A blood moon is a nickname for what scientists call a total lunar eclipse and they happen when the Sun, Earth and a full moon match up perfectly. This causes the moon to come into the Earth’s umbral shadow.
NASA went into detail on its website about how the colouring appears, stating: “Colours are one way for our brains to interpret variations in the physical properties of light. These same properties cause each colour of light to behave differently when passing through a substance like air.
“If you’ve ever looked up at a blue sky, or savoured a fiery sunset, you have seen this phenomenon in action.”
People in cities such as Los Angeles and San Francisco will get the best sightings at moonset, so roughly in the small hours of the morning, according to NASA.
To see the moon in Denver, Albuquerque, Salt Lake City, Boise, Idaho, you should expect to be up at about 5am as it's expected to be visible between 5.11 am and 5.25 am.
For those in Las Vegas, San Francisco, Los Angeles, Seattle, or Portland in Oregon, you’ll have to awake an hour earlier at 4am as the blood moon is estimated to be seen between 4.11 am and 4.25 am.