The Habitable Earth

• Seven things that make life on Earth possible: Goldilocks zone, Water, Sun, Solar System, interstellar cloud of gas and dust, Earth's rotation and the moon, ozone layer
• Goldilocks zone - earth orbits here, where it receives enough energy to allow water to exist as a liquid on its surface
• Water - one of the most essential prerequisites for life
• Sun - a stable long lasting star
• Massive stars - it burns hotter and usually don't live long enough for planets to develop life
• Less massive stars - often unstable and are prone to blasting their planets with bursts of radiation
• Solar system - this comfortably nestled in a safe harbor between major spiral arms, and its nearly circular orbit helps it avoid the galaxy's perilous inner regions.
• Supernovae - collapsing stars
• The interstellar cloud of gas and dust - it gave rise to Earth containing enough radioactive elements to power a churning core for billions of years
• The interstellar cloud of gas and dust - this creates a magnetic field that protects the planet from dangers like solar flares.
• Earth is tilted relative to the sun and wobbles as it spins
• The tiny wobble of the Earth can shift the climate from hot ot very icy every 41,000 years and might vary more without the moon's stabilizing pull.
• Ozone layer blocks harmful rays from the sun, protecting us from skin cancer
• Ancient plant like organisms in the oceans added oxygen to the atmosphere and created a high-altitude layer of ozone that shielded every land species from lethal radiation.