Blue Moon: All you need to know

Isn’t a Blue Moon the 2nd full moon of a calendar month? Why isn’t that the case this month? How did Blue Moons become part of folklore, anyway? The story of Blue Moons, here.

A light blue-colored moon, created via photo processing.

Only 2 full moons in a season possible?

We know it’s possible to squeeze 4 full moons into a single season. But can a season have just 2 full moons? Turns out it can.

Arcturus cuts through the galaxy’s disk

Arcturus isn’t moving solely within the flat disk of our Milky Way galaxy. It’s cutting perpendicularly through the disk. Millions of years from now, it’ll be lost from view, at least for those who are earthbound and looking with the eye alone.

Photo of blue-white star Spica.

Spica is a whirling double star

Spica’s 2 stars orbit a common center of gravity in only 4 days. Their mutual gravity distorts each star into an egg shape, with the pointed ends facing each other.

Find the radiant point for the Eta Aquariid meteor shower

Eta Aquariid meteors radiate from the Y-shaped group of stars called the Water Jar in the constellation Aquarius. Here are 2 ways to find it.

Comet Halley’s 2 meteor showers

The famous Comet Halley spawns the Eta Aquariids – going on now – and the Orionids in October. Plus where the comet is now, parent bodies of other meteor showers … and Isaac Newton’s Vis-viva equation, his poetic rendition of instantaneous motion.

When does Ramadan begin in 2019?

Earliest sightings of a young crescent in the west after sunset mark the start of the Islamic holy month of Ramadan. When will the UAE’s moon-sighting committee see this month’s young moon? If they’re using binoculars and telescopes (and have clear skies), they might see it May 5. For the eye alone, the date is probably May 6.

Why do we celebrate May Day?

Happy May Day! A few words about this annual celebration, which has its roots in astronomy.

May guide to the bright planets

Mars pops out at nightfall. Jupiter comes up later, and Saturn later still. Venus sits low in the east at dawn. Southern Hemisphere skywatchers might catch Mercury in early May, but it’s lost in the sunrise from middle and far northern latitudes.

Alpha and Beta Centauri, pointing to Crux.

Northerners’ guide to Southern Cross

The Southern Cross climbs highest – due south – in the evening around now. Latitudes like Hawaii can see it. It’s possible to see from latitudes like the far-southern contiguous U.S., but difficult.

All you need to know: Eta Aquariid meteors

The new moon on May 4 will provide inky black skies for this year’s Eta Aquariid meteor shower. No matter where you are on the globe, watch for meteors on the several mornings around May 5.

Chart showing location of Lyrid meteor shower radiant point.

Find the Lyrid meteors’ radiant point

You don’t need to find the radiant to see the meteors. But it’s fun to spot, near the bright star Vega.

Why does the moon seem to follow me?

Here’s something you – or your kids – might have noticed: When you’re in a moving car, earthly objects get left behind, but the moon seems to follow. Why?

Lyrid meteor shower: All you need to know

In 2019, April 23 is the expected peak morning. There will be a bright waning gibbous moon in the sky. Want to make the most of this year’s Lyrid meteor shower? Here’s how.

Observatory dome in foreground, Milky Way in background, and Alpha Centauri's position marked.

Alpha Centauri, star system closest to our sun

We see this nearly star system as a single star in our sky, but it’s really 3 stars. Of the 3, Proxima is closer to our sun than any other known star.

Alpha and Beta Centauri, pointing to Crux.

Beta Centauri is a Southern Pointer Star

Beta Centauri – aka Hadar – joins Alpha Centauri in pointing to the Southern Cross. Like Alpha, Beta Centauri is also 3 stars, but 2 of Beta’s stars will someday become nearby supernovae.

Clock time and sun time agree in mid-April

Sundial and clock agree every year in middle April. It means that, when the midday sun climbs highest, the sundial reads 12 noon and your local clock says 12 noon.

Sunset on Mars.

Does Mars have a North Star?

Will future Mars explorers have a North Star to guide them?

Leo? Here’s your constellation

Leo the Lion is one of the easiest constellations to identify in the night sky. April and May are great months to spot it.

Watch the sun’s shift on your horizon

Looking for an easy, but profound, sky activity? Note how far the sunset moves on your horizon, as spring shifts toward summer, or autumn toward winter, on your part of the globe.