Start representing the sun. Create firstly a round marking with
Elliptical Marquee Tool, pressing the shift button and paint it out with the
Gradient Tool, changing the gradient's type. Create after that a new layer again and represent on it an oval which must be painted too. Make many copies of the layer in case:
Layer – Duplicate Layer (ctrl+j). Use then the next option
Edit – Free Transform (ctrl+t) to place the rays around the sun.
Insert the flares, applying the same instruments.
Create a new layer again and group it out with the layer the sun is situated on:
Layer – Create Clipping Mask (ctrl+g). Create one more marking on the sun's surface and paint it out in white color. Change the layer's
Blending Mode on
Soft Light.
Combine all the layers composing the sun:
Layer – Merge Down (ctrl+e), and make a copy of the new layer (ctrj+j) and then make the lowest copy look totally white, using the next option:
Image – Channel Mixer:
Blur it out with
Filter – Blur – Gaussian Blur.
Then make two copies of the layer just to make the luminescence more intensive: