To enhance the ‘sun’ colours, create two layers with the blending mode set to Linear Dodge. Grab a large soft brush, and add dabs of colour behind the obelisk. Try using magenta on one layer and orange on another, but also feel free to experiment.
Next we’ll create the stars in the background. Open a new black document with the dimensions 1,000-x-1,000 pixels, at 300dpi, and add some noise (as in Step 08). Use a monochromatic Gaussian Blur set to about 10, adjust the levels (Cmd/Ctrl + L) and set the input values to 65; 1; 106. Delete large portions of the ‘Stars’ layer, then grab a soft Clone Stamp, setting the brush size to 250 pixels and the blending mode to Linear Dodge. Now have some fun creating a believable-looking star field.
Duplicate the star layer twice and add a Gaussian Blur of 30 points to the first layer, and one of 10 points to the second. Set the blending mode of both layers to Linear Dodge. Flatten the image, add some colour to it using Color Balance (Cmd/Ctrl + B). Experiment with different options, but make sure you have Preserve Luminosity ticked. Finally, make a Gradient Layer Mask beneath the stars. Copy it to the Obelisk piece behind the colour burst, stretch to fit then sharpen it (Filter > Sharpen > Sharpen).