Dark galaxy

Context: Recently, Italian researchers have discovered a Dark Galaxy or Invisible Galaxy using Atacama Large Millimeter Array (ALMA).

About Dark Galaxy:

• It is termed invisible because the light emitted couldn’t be seen from the earth.
• The presence of the galaxy has been discovered using the gravitational lensing technique.

Gravitational lensing technique:

• It is an effect of Einstein’s theory of general relativity – simply put, mass bends light.
• The gravitational field of a massive object will extend far into space, and cause light rays passing close to that object to be bent and refocused somewhere else.
• It is discovered as compact.
• It is young and has interstellar dust.
• It is forming new stars at the rate of 1000 times the Milky Way.

Atacama Large Millimeter Array (ALMA):

• It is an international partnership of the European Southern Observatory (ESO), with U.S., Japan, Canada, Taiwan, Korea and Chile.
• It is the world’s largest ground-based facility for observations in the millimeter/submillimetre regime.
• It is a single telescope composed of 66 high precision antennas.
• It is located on the Chajnantor plateau, 5000 meters altitude in northern Chile.
• It allows scientists to unravel longstanding and important astronomical mysteries, in search of our Cosmic Origins.

Source:  Livescience

Previous Year Questions

Q.1) Which one of the following statements best reflects the idea behind the “Fractional Orbital Bombardment System” often talked about in media? (2022)

1. A hypersonic missile is launched into space to counter the asteroid approaching the Earth and explode it in space.
2. A spacecraft lands on another planet after making several orbital motions.
3. A missile is put into a stable orbit around the Earth and deorbits over a target on the Earth.
4. A spacecraft moves along a comet with the same speed and places a probe on its surface.

Q.2) If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth? (2022)

1. GPS and navigation systems could fail.
2. Tsunamis could occur at equatorial regions.
3. Power grids could be damaged.
4. Intense auroras could occur over much of the Earth.
5. Forest fires could take place over much of the planet.
6. Orbits of the satellites could be disturbed.
7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted.

Select the correct answer using the code given below:

1. 1, 2, 4 and 5 only
2. 2, 3, 5, 6 and 7 only
3. 1, 3, 4, 6 and 7 only
4. 1, 2, 3, 4, 5, 6 and 7