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About Josh
Expertise
When I work through problems, I emphasize principles and key ideas which I believe are worth noting. I will try to answer questions in the following areas, but not at the advanced level. Algebra. Sequences & Series. Trigonometry. Functions & Graphs. Coordinate Geometry. Quadratic Polynomials. Exponentials & Logarithms. Basic Calculus. Probability, Permutations and Combinations. Mathematical Induction. Complex numbers. Physics problems.

Experience

Experience:
I have worked as a teaching assistant in college. My hope is that more people will share knowledge without boundary, give help without seeking recognition or monetary rewards.

Supplementary Website:
See a selection of past questions in my maths repository under "Question Archive"

Education Credentials:
Bachelor degree in Engineering Science.

"Everyone struggles with something."

You are here: Experts > Science > Math for Kids > Basic Math > supernova 1054 a.d. chinese

Basic Math - supernova 1054 a.d. chinese

Expert: Josh - 10/14/2009

Question
In a.d. 1054, chinese astronomers observed the light from a supernova in the night sky. This supernova was incredibly powerful origin of what is now Crab Nebula.
Using the velocity of light,devose and executea strategy for finding out when the supernova actually occured, relative to when the chinese astronomers saw the explosion. Show work and please explain.

Answer
Hi Edward,

Here is a simplistic view of the problem, assuming that Crab Nebula is stationary relative to the astronomers on Earth when the event took place. That is, we view this as a basic high school physics problem and ignore any special relativity effects.

Suppose the light takes time "t" to travel a distance "D" to reach Earth. We need to find out the approximate distance of the supernova from the Earth using astronomical data.

Earth <-----------D------------< Supernova
1054 A.D. 1054 A.D. -t

Since the speed of light C=D/t, as a rough estimate, the explosion of light must have taken place some interval "t" before 1054 A.D. Note: make sure you use the right units in your calculation. Distance is typically expressed in light years, so perhaps you may need to convert this to meter or kilometer. Speed is often measured in meter/sec. You have to reconcile the differences between these units to obtain the proper answer.

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