🟡 درک مطلب در مورد astronomy
In the vast expanse of the universe, galaxies are the building blocks of the celestial realm. A galaxy is a massive collection of stars, gas, dust, and dark matter, bound together by gravity. Though countless galaxies exist, each one is unique in its structure, composition, and age. j
One distinctive type of galaxy that has captivated astronomers is the elliptical galaxy. Characterized by their oval shape, elliptical galaxies are composed primarily of older stars, with relatively little ongoing star formation. Their smooth and featureless appearance sets them apart from the more intricate spiral galaxies. Elliptical galaxies are known to be densely packed with stars, with some containing trillions of stars within their boundaries. j
The formation and evolution of galaxies are deeply intertwined phenomena. Scientists theorize that galaxies began to form shortly after the Big Bang, approximately 13.8 billion years ago. Through the forces of gravity, immense clouds of gas and dust collapsed, initiating the birth of stars and the formation of galaxies. Over time, galaxies have been subjected to various interactions and mergers, sculpting their shapes and redistributing their contents. These interactions, combined with the presence of dark matter, play a critical role in shaping the vast cosmic web we observe today. j
Q1. Which of the following best defines an elliptical galaxy? J
a) A galaxy composed primarily of young stars
b) A galaxy composed primarily of older stars
c) A galaxy composed primarily of gas and dust
d) A galaxy composed primarily of dark matter
Q2. How do elliptical galaxies differ from spiral galaxies? J
a) Elliptical galaxies have a smoother appearance
b) Elliptical galaxies have a higher star formation rate
c) Elliptical galaxies are less densely packed with stars
d) Elliptical galaxies have a rotating disk-like structure
Q3. What is thought to have initiated the formation of galaxies? J
a) Supernova explosions
b) The birth of stars
c) The presence of dark matter
d) The collapse of gas and dust clouds
Q4. How many years ago is estimated as the age of the universe according to the passage? J
a) 4.5 billion years
b) 10 billion years
c) 13.8 billion years
d) 30 billion years
Q5. What plays a critical role in shaping the cosmic web of galaxies? J
a) Supernovae
b) Solar winds
c) Dark matter
d) Gravity of black holes
