diff --git a/Rakefile b/Rakefile
new file mode 100644
index 00000000..f29f7c93
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,9 @@
+require 'rake/testtask'
+
+Rake::TestTask.new do |t|
+  t.libs = ["lib"]
+  t.warning = true
+  t.test_files = FileList['specs/*_spec.rb']
+end
+
+task default: :test
\ No newline at end of file
diff --git a/lib/main.rb b/lib/main.rb
new file mode 100644
index 00000000..669cfe5a
--- /dev/null
+++ b/lib/main.rb
@@ -0,0 +1,105 @@
+require_relative 'planet.rb'
+require_relative 'solar_system.rb'
+
+def build_solar_system
+  solar_system = SolarSystem.new("Sun")
+  earth = Planet.new('Earth', 'blue-green', 5.972e24, 1.496e8, 'Only planet known to support life')
+  mars = Planet.new('Mars', 'red', 6.4171e23, 2.29e8, 'Mars has two moons called Phobos and Deimos')
+  mercury = Planet.new('Mercury', 'white', 3.3022e23, 6.98169e7, 'Mercury is the smallest planet in the solar system')
+  jupiter = Planet.new('Jupiter', 'orange', 1.8982e27, 7.79e8, 'Jupiter is the largest planet in the solar system')
+  venus = Planet.new('Venus', 'yellow', 4.8675e24, 1.082e8, 'Venus has the longest rotation period of any planet in the Solar System')
+  uranus = Planet.new('Uranus', 'baby blue', 8.6810e25, 2.75e9, 'Uranus is named after the Greek mythological figure Ouranos, the God of the sky')
+  solar_system.add_planet(earth)
+  solar_system.add_planet(mars)
+  solar_system.add_planet(mercury)
+  solar_system.add_planet(jupiter)
+  solar_system.add_planet(venus)
+  solar_system.add_planet(uranus)
+  return solar_system
+end
+
+def ask_planet_details(solar_system)
+  puts "Which planet do you want to learn about?"
+  puts "#{solar_system.list_planets}"
+  input_planet = gets.chomp
+  begin
+    puts "#{solar_system.find_planet_by_name(input_planet).summary}"
+  rescue ArgumentError => e
+    puts e
+  end
+end
+
+def add_new_planet(solar_system)
+  puts "What is the name of the planet you want to add?"
+  planet_name = gets.chomp
+  
+  puts "What is the color of your new planet?"
+  planet_color = gets.chomp
+
+  puts "What is the mass of your new planet?"
+  planet_mass = gets.chomp.to_i
+
+  puts "How far is your new planet from the Sun?"
+  planet_distance = gets.chomp.to_i
+
+  puts "Please add some fun facts about your new planet"
+  planet_fact = gets.chomp
+
+  begin
+    new_planet = Planet.new(planet_name, planet_color, planet_mass, planet_distance, planet_fact)
+    solar_system.add_planet(new_planet)
+    puts "Congratulations! You added #{planet_name}"
+  rescue ArgumentError => e
+    puts e
+  end
+end
+
+def find_distance_between(solar_system)
+  puts "What is the name of the first planet?"
+  first_planet = gets.chomp
+  puts "What is the name of the second planet?"
+  second_planet = gets.chomp
+  begin
+    puts "The distance between #{first_planet} and #{second_planet} is #{solar_system.distance_between(first_planet, second_planet)} km"
+  rescue ArgumentError => e
+    puts e
+  end
+end
+
+def main
+  sun = build_solar_system
+
+  options = {
+    1 => "List planets", 
+    2 => "Planet details", 
+    3 => "Add a planet", 
+    4 => "Find distance between two planets", 
+    5 => "Exit"
+  }
+  questions = "\nWhat do you want to do next?\n"
+  options.each { |key, value|
+    questions += "#{key}. #{value}\n"
+  }
+  
+  while true
+    puts questions
+    input = gets.chomp.downcase
+    case input
+    when "exit", "5"
+      puts "Goodbye"
+      return
+    when "list planets", "1"
+      puts "#{sun.list_planets}"
+    when "planet details", "2"
+      ask_planet_details(sun)
+    when "add a planet", "3"
+      add_new_planet(sun)
+    when "find distance between two planets", "4"
+      find_distance_between(sun)
+    else
+      puts "You chose an invalid option. Please choose again"
+    end
+  end
+end
+
+main
\ No newline at end of file
diff --git a/lib/planet.rb b/lib/planet.rb
new file mode 100644
index 00000000..e2dd94cc
--- /dev/null
+++ b/lib/planet.rb
@@ -0,0 +1,23 @@
+class Planet
+  attr_reader :name, :color, :mass_kg, :distance_from_sun_km, :fun_fact
+
+  def initialize(name, color, mass_kg, distance_from_sun_km, fun_fact)
+    if !mass_kg.is_a?(Numeric) || mass_kg <= 0
+      raise ArgumentError.new("Planet mass has to be a positive number")
+    end
+
+    if !distance_from_sun_km.is_a?(Numeric) || distance_from_sun_km <= 0
+      raise ArgumentError.new("Distance from the sun has to be a postive number.")
