the Universe and its forces
2nd term Science 2nd ESO
index
1. The Solar System
2. The Sky we look at
3. Models of the Universe
4. Kepler's Laws
5. The Force that moves the Universe: Gravity
1.- the solar system
What do you remember of the solar system?
the sun
The Sun a quite small star; it is G-type main-sequence star, in other words a yellow dwarf. It Consists mainly of two gases: hydrogen and helium. Hydrogen Fusion forming helium.
The inner planets
The four planets closer to the Sun: Mercury, Venus, Earth and Mars Small size. Rocky planets: the crust and mantle are made of rock, the core is metallic
the asteroid belt
It is made up of many solid, irregularly shaped bodies, of many sizes but much smaller than planets.
CEres
Ceres is a dwarf planet that can be found in the asteroid belt, the biggest object in it. it was discovered in 1801.
The outer planets
The four planets farther to the Sun: Jupiter, saturn, Uranus, Neptune Gas Giants, the consist mainly of gases
Jupiter's Moons
Io, Europa, Ganymede, Callisto. They can be seen easily from Earth, they were discovered by Galileo, Galilean Moons.
saturn's Moons
Titan the second biggest satellite in the Solar System. it has dense atmosphere.
uranus' moons
The names of these satellites are chosen from characters in the works of the English writers William Shakespeare and Alexander Pope.
kuiper belt
It is a disc in the outer Solar System, similar to the Asteroid Belt, but much bigger (from 30 AU to 50 AU from the Sun). it consists mainly of small bodies and frozen volatiles, such as methane, ammonia and water.
dwarf planets in the kuiper's belt
haumea
Makemake
Pluto
eris
oort cloud
first described in 1950. surround the Sun at distances ranging from 2,000 to 200,000 au (0.03 to 3.2 light-years). Many comets of the solar system are thought to come from it.
The solar system
TODAY'S TASK:
Make your own drawing of the solar system. As complete as you can do it!
2.- the sky we look at
What can we see when we look at the night sky?
What can we see when we look at the night sky?
What can we see when we look at the night sky?
What can we see when we look at the night sky?
Celestials bodies in movement
we can notice not only a daily movement, but a annual one: not all the constellations are visible during the whole year.
How is the science that studies the universe called?
Astrology
Astronomy
How is the science that studies the universe called?
Astronomy
Astrology
It is considered a pseudoscience.The study of movement and position of celestial objects and their supposed influence on human lives
It is the scientific study of the universe, the space and celestial objects
Some questions
- Can we see the same constellations in summer and winter?
- Can we see the same constellations in the north hemisphere and the south hemisphere?
- Even in the same hemisphere, for instance the north, and the same time of the day, are the constellations in the same possition in the sky?
- Has the Astronomy and the Astrology something in common?
TODAY'S TASK:
Go to moodle and complete Constellation activity
3. Models of the universe
How do we study the Universe?
- The most common way of studying the universe is using telescopes:
- Refracting telescopes: they have lenses that bend the light. The first ones being invented.
- Reflecting telescopes: they have a wider tube with mirrors that reflect the light. The larger telescopes are of this type.
Models to explain the universe:Geocentric Model
Even before the telescope was invented, many classical scientists looked at the celestial bodies and developed different theories to explain their observations.
Aristotle, a Greek Scientist thought that the Universe was made up of 27 concentric spheres moving in circles around the Earth which was in the centre.
Models to explain the universe:Geocentric Model
The geocectric model of Aristotle could not explain the retrograde movement of the planets.
Ptolemy, also a Greek Scientist, described other Geocentric model that explained also the retrograde movement:
Acording to Ptolemy, the planets moved in spirals.They made small circles called EPICYCLES. These small circles moved around another big one circle called DEFERENT. Performing these movements it seems that sometimes the planet has a retrograd movement.
Geocentric model
So for over 1000 years, the Ptolemy Geocentric model was the one acepted
Models to explain the universe:Heliocentric Model
Other Greek philosphers as Heraclides Ponticus and Aristarchus of Samos proposed other model to explain the Universe in which the Sun was in the middle of it.
