The Winter Skies

An (indoor) stargaze by Dan Roth

Jupiter

Venus

Orion

Rigel

Orion Nebula1500 ly away12 million yrs old

Canis Major

Sirius

Gemini

Pollux

Castor

Taurus and the Pleiades

400 ly away100 million yrs old

Taurus

Aldebran50 ly away4 solar masses40 solar radii

M45—The Pleiades

Alcyone

N

E

Atlas

Merope

Big Dipper

Not to scale

Mizar

Alcor

Mizar itself is in fact a double star, and each of those components are doubles. The 2 stars in Mizar A orbit each other every 20 days at half the distance from the sun to Mercury.

Leo

Not to scale

Star Trails...

Orion, 4 min exposure. The dotted line in the upper right is probably an airplane, and the long trail in the lower left is probably a meteor.

Canis major, 8 min exposure. The bright trail on the left is Sirius

...and some calculations

S = 206265”/Fmm S = 206265/50 S =4125.3”/mm

So, measuring the length of a trail on the picture, one can calculate how far the star moved across the sky

For Sirius (8 min exp): Trail length is 9mm (4125.3”/mm)*(9mm) = 37127.7” or

about 10 degrees

We can check ourselves by doing the same for Orion, whose exposure was 4 minutes—half that of the Sirius picture. We expect the distance to be half.

Trail length is about 5 mm (we're doing well already!)

(4125.3”/mm)*(5mm) = 20626.5” Multiply this by 2 and we get 4125.3” or

about 11 degrees. This is a bit more than what we were

expecting, but it is only a 1% error, which can be attributed to human errors such as inexact measurements, inexact exposure times and out-of-focus images.

Photo Technical Info.

Jupiter and Venus Rite Aid Color Film (ASA 200), Pentax

Spotmatic, f/1.8, 5 sec exp, tripod w/55mm lens

Orion Kodak TX 400, Pentax K1000, f/2, 60 sec exp,

piggypack w/ 75-205mm zoom lens Canis Major

Kodak TX 400, Pentax K1000, f/2, 60 sec exp, piggypack w/ 75-205mm zoom lens

Gemini Kodak TX 400, Pentax K1000, f/2, 20 sec exp,

tripod w/ 50mm lens Taurus/Pleiades

Kodak TX 400, Pentax K1000, f/2, 30 sec exp, tripod w/ 50mm lens

Taurus Kodak TX 400, Pentax K1000, f/3.8, 5 sec exp,

tripod w/ 75-205mm zoom lens The Pleiades

Kodak TX 400, Pentax K1000, 120 sec exp, prime focus

The Big Dipper (handle) Kodak TX 400, Pentax K1000, f/2, 10 sec exp,

tripod w/ 50mm lens The Big Dipper (bowl)

Kodak TX 400, Pentax K1000, f/2, 20 sec exp, tripod w/ 50mm lens

Leo (body) Kodak TX 400, Pentax K1000, f/2, 20 sec exp,

tripod w/ 75-205mm zoom lens Leo (head)

Kodak TX 400, Pentax K1000, f/2, 20 sec exp, tripod w/ 75-205mm zoom lens

Orion Trails Kodak TX 400, Pentax K1000, f/4, 4 min exp,

tripod w/ 50mm lens Sirius Trails

Kodak TX 400, Pentax K1000, f//22, 8 min exp, tripod w/ 50mm lens