+    end
+
+    @name = name
+    @color = color
+    @mass_kg = mass_kg
+    @distance_from_sun_km = distance_from_sun_km
+    @fun_fact = fun_fact
+  end
+
+  def summary
+    return "The #{name} is #{color}, weighs #{mass_kg} kg, and is about #{distance_from_sun_km} km from the sun. Fun fact: #{fun_fact}"
+  end
+end
\ No newline at end of file
diff --git a/lib/solar_system.rb b/lib/solar_system.rb
new file mode 100644
index 00000000..61a4d5da
--- /dev/null
+++ b/lib/solar_system.rb
@@ -0,0 +1,44 @@
+require_relative 'planet.rb'
+
+class SolarSystem
+  attr_reader :star_name, :planets
+
+  def initialize(star_name)
+    @star_name = star_name
+    @planets = Array.new
+  end
+
+  def add_planet(planet)
+    @planets.each do |p|
+      if p.name.casecmp(planet.name) == 0
+        raise ArgumentError.new("Planet already exists")
+      end
+    end
+
+    @planets << planet
+  end
+
+  def list_planets
+    list = "Planets orbitting #{star_name}:\n"
+    @planets.each_index { |i|
+      list += "#{i + 1}. #{@planets[i].name}\n"
+    }
+    return list
+  end
+
+  def find_planet_by_name(name)
+    @planets.each do |planet|
+      if planet.name.casecmp(name) == 0
+        return planet
+      end
+    end
+
+    raise ArgumentError.new("There is no such planet #{name}")
+  end
+
+  def distance_between(planet1, planet2)
+    distance = find_planet_by_name(planet1).distance_from_sun_km - find_planet_by_name(planet2).distance_from_sun_km
+    return distance.abs
+  end
+end
+
diff --git a/specs/planet_spec.rb b/specs/planet_spec.rb
new file mode 100644
index 00000000..d9bb1363
--- /dev/null
+++ b/specs/planet_spec.rb
@@ -0,0 +1,54 @@
+require "minitest/autorun"
+require "minitest/reporters"
+require "minitest/skip_dsl"
+
+require_relative "../lib/planet.rb"
+require_relative "../lib/solar_system.rb"
+
+Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
+
+describe "Planet class" do
+  it "outputs a string when you invoke its summary method" do
+    mars = Planet.new('Mars', 'red', 6.4171e23, 2.29e8, 'Mars has two moons called Phobos and Deimos')
+
+    expect(mars.summary).must_be_instance_of String
+  end
+
+  it "raises argument error if you input a negative number for the planet's mass" do
+    expect {
+      Planet.new('Mars', 'red', -1, 2.29e8, 'Mars has two moons called Phobos and Deimos')
+      }.must_raise ArgumentError
+  end
+
+  it "raises argument error if you input 0 for the planet's mass" do
+    expect {
+      Planet.new('Mars', 'red', 0, 2.29e8, 'Mars has two moons called Phobos and Deimos')
+      }.must_raise ArgumentError
+  end
+
+  it "raises argument error if you input a negative number for the planet's distance from the Sun" do
+    expect {
+      Planet.new('Mars', 'red', 6.4171e23, -2, 'Mars has two moons called Phobos and Deimos')
+      }.must_raise ArgumentError
+  end
+
+  it "raises argument error if you input 0 for the planet's distance from the Sun" do
+    expect {
+      Planet.new('Mars', 'red', 6.4171e23, 0, 'Mars has two moons called Phobos and Deimos')
+      }.must_raise ArgumentError
+  end
+end
+
+describe "solar_system class" do
+  it "returns a list of type String of planets orbitting the star" do
+      
+    earth = Planet.new('Earth', 'blue-green', 5.972e24, 1.496e8, 'Only planet known to support life')
+    mars = Planet.new('Mars', 'red', 6.4171e23, 2.29e8, 'Mars has two moons called Phobos and Deimos')
+    sun = SolarSystem.new("Sun")
+    sun.add_planet(earth)
+    sun.add_planet(mars)
+
+    expect(sun.list_planets).must_be_instance_of String
+  end
+end
+