Maharashtra State Board Class 7 Science In the world of Stars / Textbook Exercises and Extra Question and Answers.
Maharashtra State Board Class 7 Science In the world of Stars Key Points:
Star Formation: Stars are born from nebulae, which are clouds of hydrogen gas and dust particles. The force of gravity causes these clouds to contract and become dense, leading to energy generation processes and the formation of a star.
The Milky Way: Our solar system is a small part of the Milky Way galaxy, which contains numerous stars, some larger than our Sun, and some with their own planetary systems.
Celestial Sphere: The sky, as observed from Earth, can be visualized as a celestial sphere. This sphere includes the zenith (the point directly above an observer), nadir (the point directly below an observer), celestial poles (aligned with the Earth’s rotation axis), meridian (a great circle passing through celestial poles and zenith/nadir), celestial equator (an imaginary circle aligned with Earth’s equator), and the ecliptic (the apparent path of the Sun as seen from Earth).
Constellations: Constellations are groups of stars that appear to form patterns or figures. Western observers have identified 88 constellations, while there are 12 zodiac signs and 27 nakshatras in Indian astronomy.
Zodiac Signs: The ecliptic is divided into 12 equal parts, each covering 30 degrees and representing a zodiac sign, such as Aries, Taurus, and Pisces.
Nakshatras: Nakshatras are divisions of the celestial sphere based on the Moon’s position. Each nakshatra is about 13 degrees and 20 minutes in size and is named after its brightest star, called the yogatara.
The Great Bear (Saptarshi): This constellation, also known as the Great Bear in English, is a recognizable group of seven stars, resembling a kite. It is used for navigation and can lead to the Pole Star (Polaris).
Sharmishtha: Sharmishtha is another constellation that helps locate the Pole Star. It is shaped like the letter M, and the line bisecting the third and fourth stars in Sharmishtha points toward the Pole Star.
Mrug Nakshatra (Orion): Mrug Nakshatra, also known as Orion, is a constellation with very bright stars. It includes Vyadh or Sirius. It is prominent in the winter sky and serves as a reference point.
Vrushchik (Scorpio): The Scorpio constellation is located in the southern hemisphere and has Jyeshtha or Antares as its brightest star. It can be observed in the eastern sky after sunset in the third week of April.
Apparent Motion of the Sun: The Earth’s movement causes the apparent motion of the Sun and other celestial objects. This apparent motion is responsible for the changing position of the Sun relative to the zodiac signs and nakshatras.
Rising and Setting of Celestial Objects: The apparent motion of celestial objects, like the Sun, leads to their rising in the east and setting in the west. This apparent motion is an essential concept in astronomy and sky watching.
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