All stars begin their lives as clouds of gas and dust which are called nebulae. The particles in a nebula start to attract, so their combined mass increases. Therefore, they have more gravity which pulls in even more particles. Eventually, there will be enough particles under intense heat and pressure in the center core and nuclear fusion can occur. The star ignites and becomes a fully functioning star.
The image, below, shows the life cycles of different types of stars.
Depending on the amount of material in the nebula, an average star (like the Sun) or a supermassive star is formed. As the star burns through its fuel, it loses mass; therefore, it has less gravity and its size increases. An average star turns into a red giant. As it continues burning fuel, the red giant becomes very large. Then, the outer layers are blown off creating a planetary nebula and the inner core of the star remains, called a white dwarf star.
A supermassive star turns into a super red giant. These stars have more mass so they burn through their fuel more quickly, therefore losing gravity and becoming extremely large. Eventually, the super red giant will run out of fuel, collapse in on itself, and create a giant explosion called a supernova. From there, the star can either form a black hole or an extremely compact neutron star.
Interesting Fact: We Are Made of Stardust
Nuclear fusion in stars begins with hydrogen atoms which fuse together to make helium. Eventually, the reactions increase and atoms continue fusing into different elements; stars can fuse all of the elements up to iron on the periodic table.
When the dust and debris from a star is blown away in a planetary nebula or supernova, all of these elements scatter into space where they will become the basis for all new stars and matter in the universe. Therefore, we are made of stardust.
Meteors, Meteorites, Craters, and Comets
Many of you have seen a streak in the night sky, often referring to it as a “shooting star”. But what is it and how does it all work? Well, in the simplest terms, there are a bunch of rocks floating around in space. Many of them come from the asteroid belt, betweem Mars and Jupiter, that scientists believe was an area that never formed into a planet. Some folks believe there was a planet there that blew up but the evidence doesn’t support that theory. However, within the asteroid belt, collisions happen which eject material out of the belt and toward earth. These “rocks” are known as meteoroids. As they enter the earth’s atmosphere they typically burn up, looking like a shooting star, but now known as a meteor. If it is large enough to survive and reach the earth, it can leave behind a crater and it’s name also now changes to meteorite. Meanwhile, asteroids and comets are both known to orbit the earth. However, a comet has a “tail” as the gases within it’s composition heat up and are released. Haley’s comet is one of the most famous comets, having been recorded since at least 240 BCE and with a retun date predicted for mid-year 2061.
🌠 Meteors
Definition: A meteor is the streak of light we see when a meteoroid (a small rock from space) enters Earth’s atmosphere and burns up due to friction.
Key Concepts:
Meteors are often called “shooting stars,” though they are not stars.
If a meteoroid survives its journey and lands on Earth, it’s called a meteorite.
Meteor showers occur when Earth passes through debris left by a comet.
☄️ Comets
Definition: Comets are icy bodies that orbit the Sun. When they get close to the Sun, they heat up and release gas and dust, forming a glowing coma and often a tail.
Key Concepts:
Comets are made of ice, dust, and rocky material.
Their tails always point away from the Sun due to solar wind.
Famous example: Halley’s Comet, visible from Earth about every 76 years.
🪨 Asteroids
Definition: Asteroids are rocky objects that orbit the Sun, mostly found in the asteroid belt between Mars and Jupiter.
Key Concepts:
They vary in size from tiny rocks to hundreds of kilometers wide.
Unlike comets, asteroids don’t have tails because they don’t release gas.
Some asteroids have moons or even rings.
🌠 What Is a Shooting Star?
A shooting star is the bright streak of light we see in the sky when a meteoroid (a small piece of rock or metal from space) enters Earth’s atmosphere.
As it travels through the atmosphere, it burns up due to friction, creating the glowing trail we call a shooting star.
The Asteroid Belt
The asteroid belt is located between the orbits of the planets Mars and Jupiter. In this specific region, you will find the vast majority of asteroids. These asteroids are also known as minor planets or planetoids. Some major asteroids in the asteroid belt are Ceres, Vesta, Pallas and Hygiea.
These four asteroids comprise around half of the mass of the entire asteroid belt. Ceres is the only asteroid which is categorized as a dwarf planet as it is the largest asteroid in the inner solar system.
Facts you didn’t know: –
These small solar system bodies also orbit the Sun. These bodies are irregularly shaped and are made up of rock and metal.
The thickness of the asteroid belt is about 1 astronomical unit (AU).
Asteroids vary in size. Some of them are as small as pebbles and some of them have a diameter more than 400 km.
The entire belt is made up of billions of bodies but only 7,000 of them have received an official name designation.
The average distance between two asteroids is 600,000 miles.
Some asteroids are solid objects and some of them are more like piles of rubble loosely clung together.
According to scientists, asteroids are leftovers of the early solar system.
Some asteroids can be moved out of the belt and sent to the outer solar system because of gravitational influences.
Asteroids contain a high volume of resources that are highly valued on earth like: – nickel, iron and titanium.
The average surface temperature of an asteroid is -73°C.
Galaxies
A galaxy is a collection of billions of stars, gas, and dust held together by gravity in space. Using the Hubble Space Telescope, scientists can take images of space. In one small area, called the eXtreme Deep Field or XDF (image below) each of the bright spots is an entire galaxy–there are 5,550 galaxies within the image. There are probably 100 hundred billion galaxies in the entire universe.
A galaxy is a collection of billions of stars, gas, and dust held together by gravity in space. Our solar system is located in the Milky Way Galaxy. As seen in the image, below, it got its name because it appears as a milky band of light in the sky.
