Download Planets in the Sky

Key
Phys 102 Astronomy
Name ____________________
POSITIONS
OF THE
PLANETS
PLANETARY POSITIONS WITH RESPECT TO THE SUN:
Use appendix 11 in the Field Guide for September 15, 2016 to complete the following table:
Planets
in order
of orbit
distance
from
the Sun.
Object
Planetary Longitude
Atlas Chart #
Constellation
Elongation
Mercury (☿)
Venus(♀)
Mars (♂)
Jupiter (♃)
Saturn (♄)
173
168
200
262
181
251
27
27
28
41
27
41
Leo
Leo
Virgo
Ophiuchus
Virgo
Ophiuchus
ZERO!
5° W
27° E
89° E
8° E
78° E
Sol ()
PLANETARY POSITIONS IN THE SKY
The digram below shows an observer looking south at sunset. From the planetary longitude of the sun
and planets abovee, show where the planets will be in the observer’s sky (some may be below the horizon).
Discuss how these positions correspond to the times the planets will be visible to this observer (eg. after
sunset, before sunrise or most of the night).
Sun’s PL + 90°
263°
_______
♄
♂
Observer’s
meridian
♀
Come look
for the
planets
with me!
Sun’s PL ± 180
353°
_______
E
observer
looking
south
Sun’s PL - 90°:
83°
_______
Sun setting on
western horizon
♃
W
☿
Sun’s PL
173°
_______
Planets in the Sky Fall 2016 Solution
9/12/2016
PLANETARY POSITIONS IN THE SOLAR SYSTEM
A view of the solar system as seen FROM ABOVE THE NORTH ECLIPTIC POLE with the sun in the
center is shown below. The line from the Earth (
) to the sun () represents the planetary longitude of
the sun. For each of the five visible planets,
1) Center a protractor on the Earth, measure the elongation angle from the sun's longitude.
2) Use a ruler to determine where this crosses the orbit of the planet you're plotting, and mark the
planet's position on its orbit.
Special Note: Can you be certain where Mercury and Venus are in their orbits? How many positions
for each planet are possible? What information will help you figure this out?
173°
Sol’s Planetary Longitude: __________
Eastern Elongation
Western Elongation
Jupiter: 341°- 169° = 172° W
Aapproaching conjunction.
Venus’ elongation on 9/15: 200 - 173 =
27° E. On 10/1 it will be 220 - 189 =
31° E. Since elongation is increasing,
Venus is on the far side of its orbit.
Mars, Jupiter &
Saturn motion
seen from Earth
Venus & Mercury
motion seen
from Earth
Venus:
200°-273° = 27° E
Mercury:
173°-168° = 5° W
Saturn:
251° - 173° = 78° E
Mars:
262°-173° = 89° E.
Just past Eastern
Quadriture
CENTER PROTRACTOR
ON EARTH!
Mercury’s elongation on 9/15: 173
- 168 = 5° W. On 10/1 it will be
189 – 171 = 18° W, Since
elongation is increasing, Mercury
is on the near side of its orbit and
just past inferior conuction.