Stars

1- Pleiades Star

• Known to pre-Islamic Arabs in the lunar and solar calendar; among Arabian Bedouins its rising signals the start of summer. In modern astronomy it is called the Seven Sisters or the Pleiades Cluster, an open star cluster in Taurus, one of the brightest and most famous open clusters, visible to the naked eye, consisting of hot blue stars formed about 100 million years ago from a molecular cloud.

2- Aldebaran

• A bright orange star located in the Taurus constellation, known to ancient Arabs in the lunar and solar calendar. Bedouins called it “the follower” because it follows the Pleiades. In modern astronomy, it is a giant star 65 light-years from Earth.

3- First Al-Jawza’

• Known to ancient Arabs as Al-Jawza’, a group of stars near Taurus; among Bedouins, its rising signals the onset of strong seasonal winds.

4- Second Al-Jawza’

• Known to ancient Arabs as Al-Jawza’, a group of stars near Taurus. Bedouins separated part of the constellation and called it “Second Al-Jawza’,” whose rising marks the continuation of the seasonal winds.

5- Al-Mirzam (Sirius)

• The brightest star in the sky, known to ancient Arabs as Al-Shi’ra Al-Yamaniyya; among Bedouins, it was called Al-Mirzam because it leads all stars in brightness. Its rising signals peak summer heat.

6- Al-Kalibayn (Canis Major Stars)

• Two small stars in the Canis Major constellation; among Bedouins, their rising is associated with increased humidity.

7- Suhail (Canopus)

• Known to ancient and modern Arabs; one of the most important stars to Bedouins in Arabia. Its rising signals the cooling of late-night temperatures.

Seasons

1- Al-Wasm (Rain Mark)

• Known to ancient Arabs as the rainy season; ‘Al-Wasm’ means the mark of rain on the ground.

2- Al-Murabba’aniya

• The start of the cold season lasting 40 days.

3- Al-Shabt (Midwinter)

• The Al-Shabt season is known among Arabs and ancient civilizations; among Arabian Bedouins it is a period of intense cold, with a designated week called ‘Al-Azraq’ (from ‘blue’), indicating severe cold.

4- Al-Aqareb (Scorpions Season)

• The Al-Aqareb season marks the end of winter, with warming weather towards the end, signaling the start of spring. It consists of three stars: the first is ‘Aqrab Al-Sam’ (poison scorpion) for its coldness, the second ‘Aqrab Al-Dam’ (blood scorpion) also for its cold, and the third ‘Aqrab Al-Dasam’ (fat scorpion) when livestock gain weight.

5- Al-Hameem

• Named Al-Hameem due to people’s feeling of warmth after the winter cold.

6- Al-Dhuraan

• The season following Al-Hameem, characterized by frequent storms (‘Sarayat’).

7- Al-Kannah

• Marks the beginning of the end of mild spring in Kuwait; lasts 39 days and is when the Pleiades star disappears.

8- Bard Al-Ajooz (Old Woman’s Cold)

• Also known as ‘Mawsim Al-Husoom’; days when one feels a return of cold after warm days.

9- Bard Bayaa’ Al-Khabel Aba’ata (Fool Who Sold His Cloak Cold)

• In Arabian Peninsula, refers to selling one’s cloak at winter’s end only to be surprised by the return of cold—hence ‘the fool who sold his cloak.’

10- Sarayat (Spring Storms)

• Sudden winds and thunderstorms during spring.

11- Disappearance of Pleiades

• The disappearance of the Pleiades star during the ‘Al-Kannah’ season.

12- Jamrat Al-Qayz (Peak of Heat)

• Refers to the period when summer temperatures reach their peak; known as the hottest days of the year.

