Mercury, the innermost planet, will be at “superior conjunction” with the sun at 3.08am in Doha tomorrow, noted astronomer Dr Beshir Marzouk has said. The sun will be between Mercury and earth during this key astronomical phenomenon. Mercury is not visible while in conjunction with the sun but within the next week or so (around March 17) it will reappear on the eastern side of the sun and start becoming visible over the western horizon after sunset, he explained. People in Qatar can observe Mercury over the western horizon, during clear skies, 10 days after the superior conjunction occurs.