclusion of the Apollo program, although several countries have announced plans to send people or robotic spacecraft to the Moon.
The Seasons
Our planet takes just over 365 days to orbit the Sun – the basis of our calendar year
The Earth's axis is tilted at an angle of 23.5 degrees.
This means that different parts of the globe receive varying amounts of sunlight during the year, creating the seasons.
Day And Night
Imagine a rod going from the north pole through the centre of the Earth and out of the south pole. Over the course of 24 hours, the planet spins once around this central rod or 'axis'. When we're facing the Sun, the sky is light and it's daytime. Then we turn away from the Sun and its night.
Years and seasons
The Earth takes just over 365 days to move around the Sun once and end up back in the same position. This is the basis of our calendar year.
We divide the year into seasons. Many people think that some parts of the year are hotter because we're nearer to the Sun. But the real reason is that the Earth is wonky.
The central axis that goes through the poles is tilted at an angle of 23.5 degrees, so it's not at right angles to the way we're travelling. As we move around the Sun during the year, the amount of light each area of the planet receives varies in length.
Here's a description of how the seasons change in the northern hemisphere. (If you live in the southern hemisphere, then you need to reverse the seasons).
Summer
The day the north pole is nearest the Sun is called the 'summer solstice'. (You can see this from the picture on the right). Looking from Earth, the Sun reaches its highest point in the sky all year. This means it takes the most amount of time to cross the sky. So this is the longest day of the year. It’s called the 'summer solstice' and happens around 21 June. Astronomers call this the start of summer and after this date, days start getting shorter.
Autumn
As we continue our journey around the Sun, the north pole moves away from the Sun. The Sun rises lower in the sky so the days continue getting shorter. When the Sun is at its mid-point in the sky, we reach the 'autumn equinox', around 22 September. Day and night are both 12 hours long and it’s the beginning of autumn.
Winter
The day when the north pole is furthest from the Sun is called the 'winter
solstice'. The Sun crosses the sky at its lowest point all year. Therefore it crosses the sky in the quickest time so this is the shortest day of the year. Winter solstice happens around 22 December and marks the start of winter. From then on, the days start getting longer.
Spring
The Earth continues on its path and our north pole starts moving towards the Sun again. The Sun moves upwards in our skies and the days continue getting longer. Again, we reach a midpoint when day and night are both 12 hours long. This is called the 'vernal (or spring) equinox' and happens around 21 March.
Seasons Across The World
The further north or south you live in the world, the more pronounced the seasons are. For example, in the far north, Alaska has sunshine 24 hours a day during their summertime.
On The Equator
If you live near the equator, the Sun doesn't shift up and down in the sky as much. This means that the length of day temperature doesn't vary as much. So countries near the equator only have two seasons - rainy and dry.
Why Does The Earth Tilt?
No one knows why the Earth's axis is tilted by 23.5 degrees. Some astronomers think that about 5 billion years ago, when the Earth was still very young, it was struck by a Mars-sized planet. This colossal impact could have tipped our planet over. Whatever the reason, it's a good thing - if the Earth did not tilt, countries near the poles would be cold and dark all year round. If it tilted too much, the seasons would be very extreme – like on the planet Uranus. Here the winter lasts for 42 years in total darkness!
Some Cool Links
Click on any of the links below to find out lots of more cool stuff about the Earth, sun and moon.
Have fun!!!
Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