Until the XVI this theory was not taken too seriously. Nicolaus Copernicus developed this theory, which explain in a simpler way the movement of the Solar System. This theory places the Sun in the middle of the Universe and the planets revolve around it in elliptical orbits.
Heliocentric model
How does the Heliocentric model aswer the question of the retrograde motion of the planets?
Retrograde motion was simply a perspective effect caused when Earth passes a slower moving outer planet that makes the planet appear to be moving backwards relative to the background stars.Nothing is changing in the planet’s motion, and retrograde motion occurs as a natural perspective effect
Retrograde motion of planets
IT IS ONLY PERSPECTIVE!
TODAY'S TASK:
Go to moodle and complete "Models to explain the universe II" activity
4. Kepler's Laws
what is an orbit?
- The gravitationally curved path of a celestial object or spacecraft around a star, planet, or moon, resulting in a periodic elliptical revolution.
Kepler's Laws
Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun, published by Johannes Kepler between 1609 and 1619. These improved the heliocentric theory of Nicolaus Copernicus, replacing its circular orbits with epicycles with elliptical trajectories, and explaining how planetary velocities vary.
Kepler's 1st Law
The orbit of the planets is an ellipse with the Sun at one of the two foci of the ellipse. Perihelion is the closest part of the orbit to the sun, Aphelion is the furthest.
Kepler's 1st Law
The sun is in one of these foci, and the planets revolve around in an ellipse shape orbit. The area close to the sun: perihelion The area far from the Sun: aphelion
In mathematics, an ellipse is a plane curve surrounding two focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant.
Kepler's 1st Law
The area close to the sun: perihelion The area far from the Sun: aphelion
Helios: was the god of the Sun in Greek mythology. He was thought to ride a golden chariot which brought the Sun across the skies each day from the east to the west.
Kepler's 2nd Law
A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. That means that a planet moves faster when travels closer to the Sun what suggests the presence of a force that atracks the planets to the Sun (as Newton proved years later with his Gravity theory).
Kepler's 2nd Law: the Law of equal areas
The orbital radius and angular velocity of the planet in the elliptical orbit will vary. This is shown in the animation: the planet travels faster when closer to the Sun, then slower when farther from the Sun. Kepler's second law states that the blue sector has constant area.
A line segment joining a planet and the Sun sweeps out equal areas (blue areas) during equal intervals of time.
The planets move with a constant aeral velocity (also called sector velocity or sectorial velocity) is the rate at which area is swept out by a particle as it moves along a curve.
Kepler's 3rd Law
If the orbit is longer, more time will need the planet to complete it
Kepler's 3rd Law
If the orbit is longer, more time will need the planet to complete it The square of a planet's orbital period is proportional to the cube of the length of the semi-major axis of its orbit.
T = The time a planet needs to revolve around the SunR= The average distance from the planet the Sun. K= Kepler constat, that depends of the object around which other objects revolve
Kepler's 3rd Law
It takes longer time to revolve around the Sun if you are far away from it, not only becuse the distance is bigger, but also because you go slower !
Kepler's Law
- Orbits are elliptical
- Travelling closer to the Sun increases the speed
- The bigger the orbit (the further from the Sun) the longer time to revolve.
TODAY'S TASK:
Go to moodle and complete "Kepler's law" activity
5. The force that moves the Universe: Gravity
the force that moves the universe
We have already learnt that everything in the Universe is in movement, but WHY? .
Isaac Newton gave the answer to that question. He discovered that the movement of the planets in the Solar System is due to the atraction of the Sun to them.
the force that moves the universe
Newton concluded that the Sun exerts an attraction force on the planets that make them revolve around it. And exactly the same happens with the planets and their satellites (i. e. the Earth and the Moon).
