St. Joseph Astronomy Olympiad 2013

ST. JOSEPH ASTRONOMY OLYMPIAD

2013

Total Marks: 50

Short Questions 1. Phobos and Deimos are moons that orbit which planet? A: Mars. 2. In what year did Neil Armstrong make his historic walk on the moon? A: 1969. 3. On what planet does a ‘year’ last only 88 days? A: Mercury. 4. The Asteroids Belt is between the orbits of which two planets? A: Mars and Jupiter. 5. Which planets are never visible at midnight? A: Mercury and Venus. 6. What is the star nearest to the sun? A: Alpha Centauri (Proxima Centauri). 7. Which planet seems to be turned on its side with an axis tilt of 98 degrees? A: Uranus. 8. Name of the brightest star in the sky? A: Sirius. 9. Name the Astronomer who discovered that Mars orbits the sun in an Elliptical Orbit? A: KEPLER. 10. What are Schmidt, Cassegrainian and Galilean examples of? A: TELESCOPES. 11. Who discovered that Universe is expanding? A: Edwin Hubble. 12. The full form of NASA? A: National Aeronautics and Space Administration. 13. The Comet known as Halley’s Comet has an average period of how many years? A: 76 years. 14. 95% of the Martian Atmosphere At mosphere is composed of which chemical substance? A: Carbon Dioxide. 15. Callisto and Ganymede are moons that orbit which planet? A: Jupiter. 16. One of the largest volcanoes in our Solar System is named Olympus Mons. Name the planet which has the volcano? A: Mars. 17. Which unlucky Apollo Lunar Landing was cancelled after an Oxygen Tank exploded? A: Apollo 13. 18. Which ‘Planet’ is usually the Brightest in the sky ? A: Venus. 19. The study of the Origin and Evolution of the Universe is known as ? A: Cosmology. 20. He completed his graduation from Cambridge University and was a Professor of Chittagong University. Name of the famous Bangladeshi Cosmologist who recently died? A: J N Islam (Jamal Nazrul Islam)

ST. JOSEPH ASTRONOMY OLYMPIAD

2013

Observational Astronomy Name of the Constellations these starts belong to: 1. Vega Answer: LYRA 2. Rigel Answer: Orion 3. Aldebaran Answer: Taurus 4. Sirius Answer: Canis Major 5. Polaris Answer: Ursa Minor

General Astrophysics Astronomical Data

 

Radius of Earth, Mass of Earth,

= 6.37 × 106

= 5.98 × 1024

Wien’s Constant = 0.00289mK

 

.

1 pc = 3.26 ly

.

Gravitational Constant, G =

−

6.67× 10

11

 − 2

2

1. Using the fact that the t he Gravitational acceleration, acceleration, g = 9.8 find the average average density of the Earth. (Mark: 5)

−

2

at the Earth’s surface,

Solution: As Earth is Spherical, Spherical, the volume of the Earth is

    =

Or, Or,

∴

Density of Earth,

    =

=



4

3

3

=

4 3



3

(6. (6.37 × 106 )

= 1.083 × 1021 m3

5.98×1024 1.083×10 21

 ≈ −  3

5522

3

(Answer)

ST. JOSEPH ASTRONOMY OLYMPIAD

2013

−



2. Given the strongest emitted wavelength, λ  = 5 × 10 7 . Find the surface temperature of the Sun. (Hint: Use Wien’s Displacement Law)  (Mark: 5)



Solution: Wien’s Displacement Law, λ 

Or, T = Or, T =

T = 0.00 .00289 289

  − 

0.00289 0.00289



λ 

0.00289 0.00289

5×10 7

Or, T = 5780 K 5800 (

≈   

)

3. Calculate the Escape Velocity ( ) from the Earth for a 5000-kg spacecraft, and determine the kinetic energy it must have at the Earth’s surface in order to escape the Earth’s Gravitational Field. (Mark: 10) Solution: The escape velocity velocity from the surface of Earth,

      −  −  2

=

2 6.67×10 11

=

2

6.37×10 6

= 1.12 × 104 The kinetic energy of the spacecraft is,

1

1

2

2

=

1 2



−

    =

2 (5.98×10 24

5000

(1.1 (1.12 2 × 104

−

1 2

)

= 3.14× 1011 J (Answer) 4. The sun’s nearest -neighbor -neighbor is Proxima Centauri, 4.2 ly distant. How far is this in Parsecs? (Mark: 5) Solution: We Know,

3.26

  =1

∴   ∴   1

4.2

=

1

3.26

=

1×4.2 3.26

= 1.29 .29

 ≈   1.3

 (

)

)