The smallest planet our solar system planets "Mercury" will be at Superior conjunction with the sun in the evening of Tuesday, May 21, 2019, at 4:00 Pm Doha local time. Qatar Calendar House (QCH) announced.

Superior conjunction of Mercury is a very important astronomical phenomenon, as it marks Mercury’s transition from the morning sky over the eastern horizon to the evening sky over the western horizon to appear after sunset. Astronomer expert at (QCH) Dr. Beshir Marzouk said.

During superior conjunction of Mercury, the center of three celestial objects (Sun, Earth, and Mercury) will be aligned on straight line, moreover Sun will be in between Mercury and Earth, and added Mercury will reach the farthest point from the Earth during Superior conjunction phenomenon; where it will be at 198 million Kilometers from Earth's center. 

Dr. Marzouk added, Mercury will pass very close to the Sun during superior conjunction, moreover it will pass behind the Sun as observing from Earth's surface, added it will be in opposite side of Earth, hence it totally unobservable for coming several weeks from all world hemisphere. 

Qatar and Arabic regions countries residents will be able to observe Mercury over western horizon during second week of June, 2019, approximately, where the duration between the time set of Mercury and sunset time will be increasing during coming few weeks, moreover, on Tuesday Mercury will be rise over Qatar sky (and all world counties sky) on the same time of sunrise time and both of Mercury and Sun will be set on western horizon on the same time approximately, so it will be impossible to observe Mercury on Tuesday. 

The superior conjunction of Mercury was occurred on Wednesday, January 30, 2019; while the next superior conjunction of Mercury will be occur on Wednesday, September 4, 2019.

For more information, there are two types of conjunction occurs for our solar system planets, Superior and Inferior conjunctions; where Superior conjunction occurs for all solar system planets, while Inferior conjunction occurs for two planets only (Mercury and Venus), because they orbits around the sun are inside Earth's orbit. 

Astronomer expert at Qatar Calendar House Dr. Beshir Marzouk