Law of Universal Gravitation
Using Kepler's laws, Newton proposed the Law of Universal Gravitation: every particle attracts every other particle in the Universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
F1= Force exerted by the particle 1 F2= Force exerted by the particle 2 m1= particle 1 mass m2= particle 2 mass r= distance between particle 1 and 2 G= Gravitational constant
Law of Universal Gravitation
- Both particles exert this force on the other; they exert the force on each other.
- The object with bigger mass makes the other revolve around it (the small revolves around the bigger).
- The gravity is also responsible of the speed of the revolution:
- if it were slower the spining object would fall
- if it were faster it would scape: scape velocity to overcome the gravity force (for leaving the Earth: 11.2 km/s over 40 000 km/h)
Newton's apple vs Newton's Cannoball
Cannonball at slow speed It will simply fall back on Earth.
Cannonball at orbital speed at that altitude, it will go on circling around the Earth along a fixed circular orbit
Speed of cannonball at 0 m/s launched horizontally from a very tall mountain
Orbiting is falling
How does Superman fly?
Is he able to modify gravity?
Is he just jumping?
Neil DeGrasse Tyson's opinion
Gravity and Weight
The weight of an object is the force acting on the object due to gravity. It depends of the mass of the object and the gravity exerted on it (so it depends of the celestial body where the object is located).The unit of measurement for weight in the International System of Units (SI) is the newton.
Earth g= 9.8m/s2 Moon g= 1.6m/s2
Mars g= 3.7m/s2
Gravity and Weight
Earth g= 9.8m/s2 Mars g= 3.7m/s2 g value is 62'50% lower in Mars
WALKING ON THE mOON
Apollo Missions successfully landed on the Moon: Apollo 11 : Neil Armstrong and Buzz Aldrin Apollo 12 Apollo 14 Apollo 15 Apollo 16 Apollo 17 (3 people on each mission, 2 of them walking on the Moon): Only 12 people have stepped on another celestial body.
The Space Suit weight was 81Kg on Earth and 13.6Kg on the Moon
The Apollo 11 mision was the first to land on the Moon with its Lunar Module named Eagle.
gravity and tides
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth. Newton explained that tides are due to the gravity of the Moon and the Sun over Earth.
gravity and tides
The force of gravity rise the level of water in the two positions aligned with the Moon (high tide, pleamar), and low the level in the other two positions (low tide, bajamar). So every 24h there are two high tides an two low tides. When the Moon is aligned with the Sun, the gravity force of the two produced higher tides Spring tide (marea alta) Neap tide (marea baja)
The moon movement
ViDEO
To learn more about Gravity you can check this video titled: the gravity of the situation
TODAY'S TASK:
Go to moodle and complete "gravity" activity
The end!
Forces and movements of the Universe
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Transcript
the Universe and its forces
2nd term Science 2nd ESO
index
1. The Solar System
2. The Sky we look at
3. Models of the Universe
4. Kepler's Laws
5. The Force that moves the Universe: Gravity
1.- the solar system
What do you remember of the solar system?
the sun
The Sun a quite small star; it is G-type main-sequence star, in other words a yellow dwarf. It Consists mainly of two gases: hydrogen and helium. Hydrogen Fusion forming helium.
The inner planets
The four planets closer to the Sun: Mercury, Venus, Earth and Mars Small size. Rocky planets: the crust and mantle are made of rock, the core is metallic
the asteroid belt
It is made up of many solid, irregularly shaped bodies, of many sizes but much smaller than planets.
CEres
Ceres is a dwarf planet that can be found in the asteroid belt, the biggest object in it. it was discovered in 1801.
The outer planets
The four planets farther to the Sun: Jupiter, saturn, Uranus, Neptune Gas Giants, the consist mainly of gases
Jupiter's Moons
Io, Europa, Ganymede, Callisto. They can be seen easily from Earth, they were discovered by Galileo, Galilean Moons.
saturn's Moons
Titan the second biggest satellite in the Solar System. it has dense atmosphere.
uranus' moons
The names of these satellites are chosen from characters in the works of the English writers William Shakespeare and Alexander Pope.
kuiper belt
It is a disc in the outer Solar System, similar to the Asteroid Belt, but much bigger (from 30 AU to 50 AU from the Sun). it consists mainly of small bodies and frozen volatiles, such as methane, ammonia and water.
dwarf planets in the kuiper's belt
haumea
Makemake
Pluto
eris
oort cloud
first described in 1950. surround the Sun at distances ranging from 2,000 to 200,000 au (0.03 to 3.2 light-years). Many comets of the solar system are thought to come from it.
