Navigating the Night Sky

When I was a small boy, the night sky fascinated me. I dreamt of going to the stars and being an astrogator like in Robert Heinlein's Starman Jones

Piloting a ship through the stars is no easy matter. So I learned the sky like the back of my hand. First, the constellations.

The constellations were born in ancient times when humans saw outlines of mythical beasts, gods, heroes, and other creatures in the night sky. This allowed them to describe to each other where to look.

Then, as the sky became a familiar territory, I was able to name the stars–by their Greek letters and their Latin names. For example, Aldebaran in the constellation Taurus (the Bull) is designated α Tauri.

Vega, Betelgeuse, and Rigel; I came to know as friends.

With today's software for visualizing, mapping the sky, and pointing a telescope, we may have lost the ability to effectively look at the sky and know where anything is.

So, it's an excellent refresher to become familiar with the stars' positions in the celestial hemisphere. As astronomers using remote telescopes, we are disadvantaged compared to backyard observers.

That lucky crew, in addition to the joys of polar alignment, cold nights, and long hours babysitting their scopes, must know where to point them. Some current instruments, software, and phone apps make it a little more automated. But there is nothing like saying look towards Betelgeuse, Rigel, or even Polaris to become intimate with the cosmos.

Planisphere

A planisphere is a star map that rotates around Polaris based on date and time.

Set your date and time by rotating the paper circle and facing south. You are now aligned in a position that correlates to the stars in the sky.

Star Atlas

A star atlas is a fixed map of the heavens. It does not rotate, so you have to view it relative to the actual location of the stars. Get familiar with the constellations and use them as landmarks on your star atlas.

Ephemeris

An ephemeris is a book with tables that give the trajectory and position of naturally occurring astronomical objects and artificial satellites. It is a little harder to use since it is not a visual graphic. The astronomical location calculated from an ephemeris is often given in the spherical polar coordinate system of right ascension and declination.

There is a software version titled The Photographer's Ephemeris–TPE

See how the light will fall on the land, day or night, for any location on earth.

Photo Ephemeris helps you plan outdoor photography in natural light. It's a map-based Sun, Moon, and Milky Way calculator. Plan your shot with perfect precision.

Understand natural light

The Photographer's Ephemeris is especially designed for photographers working with natural light. If you're shooting landscape, wildlife, architecture, real estate, weddings, or natural light portraits, Photo Ephemeris will tell you everything you need to know about sunlight, moonlight, and starlight.

See directional light on a map

See the exact direction of sunrise and sunset on the ideal map for your location. Follow the changing direction of the sun across the day as you adjust the selected time.

Plan for the future

Choose the dates you're interested in. Whether your trip is tomorrow or ten years from now, you can check out light conditions past, present and future.

Minute-by-minute

The timeline includes key celestial events of the day, including rise, set, civil/nautical/astronomical twilight times, golden hour, moon phase events, new moon visibility and more.

~descriptions by https://photoephemeris.com/en

Using these tools, you can now go star hopping.

What is Star Hopping?

Star hopping is findi ng a difficult object by starting with a recognizable star and 'hopping' from it to other stars until we reach t. he desired target.

Navigating the sky is similar to navigation on land. Using a map for reference, locate a landmark or feature on the map to a corresponding feature on land, then note the direction of the next landmark and try to find it.

The best way to learn star hopping is to use familiar constellations, like the Big Dipper or Orion. Then use these stepping stones as your guide.

You will gain confidence with each success using this technique, planning a star hopping route in the day before giving it a go at night.

#### 03FEB2022 Previously published in TelescopeLive

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