Mercury's distance from the Sun varies due to its highly elliptical orbit. On average, Mercury is about 36 million miles (58 million kilometers) away from the Sun, which is approximately 0.4 astronomical units (AU), where 1 AU is the average distance from the Earth to the Sun

. More specifically, Mercury's closest approach to the Sun (perihelion) is about 29 million miles (47 million kilometers), and its farthest distance (aphelion) is about 43 million miles (70 million kilometers)

. In summary:

• Average distance: ~36 million miles (58 million km)
• Closest distance (perihelion): ~29 million miles (47 million km)
• Farthest distance (aphelion): ~43 million miles (70 million km)

This elliptical orbit causes Mercury's distance from the Sun to fluctuate significantly as it completes an orbit every 88 Earth days