The solar system
TODAY'S TASK:
Make your own drawing of the solar system. As complete as you can do it!
2.- the sky we look at
What can we see when we look at the night sky?
What can we see when we look at the night sky?
What can we see when we look at the night sky?
What can we see when we look at the night sky?
Celestials bodies in movement
we can notice not only a daily movement, but a annual one: not all the constellations are visible during the whole year.
How is the science that studies the universe called?
Astrology
Astronomy
How is the science that studies the universe called?
Astronomy
Astrology
It is considered a pseudoscience.The study of movement and position of celestial objects and their supposed influence on human lives
It is the scientific study of the universe, the space and celestial objects
Some questions
TODAY'S TASK:
Go to moodle and complete Constellation activity
3. Models of the universe
How do we study the Universe?
Models to explain the universe:Geocentric Model
Even before the telescope was invented, many classical scientists looked at the celestial bodies and developed different theories to explain their observations.
Aristotle, a Greek Scientist thought that the Universe was made up of 27 concentric spheres moving in circles around the Earth which was in the centre.
Models to explain the universe:Geocentric Model
The geocectric model of Aristotle could not explain the retrograde movement of the planets.
Ptolemy, also a Greek Scientist, described other Geocentric model that explained also the retrograde movement:
Acording to Ptolemy, the planets moved in spirals.They made small circles called EPICYCLES. These small circles moved around another big one circle called DEFERENT. Performing these movements it seems that sometimes the planet has a retrograd movement.
Geocentric model
So for over 1000 years, the Ptolemy Geocentric model was the one acepted
Models to explain the universe:Heliocentric Model
Other Greek philosphers as Heraclides Ponticus and Aristarchus of Samos proposed other model to explain the Universe in which the Sun was in the middle of it.
Until the XVI this theory was not taken too seriously. Nicolaus Copernicus developed this theory, which explain in a simpler way the movement of the Solar System. This theory places the Sun in the middle of the Universe and the planets revolve around it in elliptical orbits.
Heliocentric model
How does the Heliocentric model aswer the question of the retrograde motion of the planets?
Retrograde motion was simply a perspective effect caused when Earth passes a slower moving outer planet that makes the planet appear to be moving backwards relative to the background stars.Nothing is changing in the planet’s motion, and retrograde motion occurs as a natural perspective effect
Retrograde motion of planets
IT IS ONLY PERSPECTIVE!
TODAY'S TASK:
Go to moodle and complete "Models to explain the universe II" activity
4. Kepler's Laws
what is an orbit?
Kepler's Laws
Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun, published by Johannes Kepler between 1609 and 1619. These improved the heliocentric theory of Nicolaus Copernicus, replacing its circular orbits with epicycles with elliptical trajectories, and explaining how planetary velocities vary.
Kepler's 1st Law
The orbit of the planets is an ellipse with the Sun at one of the two foci of the ellipse. Perihelion is the closest part of the orbit to the sun, Aphelion is the furthest.
Kepler's 1st Law
The sun is in one of these foci, and the planets revolve around in an ellipse shape orbit. The area close to the sun: perihelion The area far from the Sun: aphelion
In mathematics, an ellipse is a plane curve surrounding two focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant.
Kepler's 1st Law
The area close to the sun: perihelion The area far from the Sun: aphelion
Helios: was the god of the Sun in Greek mythology. He was thought to ride a golden chariot which brought the Sun across the skies each day from the east to the west.
Kepler's 2nd Law
A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. That means that a planet moves faster when travels closer to the Sun what suggests the presence of a force that atracks the planets to the Sun (as Newton proved years later with his Gravity theory).
