Download Constellations and the Galactic Plane

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Partners _____________________________
Familiar Constellations and the Galactic Plane
Constellations are simply patterns of the brightest stars in the heavens that inspired the
ancients to attribute names and stories to. Orion the hunter, Cygnus the swan, Leo the lion
are all familiar names to northern hemisphere night sky watchers. There are 88 named
constellations, each having numerous stars. This exercise takes you through some of the
most recognizable ones in the October-November sky in the Bay Area.
The patterns of stars remain the same over the ages. That is because the stars, though
moving, are so far away they seem not to move at all compared to the background of other
stars (parallax is so small). So, it should be emphasized that although constellations are
recognized and drawn as two-dimensional pictures connecting stars, the stars are all at
different distances, and just seem to be on a black background fixed at some great distance.
Among the most recognizable constellations are those belonging to stars of the “summer
triangle”, the Big Dipper (Ursa Major) and Little Dipper (Ursa Minor). For observation, do 1, 2
1. Note today’s date and time _________________________________________
2. Find the Big Dipper (look north). Use the pointer stars and locate Polaris. Draw the Big
Dipper (the 7 brightest stars) and the Little Dipper (7 stars, or as many as you can) on Fig.1
below. Label Polaris “P” and pointer stars on the Big Dipper as “A” and “B”. Draw to scale.
Fig.1
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3. Name and label the 7 brightest stars (and their α,β,γ , etc.) in the Big Dipper on Fig.1.
Note: good links are here for constellations and (for example) stars
4. Fill out the table below for the 7 brightest stars in Ursa Major
Table I - Ursa Major
Name
Bayer
(α,β,γ ,
etc.)
Apparent
magnitude
Mass
(M )
Distance
(ly)
Radius
(R )
Type (e.g.,
red giant)
5. Name and label the 6 brightest stars (and their α,β,γ , etc.) in the Little Dipper on Fig.1.
6. Fill out the table below for the 6 brightest stars in Ursa Minor
Name
Table II - Ursa Minor
Bayer
Mass
Apparent
Distance
(α,β,γ ,
(
M )
magnitude
(ly)
etc.)
Radius
(R )
Type (e.g.,
red giant)
7. Now locate the summer triangle – Vega, Altair, and Deneb. Draw and label the 3 stars in
Fig.2 below. Leave room for their constellations Lyra, Aquila, Cygnus, respectively. Cygnus
“the swan” is also known as the “Northern Cross”.
8. Draw the brightest stars (up to 7) in each of their 3 respective constellations.
9. Name and label the 3 brightest stars (if possible) in each constellation on Fig.2.
10. Fill out the table below for the brightest star in Lyra
Name
Table III - Lyra
Bayer
Apparent
Distance
(α,β,γ ,
magnitude
(ly)
etc.)
2
Mass
(M )
Radius
(R )
Type (e.g.,
red giant)
Fig.2
11. Fill out the table below for the 4 brightest stars in Cygnus
Name
Table IV - Cygnus
Bayer
Apparent
Distance
(α,β,γ ,
magnitude
(ly)
etc.)
Mass
(M )
Radius
(R )
Type (e.g.,
red giant)
Radius
(R )
Type (e.g.,
red giant)
Deneb
12. Fill out the table below for the 3 brightest stars in Aquila
Name
Table V - Aquila
Bayer
Apparent
Distance
(α,β,γ ,
magnitude
(ly)
etc.)
Altair
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Mass
(M )
The Galactic Plane
The “milky way” is a faint star-light background across the sky, now hardly visible to us near
cities, that forms the plane of our galaxy. Altair and Deneb are very close to this plane. In fact
the plane is best seen during the summer-fall months.
In November, the milky way is spanned, from southwest to northeast through the zenith, by the
constellations Aquila (with Altair), Cygnus (the “northern cross” with Deneb), Cassiopeia (looks
like a “W”), Auriga (with Capella). The center of the galaxy is in the direction of Sagittarius –
on the southwest horizon below Aquila.
13. In Fig.2, Draw a dashed line through Altair and Deneb. This line lies roughly along the
galactic plane.
14. In Fig.3 below Deneb is drawn on the left. Locate and draw Cassiopeia near the middle of
the figure (“W” should be inverted).
15. If visible, locate and draw and the constellation Auriga around its alpha star Capella (near the
northeast horizon) on the right in Fig.3.
Deneb
Capella
Fig.3
Note that the plane of our Milky Way galaxy runs roughly through Altair (Aquila), Deneb
(Cygnus), Cassiopeia, and Capella (Auriga).
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16. Fill out the table below for the 4 brightest stars in Cassiopeia.
Name
Table VI - Cassiopeia
Bayer
Mass
Apparent
Distance
(α,β,γ ,
(
M )
magnitude
(ly)
etc.)
Radius
(R )
Type (e.g.,
red giant)
17. Fill out the table below for the 4 brightest stars in Auriga. One of the stars “Elnath” is
actually also a part of Taurus “the bull” (Beta Tau) to the east and “above” the galactic plane.
Name
Table VII - Auriga
Bayer
Mass
Apparent
Distance
(α,β,γ ,
(
M )
magnitude
(ly)
etc.)
Radius
(R )
Type (e.g.,
red giant)
18. Note that the “anti-center” of the galaxy is located here – the direction opposite to the
galactic center. The anti-center points directly out of the galaxy (the center is toward
Sagittarius). Place an “X” on Fig.3 at the anti-center. When you’ve viewed the “anti-center”
link check here ______________
19. Locate the plane of the ecliptic in the sky (use Jupiter and where the sun is now). Locate the
plane of the galaxy in the sky. Estimate the angle between the plane of the ecliptic and the plane
of the galaxy. Angle is about __________________________
20. “The Kids” fall right on the galactic plane. Fill out the table below for the three “Kids”.
Name
Table VIII – The Kids
Bayer
Mass
Apparent
Distance
(α,β,γ ,
(M )
magnitude
(ly)
etc.)
Radius
(R )
Type (e.g.,
red giant)
21. Familiarize yourself with our neighborhood within 10 light years with this link. Note that
one of the brightest stars in the night sky - Sirius – and its constellation Canis Major (“big dog”)
is not visible until winter. After you’ve viewed the link check here _______________
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22. Zoom out to our neighborhood within 250 light years. Note how “close” Capella and Vega
are. Aldebaran is the red giant “eye” in Taurus the bull, not far from Capella in the night sky.
Zoom out again to 5000 light years to see our position in the “Orion Arm” of our Milky Way
galaxy, then zoom out to see where we are within 50,000 light years. After you’ve viewed the
links check here _______________
23. Finally, to get a view of the constellations from a galactic perspective, look at this galactic
atlas. You may prefer this alternative view. As stated, there are about “9000 stars are visible to
the naked eye”. On the left of the galactic center (Scorpius and Sagittarius) are Aquila (Altair),
Cygnus (Deneb), Cassiopeia and Auriga (Capella). These are easily viewable in the summer and
fall. The right hand side of the galaxy ( Canis Major, Orion, Crux) are more easily viewed in the
winter and spring. Notice the Zodiac (running along the ecliptic) includes Gemini, Cancer, Leo,
Virgo, all constellations well off the galactic plane. After you’ve viewed the links check here
_______________
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