Physics

Law of Universal Gravitation

Describes the gravitational attraction between objects with mass, formulated by Newton as an inverse-square law.

2. Gravitation:

The force of attraction between masses, responsible for phenomena like planetary orbits and falling objects on Earth.

3. Four fundamental forces in nature:

Gravitational, electromagnetic, weak nuclear, and strong nuclear forces, governing interactions at the fundamental level.

4. Newton's Law of Universal Gravitation & Laws:

States that every particle attracts every other particle with a force proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

5. Einstein's General Theory of Relativity:

A theory of gravitation that explains gravity as the curvature of spacetime caused by mass-energy.

6. Kepler's Laws:

1. Kepler's First Law (Law of Ellipses): The orbit of a planet around the Sun is an ellipse with the Sun at one of the two foci.

2. Kepler's Second Law (Law of Equal Areas): A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. This means that a planet moves faster when it is closer to the Sun and slower when it is farther away.

3. Kepler's Third Law (Law of Harmonies): The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit. In simpler terms, this law relates the time it takes for a planet to orbit the Sun (its orbital period) to its distance from the Sun.

7. Elliptical Orbits:

Paths followed by celestial bodies under the influence of gravitational forces, characterized by elongated shapes.

8. Orbital Periods:

Time taken by a celestial body to complete one orbit around another, often related to the semi-major axis of the orbit.

9. Semi-Major Axes:

Half of the longest diameter of an elliptical orbit, determining its size and shape.

10. Velocity:

Rate of change of position with respect to time, indicating the speed and direction of an object's motion.

11. Acceleration:

Rate of change of velocity with respect to time, indicating how quickly an object's velocity is changing.

12. Gravitational acceleration (g):

Acceleration due to gravity, usually denoted by 'g' and measured in meters per second squared (m/s²).

13. Astronomical Unit (AU):

Average distance between the Earth and the Sun, used as a standard unit of distance in astronomy.

14. Inertia:

Tendency of an object to resist changes in its state of motion.

15. Centripetal Force:

Force directed toward the center of a circular path, required to keep an object moving in uniform circular motion.

16. Weight:

Force exerted on an object due to gravity.

17. Mass:

Measure of the amount of matter in an object, determining its inertia and gravitational interaction.

18. Theory of Relativity:

Physical theories formulated by Einstein, including special relativity (concerning non-accelerating observers) and general relativity (gravity).

19. Order of Planets:

Sequence of planets in the solar system, typically listed as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

20. Astronomical Observatories:

Facilities equipped for observing celestial objects and phenomena, often housing telescopes and other instruments.

21. Electromagnetic Spectrum:

Range of all possible frequencies of electromagnetic radiation, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

22. Photons:

Elementary particles of light, carriers of electromagnetic radiation.

23. Spectroscopy:

Study of the interaction between matter and electromagnetic radiation, often used to analyze the composition and properties of celestial objects.

24. Nebula:

Interstellar cloud of dust, hydrogen, helium, and other gases, where stars are born.

25. Stages in the Life of a Star:

Sequence of stages a star undergoes from its formation to its eventual demise, including protostar, main sequence, red giant, planetary nebula, and white dwarf or supernova.

26. Speed of Light:

Constant speed at which light travels in a vacuum, approximately 299,792 kilometers per second (km/s).

27. Frequency, Wavelength, and Energy Relations:

Frequency and wavelength are inversely related in electromagnetic radiation, while energy is directly proportional to frequency (E = hf, where E is energy, h is Planck's constant, and f is frequency).

28. Light Years:

Unit of astronomical distance equal to the distance light travels in one year, approximately 9.461 trillion kilometers.

29. Hubble's Discoveries:

Observations by Edwin Hubble, including the expansion of the universe and the relationship between recessional velocity and distance of galaxies.

30. Universe Expansion, Dark Matter & Energy, The Big Bang Theory:

Concepts describing the large-scale structure and evolution of the universe, including its expansion from a hot, dense state (the Big Bang), the presence of unknown substances like dark matter and dark energy, and the ongoing expansion of the cosmos.

Velocity of reccession

Recessional velocity refers to the speed at which an object is moving away from an observer. In cosmology, it's often used to describe the rate at which galaxies are moving away from us due to the expansion of the universe. This concept is a key component of Hubble's Law, which describes the relationship between the recessional velocity of distant galaxies and their distance from Earth.

Doppler’s effect

Doppler effect is the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. It's commonly experienced with sound waves, like the change in pitch of a siren as it passes by. In astronomy, it's crucial for determining the motion of celestial objects, such as the redshift of galaxies due to the expansion of the universe.

Sun’s status

Surface: 5600 kelvin

Core: 15 million Celsius

4,6 billion years