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# callum-herries's solution

## to Space Age in the Clojure Track

Published at Mar 15 2021 · 0 comments
Instructions
Test suite
Solution

Given an age in seconds, calculate how old someone would be on:

• Earth: orbital period 365.25 Earth days, or 31557600 seconds
• Mercury: orbital period 0.2408467 Earth years
• Venus: orbital period 0.61519726 Earth years
• Mars: orbital period 1.8808158 Earth years
• Jupiter: orbital period 11.862615 Earth years
• Saturn: orbital period 29.447498 Earth years
• Uranus: orbital period 84.016846 Earth years
• Neptune: orbital period 164.79132 Earth years

So if you were told someone were 1,000,000,000 seconds old, you should be able to say that they're 31.69 Earth-years old.

If you're wondering why Pluto didn't make the cut, go watch this youtube video.

## Source

Partially inspired by Chapter 1 in Chris Pine's online Learn to Program tutorial. http://pine.fm/LearnToProgram/?Chapter=01

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### space_age_test.clj

``````(ns space-age-test
(:require [clojure.test :refer [deftest is]]
space-age))

(defn- rounds-to
[expected actual]
(is (= (Math/round (* 100.0 expected))
(Math/round (* 100.0 actual)))))

(deftest age-in-earth-years
(rounds-to 31.69 (space-age/on-earth 1000000000)))

(deftest age-in-mercury-years
(let [seconds 2134835688]
(rounds-to 67.65 (space-age/on-earth seconds))
(rounds-to 280.88 (space-age/on-mercury seconds))))

(deftest age-in-venus-years
(let [seconds 189839836]
(rounds-to 6.02 (space-age/on-earth seconds))
(rounds-to 9.78 (space-age/on-venus seconds))))

(deftest age-on-mars
(let [seconds 2329871239]
(rounds-to 73.83 (space-age/on-earth seconds))
(rounds-to 39.25 (space-age/on-mars seconds))))

(deftest age-on-jupiter
(let [seconds 901876382]
(rounds-to 28.58 (space-age/on-earth seconds))
(rounds-to 2.41 (space-age/on-jupiter seconds))))

(deftest age-on-saturn
(let [seconds 3000000000]
(rounds-to 95.06 (space-age/on-earth seconds))
(rounds-to 3.23 (space-age/on-saturn seconds))))

(deftest age-on-uranus
(let [seconds 3210123456]
(rounds-to 101.72 (space-age/on-earth seconds))
(rounds-to 1.21 (space-age/on-uranus seconds))))

(deftest age-on-neptune
(let [seconds 8210123456]
(rounds-to 260.16 (space-age/on-earth seconds))
(rounds-to 1.58 (space-age/on-neptune seconds))))``````
``````(ns space-age)

(defn on-planet
[orbital-period-earth-years]
(fn [seconds]
(/ seconds (* orbital-period-earth-years 31557600.0))))

(def on-earth (on-planet 1.0))
(def on-mercury (on-planet 0.2408467))
(def on-venus (on-planet 0.61519726))
(def on-mars (on-planet 1.8808158))
(def on-jupiter (on-planet 11.862615))
(def on-saturn (on-planet 29.447498))
(def on-uranus (on-planet 84.016846))
(def on-neptune (on-planet 164.79132))``````