Galaxy Horizon – 4/20 at Midnight

On April 20th (4/20) at midnight Earth’s horizon (in northern latitudes) lines up perfectly with the plane of the entire Milky Way galaxy. The galaxy “wraps around” our view of the sky and we can see into and through the plane of the galaxy.

Starinastar.com galaxy horizon visualization. Shows the galaxy plane lined up with the local horizon at midnight on April 20th. This happens every year.
The Milky Way galaxy lines up perfectly with your local horizon view on April 20th (4/20) at midnight each year.

At this moment when you look out around you at the horizon, you are looking into the plane of the Milky Way galaxy.

How to See the Milky Way Galaxy Plane

Look southward (and a little bit east) and you are looking toward the center of the galaxy. Look northward (and a little bit west) and you are looking toward the outer edges of the galaxy.

Why does the galaxy line up with the horizon?

Each year on 4/20 the galaxy lines up with the horizon – an “event” I call the Galaxy Horizon. In fact, this “event” occurs every day! It’s just an interesting coincidence that the alignment happens on 4/20 at midnight. Each day the galaxy lines up again with the horizon but it happens 4 minutes earlier.

Blue Moon, Dark Moon, Nose Moon, Tail Moon

What is a Blue Moon?

The year 2018 is a Blue Moon bonanza! There was one in January and one on March 31st. The next one won’t arrive until October 2020. But, don’t worry… we’ve got 3 other types of moons lined up for you.

A blue moon tinted blue to make it look like the moon is actually blue. A blue moon means 2 full moons in a calendar month.
A Blue Moon. (This image was tinted to make it blue. No, a Blue Moon is not blue.)

The Basics

A Blue Moon happens when there is a Full Moon on the 1st* day of the month and a Full Moon on the last* day of the month. Two full moons in one month!

In other words, a Blue Moon is when there is a full moon twice in the same month. These two full moons always happen on the 1st or 2nd and the 30th and 31st of a month. “Blue Moon” is just a name for the second moon in that month – the moon does not turn the color blue.

Read on to learn about how the Blue Moon came to be and some suggestions for giving the other moon phases “Blue Moon” style names when they appear twice in a month. Suggestions are: Dark Moon, Nose Moon, and Tail Moon.Click here to continue reading…

Stars in Your Eyes

Graphic showing text and milky way galaxy of stars. Stars end their trips in your eyes

The light of a star…

…no matter how long it has been traveling through space, ends its journey in your eye. The light hits your retina and is transformed into thought. As long as you let that star light stream into your view, the star itself lands in you and settles its motion.

When I was 17 years old I went on a weekend retreat run by the Christian Brothers near Melbourne, Australia. It was a weekend of spiritual teaching, introspection and reflection.

Saturday night, one of the other boys at the retreat surprised me. As we stood outside under the stars, he spoke in that matter-of-fact way typical of Australians.

Click here to continue reading…

Groundhog Day Shadow Tracker

Physical Astronomy Tool by Daniel Cummings

Groundhog Day Shadow Tracker Lesson Plan
It’s Groundhog Day!

What better way to celebrate Groundhog Day than to Build your own Groundhog Day Shadow Tracker


Sun Tracker Window Gel Cling and Stickers to track the Sun

UPDATE: We now sell an astronomy gift called the Sun Tracker that teaches you the same Basic Astronomy Lesson that the Ground Hog does! You can learn all about the apparent movements of the Sun and the analemma.

It’s called the Sun Tracker and you can purchase one right from this website.


Let’s do some Physical Astronomy. The experience will help you to understand the movement of the earth and sun through the seasons. You will build a scientific instrument that is also a fun garden decoration and you will be able to track the Groundhog’s Shadow all Spring!

Click here to continue reading…

A new star will appear in the sky in 2022

Binary star merge to form a new star - a star in a starAn amazing thing is about to happen! A Star in a Star will be born.

EDIT (Nov. 19, 2021): It turns out that the underlying observation data had a timing flaw that makes it “unlikely” that the new star will be born in 2022. See this Wikipedia page about the new Star for more information.

You  can witness the birth of a new star in the night sky.  The new Star already has a birthday: 2022!

According to scientists, the new star will form when two stars that are orbiting each other grow so close that they merge into one.

The new star will appear in the constellation Cygnus. You can see the approximate location marked by a red circle in the Stellarium screenshot here:

A screenshot of Stellarium showing the new star location under the constellation Cygnus's left wing

The image of the two blue stars on the home page of this Star in a Star site shows what scientists think it looks like now. This impressive video shows an artist’s rendering of the star merge.

In the pair, one star is larger than the other so in the end, there will be a new star…  A Star in a Star.

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