Which one of the following is a reason why astronomical distances are measured in light-years?
- ADistances among stellar bodies do not change.
- BGravity of stellar bodies does not change.
- CLight always travels in straight line.
- DSpeed of light is always same.Correct
Explanation
The reason astronomical distances are measured in light-years is primarily because the speed of light in a vacuum is a universal constant. Light travels at an incredibly high but finite speed (approximately 299,792,458 meters per second). Because of the immense distances involved in astronomy, using conventional units like kilometers or miles would result in unwieldy large numbers. A light-year, defined as the distance light travels in one Julian year, provides a convenient and comprehensible unit for these vast scales. The constancy of the speed of light makes this unit reliable and uniform across the universe, making it an ideal fundamental measure for cosmic distances.
Related questions
More UPSC Prelims practice from the same subject and topic.
- Prelims 2021GS1science-and-technology
Which one of the following is used in preparing a natural mosquito repellent?
- Prelims 2021GS1science-and-technology
In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following? 1. Area of the hole in the lid 2. Temperature of the flame 3. Weight of the lid Select the…
- Prelims 2021GS1science-and-technology
Consider the following : 1. Bacteria 2. Fungi 3. Virus Which of the above can be cultured in artificial/synthetic medium?
- Prelims 2021GS1science-and-technology
Water can dissolve more substances than any other liquid because
- Prelims 2021GS1science-and-technology
With reference to street-lighting, how do sodium lamps differ from LED lamps? 1. Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps. 2. As street-lights, sodium lamps …
- Prelims 2021GS1science-and-technology
The term 'ACE2' is talked about in the context of