Astronomy/Time and Light

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Expert: Jesse Martinez - 1/24/2010


Question
Hi

I was wondering if you would be kind enough to help me.

I need a chart that shows how long Light takes to travel to Earth from various stars for instance

1.  Sun to Earth   8 mins

2.  Moon to Earth   

3.  Mars to Earth   

4.  Venus to Earth   

5.  Saturn to Earth   

6.  Jupiter to Earth   

7.  Neptune to Earth   

8.  Pluto to Earth   

9.  Mercury to Earth   

10. Uranus to Earth   

11. Center of the our Milky way to Earth

If you can assist in filling in the blanks I would really appreciate it

Many thanks

Answer
Hello Andrew. There are going to be problems answering this question. The distances between the planets you mentioned are continuously variable. They are not fixed distances, but instead have ranges of distances from each other. For example, the Earth to Venus distance can vary from between 42 million and 258 million kilometers or 0.28 to 1.72 AU apart depending on where each planet is in its orbit at a particular time. Any answer I give you today would be invalid tomorrow. To get the exact values on a given day, go to this site:  http://www.windows.ucar.edu/tour/link=/kids_space/distance.html

To figure out the time it takes for the light to reach earth, divide the distance that displays in A.U. (astronomical units) by the necessary factor. The site explains how. Convert to other units as needed. The time it takes light to reach the moon is about 1.3 seconds. All the other distances you seek except to the sun, vary greatly depending on the date in question.

If you needed just the times it takes when then planets are in average closest approach, which for some planets only happens once or twice in a lifetime, followup with me. I can help with that. The answers are general and are not specific to a date.

Oh yes, one more distance that won't change much. The distance from the Earth to the center of our galaxy is about 26,000 light years. The light would take 26,000 years to travel the distance, by definition.

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Jesse Martinez

Expertise

General and specific questions about the solar system and stellar and galactic astronomy, are what I can easily answer off the top of my head. For example, what is the largest planet in the solar system? How far away is the moon? Have there been any confirmed planets in orbit around stars other than the sun? How many stars are there? The tougher ones like explaining the big bang theory and black holes I will leave to the PhD’s. Even though I could muster an answer, I would have to research it more than I would like. I would also like to answer questions that involve Astronomy with other sciences, chemistry, biology, physics, geology and mathematics as long as they are not PhD level.

Experience

I have been into astronomy since I was 8 years old. I have kept detailed journals of my observations through small telescopes. Over the years I have participated in amateur observation projects for organizations like ALPO. My personal research has involved "discovering" the moons of Jupiter with a 4½-inch Newtonian reflector without any outside information like charts and tables. In a summer long project, I determined the existence of and plotted the orbits of the four major moons of Jupiter. From these observations, my data on orbital elements was surprisingly accurate (orbital radius and orbital period).

Education/Credentials
80 hours of college credits while studying physics and geophysics. Completed correspondence photography course while in high school. Took two semesters of electronics training at a community college. Studied computers and graduated from a technical school at the turn of the millennium, gaining A+ and Microsoft Certified Professional credentials. Hablo Español. Si quieres preguntar en Español, estoy a su servicio.

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