Question

Check out this sky-simulating website: www.stargazing.net/mas/planet4.htm This is an animated rectangular map of the Celestial Sphere, which will show us how things look from Earth’s Point of View (AS SEEN BY SOMEONE ON EARTH). Give the program your longitude and latitude. Our time zone offset is 8 hours West of Greenwich, which means that it is normally 8 hours earlier here than in Greenwich, England. The program will take Daylight Savings Time into account automatically if necessary.

a) What planets are favorably placed for viewing? Give your reasons. Be careful.

b) Now animate the display. A lot of things are happening quickly, so first just ignore everything but the Sun. Describe the path over the course of a year and explain what you are seeing.

c) Now try to ignore everything but the Sun and Mercury. Describe what you see over the course of at least one year and explain. You may have to play it a few times.

d) Now concentrate only on the planet Mars, watching it very closely for a few years to see the pattern. Is Mars moving retrograde today? If not, approximately when will it enter retrograde?

Answer 1

We need to understand few things first-

When Earth, the sun and the planet are all in a straight line.The planet is invisible to us because it is lost in the glare of the sun.

.The best time to see them is at ‘greatest elongation’, which is when they appear to be at their farthest from the sun as we see them.

a)Mars, Saturn, Jupitor, Pluto and Venus are favourly palced for viewing in August as they dont fall near on in line with the Sun at this time.

b) Sun is moving in a arc more precisely Ellipse.It is changing its elevation in the sky constantly and repeat this pattern each year.

c)Mercury is moving on close path with Sun(almost same path). Three times a year Mercury appears to turn around. After turning around, it appears to move back the way it came. This is called a retrograde orbit and is caused due to the difference in speeds at which the planets circle the Sun. At perihelion of its orbit it moves fastest while at aphelion slowest.

d)No, It is not moving retrogade today. It will enter retrogade after september 2020 as seen in animation.