What is the closest galaxy to milky way ?

These factors threaten north americas ecosystems

What would be the distance of all the planets to the sun in astronomical units?

Why is the huronian supergroup rock formation particularly interesting to scientists? because it looks like a cross-section of a giant, stone encyclopedia because it formed during the period when oxygen began to accumulate in the atmosphere because it contains unusually large amounts of oxygen and sulfur because it dramatically altered the planet's development when it first formed