To recreate a projection of the transit of Venus

[phack]

Hi! Newly registered here, with an optics question.

I was going through some photos I took of the transit of Venus this year, where I'd used a reflecting telescope to project the image of the sun and the passing planet onto a piece of white paper. Image: http://imgur.com/3mdUN

I showed it to some friends and one responded words to the effect, "I know I should be amazed, but I can't help thinking I could recreate that with a flashlight and a sharpie." I understand the sun is much brighter than any flashlight: my question really relates to the focus of the image produced.

My counter to this point was that for the sun/Venus system, one could reach an arbitrary level of resolution, whereas with a flashlight, the light source and sharpie blackout would be so close that the "planet" could never achieve the same level of focus..? I admit, I don't really know what I'm talking about, so I'd really appreciate anyone's advice/expertise.

Thanks in advance.

 

[eljose79]

Hi there! Welcome to the forum and thanks for sharing your experience with the transit of Venus. It's always exciting to witness rare astronomical events like that.

To address your friend's point, you are correct in saying that the sun is significantly brighter than any flashlight, which is why it is not recommended to look at the sun directly. However, the focus of the image is also an important factor in creating a clear and detailed image.

In your case, the reflecting telescope is specifically designed to focus light and produce a clear image, whereas a flashlight and sharpie would not have the same level of precision in focusing the light. This is because of the optics and mechanics involved in the design of a telescope.

Additionally, the size and distance of the sun and Venus also play a role in the resolution of the image. The sun is much larger and farther away than any object you could create with a flashlight and sharpie, which allows for a higher level of detail and resolution in the image.

I hope this helps clarify the differences between using a reflecting telescope and a flashlight and sharpie. Keep exploring and learning about optics and astronomy, and feel free to ask any other questions you may have. Happy stargazing!