# Questions and Answers to Them in Astronomy

why does the tilt of Earth’s axis relative to its orbit cause the seasons as Earth revolves around the Sun?

13. Why does the tilt of Earth’s axis relative to its orbit cause the seasons as Earth revolves around the Sun?

Answer: This is because some parts seem to be close to the sun in comparison with others.
21. What is the line of nodes, and how is it related to solar and lunar eclipses?

Answer: The orbit of the moon is tilted about five degrees from the plane of the ecliptic. The line which is created by the ecliptics intersection as well as the plane of the Moon’s orbit is referred to as the line of nodes. When the Moon is on the nodes line during the new phase, a solar eclipse occurs. When it is on the nodes line during a full phase, (fully illuminated) the result is a lunar eclipse.
27. At which phase(s) of the Moon does a solar eclipse occur? A lunar eclipse?

Answer: A solar eclipse occur during the new moon whereas a lunar eclipse at the full moon.
10. What are Kepler’s three laws? ‘Why are they important?

Answer: Kepler came up with three laws of planetary motion. This was from Tycho Brahe’s observational data. One of the law states that the planets move around the Sun. It does move in elliptical paths with the Sun having one focus. The second law states that a line which joins a planet and the Sun has to sweep out equal areas in equal times. The effect of second law is that planets tend to move faster. This is determined by the closeness they have to the Sun. They slow down as they move farther from the sun. The third law states that the square of a planet’s sidereal period around the Sun must be directly proportional to the cube of the length of its orbit’s semi major axis. This law insinuates that for any pair of the planets, the one with a greater average distance from the Sun has got the longer year. The three laws are significant because they summarize how planets orbit the Sun as well as how moons orbit planets.

14. Why was the discovery of Neptune a major confirmation of Newton’s universal law of gravitation?

Answer: The Neptune existence and location were correctly predicted from Newton’s law of universal gravitation in advance of discovery of Neptune. Its presence was inferred by its effect of gravity on the Uranus orbit.
6. What are the three major functions of a telescope?

Answer: the instrument increases the light amount gathered. This makes objects brighter and dimmer objects visible), it also shows an increased object angular resolution it views. Hence, this enlarges the image.
12. Why can radio astronomers observe at any time of the day or night, whereas optical astronomers are mostly limited to observing at night?

Answer: Day and night refers to an ambient visible light in the sky. Daylight never interferes with radio waves which pass through the atmosphere of the earth. Visible light from stars as well as other astronomical objects are very dim to be seen during the day. Some human-made radio signals emitted at any time of the never interferes with radio astronomy.
5. What is Wien’s law? How could you use it to determine the temperature of a start surface?

Answer: Wien’s law is a mathematical relationship between the temperature of a blackbody and the dominant wave length. It states that the hotter the object, the shorter the peaks wavelength of its blackbody curve. This peak is the wavelength which, the body emits intensely. Since all the blackbodies with the same temperature possess the same blackbody curves, finding the wavelength at the peak of the continuous spectrum enables you to calculate the object’s surface temperature directly.

11. Explain how the spectrum of hydrogen is related to the structure of the hydrogen atom.

Answer: Electrons have only certain orbits which are around their nuclei. The allowed orbits, which are actually associated with discrete levels of energy, are different. This is with regard to all different types of atoms. The wavelength of an atom’s spectral line is determined by the difference in the orbits energies which its electrons transfer. The wave length can be either emitted or absorbed. When electrons descend in orbit, they emit photons. This creates emission spectra. When they go to higher orbits, they absorb photons which lead to the absorption spectra. Since all elements have allowed orbits with different levels of energy, the emission as well as the absorption spectra of each element, such as hydrogen, has a unique set of wavelengths.