$\"\"$

\

The eccentricity of Halley $\"\"$ s elliptical orbit is $\"\"$ .

\

The length of the major axis is $\"\"$ .

\

$\"\"$ .

\

The polar equation of an ellipse with focus at the sun, semi major axis $\"\"$ , eccentricity $\"\"$ is $\"\"$ .

\

Substitute $\"\"$ and $\"\"$ .

\

$\"\"$

\

$\"\"$ .

\

The aphelion distance from a planet to the sun is $\"\"$ .

\

Substitute $\"\"$ and $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$ .

\

The maximum distance from the comet to the sun is $\"\"$ .

\

$\"\"$

\

The polar equation is $\"\"$ .

\

The maximum distance from the comet to the sun is $\"\"$ .