Dr. Jeff's Blog on the Universe

Weekly Challenge 5: Dr. Jeff’s Interplanetary Travel Agency

Posted by DrJeff on July 13th, 2009

Filed under 1.1. Dr. Jeff's Weekly Challenge, 4. The Earth, 5. Space Science, 5.1. Our Solar System, 5.1.2. The Moon, 5.1.3. Planets, 6. Cool Spacecraft

Apollo--Apollo-module-orb-002

This post is a Dr. Jeff’s Weekly Challenge.

Photo caption: Photograph by Michael Collins in Apollo 11 command module Columbia, as Neil Armstrong and Buzz Aldrin return from the lunar surface in Eagle. With the exception of Michael Collins, the entire human race is in the picture. It happened almost exactly 40 years ago. Eagle blasted off from the surface at 1:54:00 pm EDT, July 21, 1969.

I decided to start a new business. I know space flight for us average folk is just around the corner. As a shrewd business person (hah) I recognize the market potential for interplanetary vacation travel. So I’m therefore happy to report that I’ve just established my new company—Dr. Jeff’s Interplanetary Travel Agency, LLC, and I need some help from you all in designing my marketing material. I’m thinking images of alien vistas is the way to really entice clients.

Last night I happened to look up at the Moon as it was rising above the trees (read why HERE) ,and I thought to myself “Wow! If I didn’t live on Earth, a picture of that would certainly make me want to visit Earth!”

So I started imagining the view from the surface of other worlds. In particular, I’m thinking of a tour package to moons of some of the planets, with stays at the Best Western Satellite Hotels, each located a comfortable distance from the regional spaceport. (Sorry, the Four Seasons and Hilton Hotels only wanted to build on the planets.)

I’m hiring you as my interplanetary photographer. I’d like you to travel to some moons and get me some cool pictures for my brochure. For each shot, I’d like something comparable to what I saw when I looked at the full Moon from Earth.

Here now the Challenge—

From Earth’s surface I have a sense of how big the full Moon looks in my sky. So let’s use the full Moon’s apparent size from Earth as a ‘ruler’.

If you were on the surface of the Moon, how big would Earth appear in your sky compared to the full Moon from the surface of Earth?

And now for the other marketing materials I need—

How big would:

Mars appear from the surface of its moon Phobos?

Jupiter appear from the surface of its moon Io?

Saturn appear from the surface of its moon Tethys?

Uranus appear from the surface of its moon Ariel?

Neptune appear from the surface of its moon Triton?

Pluto appear from the surface of its moon Charon?

And by the way, when you’re on the surface of these other worlds, take a look around and tell me what you see. I want to have a really great description of the local landscape for the travel brochure!

Hint: you need to think about 2 things for each question:

1) what’s the diameter of the planet your looking at compared to the diameter of our Moon?

2) what is the distance between the surface you’re on and the planet you’re looking at compared to the Earth-Moon distance?

Answer now posted here!

Photo credit: Michael Collins (NASA)