Kepler's 2nd Law: the Law of equal areas
The orbital radius and angular velocity of the planet in the elliptical orbit will vary. This is shown in the animation: the planet travels faster when closer to the Sun, then slower when farther from the Sun. Kepler's second law states that the blue sector has constant area.
A line segment joining a planet and the Sun sweeps out equal areas (blue areas) during equal intervals of time. The planets move with a constant aeral velocity (also called sector velocity or sectorial velocity) is the rate at which area is swept out by a particle as it moves along a curve.
Kepler's 3rd Law
If the orbit is longer, more time will need the planet to complete it
Kepler's 3rd Law
If the orbit is longer, more time will need the planet to complete it The square of a planet's orbital period is proportional to the cube of the length of the semi-major axis of its orbit.
T = The time a planet needs to revolve around the SunR= The average distance from the planet the Sun. K= Kepler constat, that depends of the object around which other objects revolve
Kepler's 3rd Law
It takes longer time to revolve around the Sun if you are far away from it, not only becuse the distance is bigger, but also because you go slower !
Kepler's Law
TODAY'S TASK:
Go to moodle and complete "Kepler's law" activity
5. The force that moves the Universe: Gravity
the force that moves the universe
We have already learnt that everything in the Universe is in movement, but WHY? .
Isaac Newton gave the answer to that question. He discovered that the movement of the planets in the Solar System is due to the atraction of the Sun to them.
the force that moves the universe
Newton concluded that the Sun exerts an attraction force on the planets that make them revolve around it. And exactly the same happens with the planets and their satellites (i. e. the Earth and the Moon).
Law of Universal Gravitation
Using Kepler's laws, Newton proposed the Law of Universal Gravitation: every particle attracts every other particle in the Universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
F1= Force exerted by the particle 1 F2= Force exerted by the particle 2 m1= particle 1 mass m2= particle 2 mass r= distance between particle 1 and 2 G= Gravitational constant
Law of Universal Gravitation
Newton's apple vs Newton's Cannoball
Cannonball at slow speed It will simply fall back on Earth.
Cannonball at orbital speed at that altitude, it will go on circling around the Earth along a fixed circular orbit
Speed of cannonball at 0 m/s launched horizontally from a very tall mountain
Orbiting is falling
How does Superman fly?
Is he able to modify gravity?
Is he just jumping?
Neil DeGrasse Tyson's opinion
Gravity and Weight
The weight of an object is the force acting on the object due to gravity. It depends of the mass of the object and the gravity exerted on it (so it depends of the celestial body where the object is located).The unit of measurement for weight in the International System of Units (SI) is the newton.
Earth g= 9.8m/s2 Moon g= 1.6m/s2
Mars g= 3.7m/s2
Gravity and Weight
Earth g= 9.8m/s2 Mars g= 3.7m/s2 g value is 62'50% lower in Mars
WALKING ON THE mOON
Apollo Missions successfully landed on the Moon: Apollo 11 : Neil Armstrong and Buzz Aldrin Apollo 12 Apollo 14 Apollo 15 Apollo 16 Apollo 17 (3 people on each mission, 2 of them walking on the Moon): Only 12 people have stepped on another celestial body.
The Space Suit weight was 81Kg on Earth and 13.6Kg on the Moon
The Apollo 11 mision was the first to land on the Moon with its Lunar Module named Eagle.
gravity and tides
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth. Newton explained that tides are due to the gravity of the Moon and the Sun over Earth.
gravity and tides
The force of gravity rise the level of water in the two positions aligned with the Moon (high tide, pleamar), and low the level in the other two positions (low tide, bajamar). So every 24h there are two high tides an two low tides. When the Moon is aligned with the Sun, the gravity force of the two produced higher tides Spring tide (marea alta) Neap tide (marea baja)
The moon movement
ViDEO
To learn more about Gravity you can check this video titled: the gravity of the situation
TODAY'S TASK:
Go to moodle and complete "gravity" activity
The end!