Planets and Small Solar System Objects

From orbital movements to planetary positions, observational phenomena, moons and rings, including asteroids, cometary orbits and Pluto.

Let’s look at the Kepler experiment and orbital roots first; time and coordinates are also used in position and event calculations.

Let’s look at the phenomena in life first →

• When taking continuous photos of planets, why are they sometimes far apart and sometimes crowded together?

  Take a picture every time the same time passes, and the gaps between the pictures will tell you whether it is going fast or not.

• Knowing how flat an orbit is is not enough to tell us where a planet is?

  It's like placing a tilted ring: the shape, orientation and where the object goes are all explained.

• Why do we also need to write the year in the orbital parameters of the planet?

  Flip the year and see how the shape and orientation of the average orbit slowly changes.

• If you know which day a comet is closest to the sun, can you calculate where it is before and after?

  Let time pass through perihelion and observe the position, distance and speed in the elliptical orbit.

• If it only passes by the sun and does not circle back, how can the position be calculated?

  Instead of a "complete circle" cycle, use the closest distance and the time elapsed at that moment.

• The eccentricity is just a little more than 1, why can't everything be regarded as a parabola?

  Let the track go from slightly closed to slightly open, and compare the positions at the same time.

• How does a computer know where the planet is orbiting when one day changes on the calendar?

  Add up a series of small rhythmic changes to get the true calculated position at that moment.

• At this moment when you see the planet, is it still in the same position just now?

  It takes time for light to travel to the earth, and the telescope receives the news that started earlier.

• When do planets point in the same direction as the sun and when do they oppose the sun?

  Look at "conjunction, conflict, wide distance, and stay" separately, and then calculate the respective moments.

• The two planets "joined", did they collide in the sky?

  Seen from the Earth, two bright spots passing through the same direction line may still be separated up and down.

• Is the day when the earth is closest to the sun the hottest day?

  Perihelion and aphelion refer to distance extremes and cannot directly replace seasons or temperatures.

• The calendar says perihelion, is the lowest point of the distance curve really there?

  First use approximate dates to locate the same round of events, and then find the zero point of the derivative on the actual calculated distance curve.

• When the inclined orbit crosses the reference plane, why does it go "up" and "down" twice?

  The intersection point is through the reference plane, not through the earth.

• Does the same moon have the same address when viewed from the center of the earth and from where you are standing?

  When you reach out to look at a nearby object, changing the viewing position will change the direction; in astronomical calculations, you must also write down where to look from.

• Does Venus have to be brighter when its bright side is larger?

  How much light you see and how bright it looks are two different questions.

• Why aren’t planets always perfect circles in telescopes?

  The distance determines how big the disk is, and the oblateness and viewing angle determine how flat it is.

• Which side of Mars in the telescope is facing us today?

  First understand Mars' own north and south, longitude and light direction, and then understand the disk in the photo.

• There is only one Jupiter, so why are there two sets of rotation longitudes in the observation records?

  The equatorial cloud belts and high-latitude cloud belts do not rotate exactly the same and cannot be described by a "fixed surface" clock.

• Why do the four little dots next to Jupiter line up differently after a while?

  Enter the same time, first calculate the true position of the satellite, and then see where it falls next to the planet.

• Sometimes the rings of Saturn are wide and sometimes thin. Are they really getting thinner?

  At another viewing angle, the same flat circle changes from a wide ellipse to a thin line.

• Among those little dots next to Saturn, which one is Titan?

  First, calculate the positions of the eight satellites one by one according to Dourneau's theory, and then look at their arrangement next to Saturn.

• Knowing the orbit of a comet, how do you calculate where it will be on the star map tonight?

  Follow the orbit from perihelion time to the target date, and then change the observation starting point to the earth.

• Are two stones of the same brightness necessarily the same size?

  White stones are more reflective, and black stones may need to be larger to appear equally bright.

• Pluto is so far away, are we seeing its current position?

  First find its position around the sun, and then subtract the time it takes for the light to travel to the earth.