Our solar system
What kind of star is the Sun?
An average sized main sequence star fusing hydrogen to helium
What is an HR diagram?
Used to compare stars by brightness (luminosity or absolute magnitude) and their surface temperature or colour.
What are the stages in life cycle of a star like the Sun?
Stellar nebula --> Main Sequence --> Red Giant --> Planetary nebula --> White Dwarf --> Black dwarf
What is a planet?
A planet is a celestial body that orbits a star, is massive enough to be rounded by its own gravity, and has "cleared the neighborhood" around its orbit of dust, asteroids and gases.
What was the first human made satellite in space?
Sputnik
What is the Milky way?
The name of our galaxy
Where are high mass stars located on an HR diagram?
High-mass stars are found in the upper-left corner of the main sequence. Low mass at the bottom right
What happens in the core of a Main sequence star to become a Red Giant?
Fusion of hydrogen stops, gravity takes over and the core contracts and heats up. Nuclear fusion of helium to carbon and oxygen to begins in the core and and the outer layers expand into a Red giant.
What are the four rocky or terrestrial planets?
Mercury, Venus, Earth and Mars
Where is New Zealand are satellites launch?
Māhia Penisula near Gisbourne by Rocket Lab
What is Pluto now?
A dwarf planet that used to be the 9th planet in our solar system
Why are brown dwarf stars like Gliese 229B not on an HR diagram?
They do not have sufficient mass to sustain stable hydrogen fusion to helium in their cores.
What is a supernova?
It is a powerful and luminous explosion of a massive star, marking its final evolutionary stages into a neutron star or black hole
What is a planetary disk?
A planetary disk is a rotating disk of gas and dust that surrounds a young star, forming the birthplace of planets.
What is the difference between a star and a planet?
Stars generate their own light and heat through nuclear fusion, while planets do not, instead reflecting light from their host star.
What role does gravity play in the solar system?
The Sun's gravitational pull keeps the planets, moons asteroids and comets in orbit around it.
Why are white dwarfs and the bottom left of the HR diagram?
They have a low luminosity but have a high surface temperature. This is because they are very small, the size of the Earth, which means they have a small surface area from which to radiate light.
They are very hot, dense core remnants of low mass stars that have exhausted their nuclear fuel.
What is meant by a stellar nebula?
A vast, swirling cloud of hydrogen gas and dust where new stars are born.
Gravity pulls denser pockets within the cloud together, causing them to collapse, heat up, and eventually ignite nuclear fusion, marking the birth of a new star.
How does the of accretion form planets?
Dust and gas particles gradually collide, stick together, and build up into larger and larger clumps over millions of years.
Once the clumps are about 1 km wide they have their own gravity that pulls more material into a spherical planet shape
What is the evidence for the moon being formed from a collision with another planet?
Analysis of the Earth and moon rocks are very similar.
Why do all the planets orbit the Sun in the same direction?
Due to the conservation of angular momentum from the spinning stellar nebula that formed our solar system. Planets inherited this orbit direction from the stellar nebula spin they originated from.
How does a Supergiant star compare to a main sequence star on the HR diagram?
Supergiants have much greater surface area and lower temperature and luminosity compared to main sequence stars .
What is the role of gravity in a stars formation?
Gravity within these clouds of dust and gas cause particles to be weakly attracted. As the cloud collapses under its own weight, the material gets compressed into smaller, denser clumps. Gravity continues to compress the core, raising the temperature to 15 million Kelvin and nuclear fusion starts.
How was Neptune's moon Triton most likely formed?
An Asteroid that has been captured by Neptune's gravitational pull
Why can Jupiter not become a star?
Why can Jupiter not become a star?
Jupiter has hydrogen and helium but cannot become a star because of its low mass. If it were 80 times more massive, it could well become a star.