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Solar, lunar, and planetary events to discover and to explore:
(read the applet details before)

You could answer most of the questions by naked eye observations, provided clear skies and spending some time...

Solutions and additional informations

Rare constellation of the bright planets Mar/Apr 2004

1. Watch the rare constellation of the bright planets Mar/Apr 2004

A rare planetary constellation will happen from the end of March until the beginning of April 2004: all of the bright planets Mercury, Venus, Mars, Jupiter, and Saturn will be visible at a glance. At what latitudes will the bright planets be visible ?

Hint: Use the different views (horizon, ecliptic, sky) for e.g. 2004 Mar 24.

2. Find the date and time of spring equinox for 2004.

Hint: Spring equinox occurs on March 19, 20 or 21 in the Northern Hemisphere. There are 12 hours of daylight, or, to get the precise time: the heliocentric longitude of the Earth must be 180°, and the geocentric longitude of the Earth 0° (or 360°). Choose the "Ecliptic " view to read the daylight hours and the longitudes.

3. How long is a Tropical Year ?

Hint: A Tropical Year is the interval between vernal (spring) equinoxes. Choose the "Ecliptic Zoom" view. Use the Julian Day (JD) to compute the interval.

4. Find the date and time of summer solstice 2004.

Hint: Summer solstice occurs on June 20 or 21 in the Northern Hemisphere. Sun reaches 90° in geocentric ecliptical longitude,and the declination of the Sun is at maximum. Choose the "Horizon" view, or the "Ecliptic" view.

5. How long are the seasons ?

Hint: Northern Hemisphere: Spring equinox: March 19, 20 or 21 Summer solstice: June 20 or 21 Autumnal equinox: September 22 or 23. Winter solstice: December 20, 21 or 22 Use the "Ecliptic Zoom" view, and the "Horizon" view. Use the Julian Day (JD) to compute the time intervalls.

6. Find the altitude of the noon Sun at summer solstice.

Hint: Summer solstice occurs on June 20 or 21 in the Northern Hemisphere. Choose the "Horizon" view. Click the Sun to read the altitude angle of the Sun at noon.

7. Determine the azimuth of the rising Sun at summer solstice.

Hint: Summer solstice occurs on June 20 or 21 in the Northern Hemisphere. Choose the "Horizon rect." view. Click the rising Sun to read the azimuth angle.

8. Find the date and time of perihelion 2004.

Hint: The perihelion is the Earth's annual closest approach to the Sun, occurs on Jan 2 to 5. Choose the "Ecliptic Zoom" view.

9. Find the date of Easter 2004.

1. Find the date of spring equinox. 2. Find the date of the next full moon. 3. Proceed to the next Sunday.

Hint: Choose the "Ecliptic Zoom" view, and find the date when the heliocentric longitude of the Earth is 180°

 

10. Explore the Transit of Venus on 2004, June 8.

1. Find the time of nearly equal geocentric longitudes of the Sun and Venus 2. Look at the heliocentric latitude of Venus (very close to is 0°) 3. Choose the "Horizon" view... 4. Will the transit be visible from your home location ? 5. Find the approximate duration of the transit.

Hint: Choose the "Ecliptic Zoom" view for 1. and 2.

11. Explore the visibility of the inner Planets (Mercury, Venus).

Mars and Venus

Hints: The geocentric longitude of the Sun must be 0° (360°), and the heliocentric longitude 180°. 1. Use the "Diagram" view, 2. Or select the "Ecliptic Zoom" view and find the dates of maximum elongation of the planet from the Sun, differentiate between morning and evening star. 3. Compare your results to the "Horizon" view.

12. Find the duration of the longest day and the shortest of 2004 for your location.

Hints: Select the "Horizon" view. Watch the daylight hours

13. Find the the day of earliest and latest sunrise 2004 for your location.

Hints: Select the "Horizon rect." view. Watch the small changes (decimal minutes)

14. Find the date and time of New Moon.

Hints: New moon is defined to occur at the moment of conjunction in ecliptic longitude with the Sun (the geocentric longitudes of the Sun and the Moon are equal). Select the "Ecliptic Zoom" view.

15. Check the duration of a Synodic month.

Hint: This is the period of time which elapses between the new moon and the next. Use the Julian Day (JD) to compute the intervalls. Select the "Ecliptic Zoom" view.

16. Determine the duration of a Draconitic month.

Hint: The interval of time between two successive transits of the Moon through its ascending node. Select the "Ecliptic Zoom" view. Use the Julian Day (JD) to compute the intervalls.

17. Determine the duration of an Anomalistic month.

Hint: The anomalistic month is the time between perigee passages. Use the Julian Day (JD) to compute the intervalls. Select the "Ecliptic Zoom" view.

18. Explore the Total Lunar Eclipse of 2004, Oct. 28.

Select the "Ecliptic Zoom" view.

Hints: 1. Find the time when the geocentric longitude of the Sun and the Moon differ by 180°. 2. Check the heliocentric latitude of the Moon close to 0° 3. Go to the "Horizon" view. Is the Moon above your local horizon ? 4. Find the region on Earth where the eclipse will be visible.

19. Watch the declination of the Moon and the azimuth at rise and set.

Hints: The azimut of the Moon at rise and set depends on the declination, which varies between +28.6° and -28.6° Select the "Horizon rect." view. Click the moon to read the azimuth angle.

Solutions

To be continued ...

© 2003-2007 J. Giesen