1. Absorption Spectrum
   A spectrum that displays dark bands or lines caused by light energy being absorbed at specific points by a substance located between the light source and the instrument producing the spectrum.
2. Aeropause
   A region in the upper atmosphere that is extremely rarefied and incapable of supporting conventional aircraft.
3. Aerospace
   The entire expanse above Earth’s surface, including both the atmosphere and outer space.
4. Albedo
   The ratio of light reflected from an object to the total light incident upon it.
5. Alpha
   Denotes the brightest star in a given constellation.
6. Aphelion
   The point in the orbit of a comet or planet where it is farthest from the Sun.
7. Apogee
   The point in the elliptical orbit of a moon where it is farthest from the Earth.
8. Artificial Satellite
   A human-made object launched into space with sufficient speed and angle to enter orbit around the Earth or another celestial body.
9. Asteroid
   A small, irregularly shaped body that orbits the Sun, found mainly in the region between Mars and Jupiter.
10. Astronaut
    A pilot specifically selected and trained for space travel.
11. Astronomer
    A person engaged in the study of the positions, motions, sizes, and physical phenomena of celestial bodies.
12. Astronomical Unit
    The average distance between the Earth and the Sun, approximately 92,907,000 miles (149,500,000 kilometers).
13. Astronomy
    The study of celestial bodies; one of the oldest sciences.
14. Astrophysics
    The science of applying physical laws and principles to astronomical studies.
15. Aurora Australis
    A natural light display radiating from the southern polar region, believed to result from atmospheric electrical disturbances.
16. Aurora Borealis
    A natural light display radiating from the northern polar region, believed to result from atmospheric electrical disturbances.
17. Azimuth
    The arc of the horizon measured clockwise from a fixed point (north or south) to the vertical circle passing through the object.
18. Ballistic Missile
    An unmanned vehicle launched on a set trajectory that follows a ballistic path in its final stages due to gravity. Developed during World War II.
19. Binary Stars
    Two stars that orbit a common center of mass; also called double stars.
20. Bipropellant
    Rocket fuel consisting of two separate chemicals, one as fuel and one as oxidizer, fed into the combustion chamber separately.
21. Booster Rocket
    An auxiliary rocket used to launch a larger rocket. It delivers strong thrust for a short time.
22. Bright Nebula
    A cloud of dust and gas in space that shines by reflecting or emitting light from a nearby star.
23. Capsule
    A compartment for humans, animals, or instruments, attached to a propulsion unit such as a rocket.
24. Carbon Cycle
    A series of thermonuclear fusion reactions in which carbon-12 catalyzes the fusion of hydrogen into helium, releasing tremendous energy. Proposed by Hans Bethe to explain stellar energy.
25. Cassegrainian Reflector
    A reflecting telescope in which light reflects from a primary concave mirror to a secondary convex mirror placed at the opposite end of the telescope tube, then passes through a small hole in the center of the primary mirror to reach the eyepiece or camera.
    The Cassegrainian reflector is relatively compact and allows the observer to operate the telescope from the lower end.
26. Cassini’s Division
    The dark gap between Saturn’s two main rings, approximately 5,000 km wide.
27. Celestial Equator
    An imaginary circle on the celestial sphere, aligned with Earth’s equator, used by astronomers to locate celestial objects.
28. Celestial Mechanics
    A branch of astronomy that uses theoretical mechanics to study the motion of celestial bodies under gravitational forces. It allows precise prediction of celestial positions.
29. Celestial Pole
    Either of the two points where Earth’s axis, if extended, would intersect the celestial sphere. The celestial meridian passes through both celestial poles and the observer’s zenith.
30. Celestial Sphere
    An imaginary sphere surrounding Earth on which celestial bodies appear to be projected. It is divided by reference lines used to map positions in the sky. Its apparent rotation is due to Earth’s daily rotation.
31. Cepheid Variable
    A type of variable star whose brightness changes regularly. Astronomers use the relationship between their period and luminosity to measure distances in space.
32. Chromosphere
    The reddish glowing layer of gas in the Sun’s atmosphere, emitting hydrogen and other gases. Typically visible only during a total solar eclipse.
33. Clock Drive
    A mechanical device that rotates a telescope to follow a celestial object, compensating for Earth’s rotation. It’s essential for long-exposure astrophotography.
34. Closed Ecological System
    A self-sustaining life support system used in spacecraft that recycles carbon dioxide and waste into oxygen and food, often using photosynthesis.
35. Cluster
    A group of stars that are relatively close to each other compared to other stars. The Pleiades is one of the most famous star clusters, located in Taurus.
36. Coal Sack
    A dense cloud of dust and gas in space that absorbs starlight, appearing as a dark patch in the Milky Way. Prominent ones are seen near the Southern Cross and the Cygnus constellation.
37. Colliding Galaxies
    Two large groups of stars (galaxies) that overlap or pass through each other, though individual stars rarely collide due to vast distances.
38. Coma
    The glowing envelope of gas and dust surrounding the nucleus of a comet.
39. Comet
    A celestial object composed of a nucleus and a surrounding coma, usually with a tail. It travels in an elliptical orbit around the Sun. Its tail always points away from the Sun. Halley’s Comet is a well-known example.
40. Communications Satellite
    A satellite used to transmit radio and television signals, either by passive reflection or active amplification and retransmission. Telstar was the first to enable live transatlantic broadcasts.
41. Conjunction
    The alignment of two or more celestial bodies (e.g., the Sun and a planet) in a straight line as seen from Earth. If the planet is in front of the Sun, it’s an inferior conjunction; if behind, it’s a superior conjunction.
42. Constellation
    A visible grouping of stars named after animals, objects, or mythological figures. Astronomers define constellations as specific regions in the sky. Cassiopeia appears as a “W” in the northern sky.
43. Copernican System
    The 16th-century model proposed by Nicolaus Copernicus placing the Sun at the center of the solar system, with Earth rotating on its axis and revolving around it. Supported by observations from Tycho Brahe, Kepler, and Galileo.
44. Corona
    The Sun’s outermost atmosphere, seen as a pearly white halo during a total solar eclipse. Observations show it extends at least 11 million kilometers (7 million miles) from the Sun’s surface.
45. Cosmic Dust
    Extremely fine dust particles found in space that often obscure visibility of interstellar objects.
46. Cosmic Rays
    Radiation from outer space that bombards Earth’s atmosphere. Primary rays interact with atmospheric atoms, producing secondary rays. Spacecraft designs must account for their penetrating power.
47. Cosmology
    A branch of astronomy that studies the origin and evolution of the universe. Whipple’s cloud theory is one such model related to the solar system.
48. Counter Glow (Gegenschein)
    An elliptical glow on the ecliptic opposite the Sun, believed to be sunlight reflected off interplanetary particles. It is faint and best captured using wide-field photography.
49. Crab Nebula
    A gaseous cloud in the constellation Taurus shaped like a crab. It is the remnant of a massive stellar explosion observed by Chinese astronomers in 1054 AD. Appears as a faint star to the naked eye.
50. Crater
    A bowl-shaped depression on the surface of the Moon.
51. Crepe Ring
    The innermost and faintest ring of Saturn, almost transparent.
    Starlight may pass through the crepe ring.
52. Crescent
    A term for the Moon or a planet when less than half of it appears illuminated.
    The Moon appears as a crescent in the western sky at sunset between new moon and first quarter.