Constellations in SDSS data 1 star

People have looked at the sky for thousands of years. When ancient people looked up, they saw the same thing you see today: beautiful stars. They saw patterns in the stars. Today, we call these patterns “constellations.”
You may have heard of some famous constellations, like Orion the Hunter. Astronomers today recognize 88 constellations, and we use them to divide the sky into 88 regions, as a cosmic address of sorts. This makes objects in the sky easier to find. Sometimes when astronomers talk about something in the sky, they often name it after the constellation it is closest to. For example, the large spiral galaxy M31 is near the constellation Andromeda, and so astronomers call it the Andromeda Galaxy.

In this page and linked set of activities you will:

  • learn about constellations
  • discover your own constellations in SDSS imaging or SDSS plates
  • learn about how the SDSS telescope views some of the official 88 constellations in the nights sky.

Part 1 – what are constellations?

Let’s start with a simple example: a made-up constellation. Your teacher will divide you into groups, and they will give you a worksheet with a made-up collection of stars. Study it, then look at the pictures below. Pretend you are looking at stars in the sky. What do you see?

Someone from your group should describe what you see to the rest of the class. What did the other group see? Can you see what they saw? Some will have seen a dove, others a horse, and others something else entirely.

A drawing of a dove next to a drawing of a horse

This activity shows what ancient people did when they saw the stars. You can think of yourself as a member of an ancient culture. When you looked at the sky and saw those stars, you saw a dove or a horse. Whenever you looked at those stars, that’s what you saw. The other group was like another ancient culture. They saw the other shape (horse or dove) – then every time they looked at those stars, they saw that shape.

Of course, there aren’t really doves or horses in the sky – just stars.The ancient people saw the patterns in the stars that they had always seen, just likeyou saw the pattern you had seen from your handout. Now that you understand what constellations are, let’s look at a real constellation.

Part 2 – the stars of Orion

Let’s have a closer look at the constellation of Orion:

Orion

The Constellation Orion. Copyright Bernd Mienert. Courtesy of the Astronomical Image Data Archive.

 

When the ancient Greeks saw Orion, the shape reminded them of a hunter. The bright stars in the four corners were his shoulders and feet. The three horizontal stars in the middle were his belt. The three vertical stars below were his sword. The Greeks told a story about Orion. He was a brave but proud hunter who was killed by a scorpion. When he died, the gods put him in the sky to remember him.

 

Study the picture of Orion above. Orion consists of seven major stars: two for his shoulders, two for his feet,and three for his belt. Copy the position of the stars to a piece of paper, and number the stars from 1 to 7, with the number 1 being the star that you think is closest to Earth.

Each star in Orion has a name, and astronomers have measured how bright and how far away each star is. Astronomers measure how bright a star is with a number called magnitude. The brighter the star, the lower the magnitude, and a difference of 5 in magnitude means a factor of 100 difference in brightness.

Starstars

 The stars to the left are magnitude 13 and 18, so they differ by a factor of 100. Similarly, a magnitude 1 star is 100 times brighter than a magnitude 6 star.

Astronomers measure distance in light-years. One light-year is the distance light travels in one year: 9,458,000,000,000 kilometers. A light-year is a long way: to go one light-year in the Space Shuttle would take about 40,000 years!

The table below shows magnitudes and distances for the seven stars that make up Orion.

Now number the stars in your drawing according to how far away they are, using the distances in the table below. Do they have the same numbers as you had guessed before? If not, can you think of why not?

Star Name

Part of Orion

Magnitude

Distance (light-years)

Betelgeuse

Left shoulder

0.45

427

Saiph

Left foot

2.07

720

Bellatrix

Right shoulder

1.64

243

Rigel

Right foot

0.18

773

Alnitak

Left belt

1.82

815

Alnilam

Center belt

1.69

1,350

Mintaka

Right belt

2.41

916

 

Part 3 – Discovering your own SDSS constellations

You are now ready to discover and invent new constellations in SDSS data. You can work on either images or spectra. SDSS has taken so many images and spectra of objects in the sky, that many of them have never been looked at by a human – I wonder what you will find?

To discover new constellations using SDSS images of the sky, start here:
Discovering constellations in SDSS imaging

To discover new constellations using SDSS plates, start here: (N.B.: this activity requires a physical SDSS plug plate)
Discovering constellations in SDSS plates

To discover which of the official 88 constellations are in SDSS data, starting from your own photograph of the sky, start here:
Matching sky constellations with SDSS imaging