As seen in the image, below, the Milky Way is a large spiral-shaped galaxy which contains hundreds of billions of stars. At the center of the Milky Way is a supermassive black hole named Sagittarius A which has a mass of 4 million suns. Our Sun, Earth, and all the planets are located halfway between the center and the outer edge on a small partial arm called the Orion Spur.
Spiral shape of the Milky Way Galaxy. Our solar system is located on the Orion Spur. “The Milky Way Galaxy” by NASA/JPL-Caltech/R. Hurt
As seen in the image, below, there are 3 shapes of galaxies: spiral, elliptical, and irregular. Our galaxy, the Milky Way, is a spiral galaxy. Most galaxies have a supermassive black hole at the center which has an extremely strong gravitational pull that holds the entire galaxy together.
A black hole is an area in space with extremely strong gravity from which no light can escape. Thus, the area appears black. At the end of its lifecycle, a supermassive star collapses in on itself which causes a huge explosion called a supernova; this results in the formation of a black hole.
Seen below, scientists captured the first image of a black hole in 2019 using powerful telescopes.
Since black holes trap all light inside, the dark spot in the center of the image is the black hole’s shadow surrounded by a ring of glowing gas in space. Based on this image, scientists were able to determine that the this black hole’s mass is 6.5 billion times larger than the mass of our Sun.
Interesting Fact
Katie Bouman, a female graduate student at MIT, led the creation of the computer algorithm that made it possible to get this first image of a black hole.
For more explanation of black holes, watch the following video.
Inner planets: Mercury, Venus, Earth, Mars – small, rocky, few moons.
Outer planets: Jupiter, Saturn, Uranus, Neptune – large, gaseous, many moons and rings.
Our solar system consists of a total of eight planets including earth. All of them orbit the Sun. These planets are divided in to two groups, Inner and Outer planets. These two types are decided on the basis of the planet’s position with respect to the Sun.
Mercury, Venus, Mars and Earth are inner planets as they are closest to the Sun and Neptune, Saturn, Jupiter and Uranus are outer planets.
Inner planets are also known as terrestrial planets and outer planets are known as gas giants. Mercury is the closest and Neptune is the furthest planet.
Inner Planets:
Mercury: – Mercury is the smallest of the four terrestrial or Inner planets with a diameter of 4,878 km. This planet does not have any moons. Mercury has a thin atmosphere that contains oxygen, hydrogen, helium, sodium and potassium.
Venus: – This planet was once considered a twin planet to earth. But later scientists discovered that the surface of this planet has a lead-melting temperature of 480°C. Venus has no moons or rings.
Mars: – This planet shows signs of liquid water flowing on its surface in the past. Atmosphere of Mars contains nitrogen, argon and carbon dioxide. This planet has two moons, Phobos and Deimos.
Earth: – It is the largest of all the inner planets. The diameter of our planet is 12,756 km. It is the only planet with life. Our planet has one moon and does not have any rings. Earth has an atmosphere that contains nitrogen and oxygen.
Outer Planets: –
Neptune: – This planet has six rings and 13 confirmed moons. The atmosphere of Neptune is made up of hydrogen, methane and helium. It is smallest of all the outer planets.
Saturn: – This planet has 7 known rings and 53 known moons. This planet is mostly made up of hydrogen and helium and has an atmosphere that is somewhat similar to Jupiter’s.
Jupiter: – It is the largest of all the outer planets. It is visible with the naked eye. This planet has 50 known moons.
Uranus: – Uranus has 27 moons and has an atmosphere that is mostly made up of helium, methane and hydrogen.
NGSS
Performance Expectations
5-ESS1-1.
Support an argument thatdifferences in the apparent brightness of the sun compared to other stars is due totheir relative distancesfrom the Earth.[Assessment Boundary: Assessment is limited to relative distances, not sizes, of stars. Assessment does not include other factors that affect apparent brightness (such as stellar masses, age, stage).]
MS-ESS1-2.
Develop and use a model to describethe role of gravity in the motions within galaxies and thesolar system. [Clarification Statement: Emphasis for the model is on gravity as the force that holds together the solar system and Milky Way galaxy and controls orbital motions within them. Examples of models can be physical (such as the analogy of distance along a football field or computer visualizations of elliptical orbits) or conceptual (such as mathematical proportions relative to the size of familiar objects such as students’ school or state).] [Assessment Boundary: Assessment does not include Kepler’s Laws of orbital motion or the apparent retrograde motion of the planets as viewed from Earth.]
MS-ESS1-3.
Analyze and interpret data to determinescale propertiesof objects in the solar system.[Clarification Statement: Emphasis is on the analysis of data from Earth-based instruments, space-based telescopes, and spacecraft to determine similarities and differences among solar system objects. Examples of scale properties include the sizes of an object’s layers (such as crust and atmosphere), surface features (such as volcanoes), and orbital radius. Examples of data include statistical information, drawings and photographs, and models.] [Assessment Boundary: Assessment does not include recalling facts about properties of the planets and other solar system bodies.]
The process by which stars get their energy. Atoms fuse together creating a nuclear reaction which releases energy in the form of heat and light in the star.
Phase in a star's life cycle where it greatly increases in size as it burns fuel through nuclear fusion.
The giant explosion of a supermassive star at the end of its life cycle.
An area in space with extremely strong gravity from which no light can escape.
A collection of billions of stars, gas, and dust held together by gravity in space.
Our Sun and all of the planets and other bodies in space (comets, asteroids, meteoroids) that orbit around the Sun in the plane of the ecliptic.
