How to obtain coloured circles/spheres with and without a colour gradient in plots?

Hi to everyone, I need to insert colored circles and a sphere (only for the Sun) with and without color gradient in plots that represent the Sun and the Earth/Moon system, indicated as "Sun" and "Earth+Moon" in the following figures . The following ones are my current figures:

I want to replace the Sun and Earth+Moon(three objects that I simply plotted with a marker and its properties in matlab), with the following ones:

Can you help me to get the latter ones?

Answer 1

[Vishesh]

You can use the following MATLAB code for replacing the sun.

%position of sun
x=5;
y=5;


dark_yel=[255,143,0]/255;
yel=[255,242,0]/255;
length=100;
color_code=[linspace(dark_yel(1),yel(1),length)', linspace(dark_yel(2),yel(2),length)', linspace(dark_yel(3),yel(3),length)'];

msize=100;
for i=1:length
plot(x,y,'o','MarkerFaceColor',color_code(i,:),'MarkerSize',msize,'MarkerEdgeColor','none');
msize=msize-1;
hold on;
end
hold off;

For Earth and moon , you can use the following MATLAB code.

%position of moon and earth
x=1;
y=1;
plot(x,y,'O','MarkerFaceColor','#0000FF','MarkerSize',50);
hold on;
plot(x,y,'o','MarkerFaceColor','#808080','MarkerSize',20,'MarkerEdgeColor','none');

[Giuseppe]

Thank you very much @Vishesh! Can you also show how to plot the Sun as a 3-D sphere with the same colors gradient of 2-D case?

[Giuseppe]

@Vishesh can you show how to insert text (for instance, "Sun") and fix its position with respect to the size of the marker independently from units of plots?