How large is our galaxy quizlet?
The Milky Way Galaxy is a spiral galaxy consisting of a thin disk about 100,000 light years in diameter with a central bulge and a spherical halo that surrounds the disk..
What is a point in the sky directly above your head called?
The point on the celestial sphere directly overhead for an observer is the zenith.
An imaginary arc passing through the celestial poles and through the zenith is called the observer's meridian..
What was the great contribution of Nicholas Copernicus?
Nicolaus Copernicus was a Polish astronomer who put forth the theory that the Sun is at rest near the center of the Universe, and that the Earth, spinning on its axis once daily, revolves annually around the Sun.
This is called the heliocentric, or Sun-centered, system..
Which of the following parts of the Sun is the hottest?
The centremost region of the Sun is known as the core; this is the region where Hydrogen turns into Helium through the nuclear fusion reaction.
With temperatures believed to be reaching more than 15 million degrees Celsius, the core is considered to be the hottest region of the Sun..
Why is a complete image formed even if half of a lens or mirror is blocked?
Suppose B is a sheet in black color in front of the lens and covers the upper half.
In this way, B blocks the upper half of image forming rays; but, the lower half of the image forming rays still can form the image.
Hence, the resulting image is still the whole object..
- What causes the Seasons? The tilt of Earth's rotational axis with respect to the plane of Earth's orbit causes the seasons.
- Why can't we see past the cosmological horizon? Beyond the cosmological horizon, we would be looking back to a time before the universe was born.
