Stars and the Solar System

Appearance (Phases) of the Moon during a month

Phases of the Moon

S U N R A Y S

New

Full

First Quarter

Third Quarter

Waxing Crescent

Waxing Gibbous

Waning Crescent

Waning Gibbous

Earth

2911 2009

Notice the position of Mars, Saturn and Venus with respect to the nearby stars

29 12 2009

A month later, planets have drifted to the east among stars which drift from east to west

29 11 2009 29 12 2009

Motion of planets towards east among stars is clearly seen

29 01 2010

A month later, the sky map shows clearly that the planets move among the stars

http://www.scienceu.com/observatory/articles/retro/retro.html

Retrograde Mars apod.nasa.gov/apod/ap031216.html Credit & Copyright: Tunc Tezel

Sun

Earth

Superior Planet

1

23

4

5

6

1

23

64

5

Stars

Notice how the changing position of the earth in its revolution round the sun and that of the planet causes the retrograde motion of the planet

EarthMoon

Mercury

Venus

Sun

Jupiter

Mars

Saturn

FixedStars

Realm of the Gods

Galileo discovered evidence to support Copernicus’ heliocentric theory when he observed four moons in orbit around Jupiter. Beginning on January 7, 1610, he mapped nightly the position of the 4 “Medicean stars” (later renamed the Galilean moons). Over time Galileo deduced that the “stars” were in fact moons in orbit around Jupiter. [Adapted from Galileo Galilei, 1610, Sidereus Nuncius (“The Starry Messenger.”)]

Possibly the most compelling argument Galileo made in favor of the Heliocentric Universe of Copernicus was based on the observations of Venus. Galileo observed the phases of Venus throughout the year. At times Venus presented a small but circular disk and at other times a large crescent. Based on these facts as illustrated in his drawings in Sidereus Nuncius, Galileo reasoned that Venus must orbit the Sun; proof of the Copernican Universe.

Orbits of the Three Inner Galilean Moons An animation of the three-way mean motion resonance that guarantees the stability of the Jovian system. Io orbits Jupiter in 1.77 days (about 43 hours). The next moon, Europa, completes an orbit in twice that period (3.55 days), while the third moon, Ganymede, completes an orbit in twice the period of Europa (7.15 days). In each case the orbital period defines the day/night cycle. All four Galilean moons always turn the same hemisphere to Jupiter because of tidal drag. Wikimedia image created 2006 by Splarka.

www.deepfly.org/TheNeighborhood/GalileanMoons.html

Sun

Venus

Earth

Phases of Venus

47°

V

E

Sun

Venus is always within an angle of 47° of the sun. That is why it is seen either just after sunset (evening ‘star’) or just before sunrise ( morning ‘star’).

http://www.windows.ucar.edu/tour/link=/comets/comet_model_interactive.html

http://www.classzone.com/books/earth_science/terc/content/visualizations/es2706/es2706page01.cfm?chapter_no=27

http://www.st-andrews.ac.uk/~bds2/ltsn/ljm/JAVA/COMETORB/COMET.HTM

Solar System

Not to Scale

Venus

Earth

Saturn

Jupiter

Asteroids

Mars

Mercury

Neptune

SUN

Uranus

Jupiter Mars

EarthVenus

Mercury

Neptune

Uranus

Saturn

Jupiter

Inner Planets

Outer Planets

The Solar SystemUsing just one scale it is difficult to show both the inner and the outer solar system in the same diagram. On the left is the complete solar system. On the right is the blow up of the inner solar system.

NASA

Mercury

Venus

Earth

Moon

Mars

Jupiter

Saturn

Uranus

NeptuneAsteroid (253) Mathilde, about 59 km x 47 km

NASA

Comet West NASA

Piece of a meteorite

NASA

Pole Star

All the stars belonging to a constellation are not at the same distance, as shown here for Ursa Major (Saptarishi)

NASA

Constellation Orion, visible in winter

Constellation Leo, a zodiacal constellation

Source : ganymede.nmsu.edu/tharriso/ast110/class05.html

Ecliptic

Zodiac Belt

There are 12 constellations (Rashis) in the Zodiac. The sun stays in each constellation for about a month. On 21 August the sun appears to be in Leo. On 21 July it is in Cancer. On 21 March it is in Pisces.

1 May 2010 19:00 pm

1 May 2010 22 pm

2 May 2010 01 am

2 May 2010 04 am

1 May 2010 19 pm

1 May 2010 22 pm

2 May 2010 01 am

2 May 2010 04 am

Great Bear at six-hour interval during a night.

Star Trails in Northern SkiesCredit and Copyright: David Malin

Star Trails In Southern Skies Credit: Photograph by David MalinCopyright: Anglo-Australian Observatory

Equator

Axis of Rotation

Earth

Pole Star

Ecliptic Plane

23.5°

(Northward Journey of the Sun)

23 Dec

21 JUN

Uttaryan

DakshinayanSouthward journey of the Sun

Ecliptic

EquatorDaily Motion of the Sun

E

W

NS

21 JUN21 MAR,

23 SEP23 DEC

HORIZON

CELESTIAL EQUATOR

Annual and Daily Motion of the Sun

Moon’s Orbit

Sun

Earth

Earth Shadow

 

Total Lunar Eclipse

Schematic diagram of lunar eclipse. The sizes of the sun, moon and the earth and distances between them are not to scale. When moon passes through the shadow of the earth, it is eclipsed.

Schematic diagram of solar eclipse. The sizes of the sun, moon and the earth and distances between them are not to scale. The shadow of the moon falling on the earth causes the solar eclipse.

Sun

Earth

Moon

Total Eclipse

Partial Eclipse