Neptune will reach opposition—when it appears on the opposite side of the sun in our sky—on September 26, 2026. Around that time, Neptune will be closest to Earth, brightest, and visible all night long. This will be the best time to observe Neptune in 2026.
Neptune at opposition in 2026
Moment of opposition: Neptune will reach opposition on September 26, 2026, at 00:00 UTC (8 p.m. EDT on September 25).
When to see: At opposition on September 26, 2026, Neptune will rise in the east at sunset and be visible all night. After opposition, Neptune will gradually disappear from the morning sky as it rises and sets about four minutes earlier each day.
Three months after opposition—by the end of December 2026—Neptune will be visible only in the evening sky, as it will set around midnight.
Six months after opposition—by the end of March 2027—Neptune will no longer be visible in the sky, as it will set around sunset. Neptune will reach solar conjunction on March 24, 2027.
How to identify: Around opposition on September 26, 2026, Neptune will be located about 10° west of Saturn. It can’t be seen with the naked eye, even at opposition, because it shines beyond the limit of naked-eye visibility. You will need a detailed finder chart, along with good binoculars or a telescope, to see it.
Constellation: Around opposition on September 26, 2026, Neptune will be located in the zodiac constellation Pisces, the Fish.
Closest approach of Neptune: Around opposition on September 26, 2026, Neptune will be closest to Earth, at a distance of about 28.88 AU (approximately 4.32 billion km).
Brightness: Around opposition on September 26, 2026, Neptune will be at its brightest in 2026, shining at magnitude +7.8.
Apparent size: Around opposition on September 26, 2026, Neptune will appear largest in 2026, measuring about 2.4″ across through a telescope.
What does “Neptune at opposition” mean?
Neptune reaches opposition when Earth passes between the sun and Neptune, the outermost planet in our solar system.
As the sun and Neptune lie on opposite sides of Earth during opposition, they appear on opposite sides of the sky, about 180° apart.
As a result, Neptune rises in the east when the sun sets in the west, reaches its highest point in the sky at midnight when the sun is below your feet, and sets in the west when the sun rises in the east.
How often does Neptune reach opposition?
Neptune takes about 165 Earth years to orbit the sun once. So when our Earth makes one full orbit around the sun, Neptune travels 1/165 of the way around the sun. So to create Neptune’s opposition, our Earth would have to travel an extra 1/165 of the way in its orbit, which takes about (1/165)*365 = 2 days to travel.
That’s why Neptune reaches opposition once every 1 year and 2 days, or 367 days.
Neptune’s opposition from 2026 to 2030
Here are the dates of Neptune’s opposition from 2026 to 2030:
| Date of opposition | Distance from Earth (AU) |
|---|---|
| September 26, 2026 | 28.88 |
| September 28, 2027 | 28.87 |
| September 30, 2028 | 28.86 |
| October 2, 2029 | 28.86 |
| October 5, 2030 | 28.85 |
Please bookmark Spaceandtelescope.com or follow us on Facebook and Twitter to get latest space news, upcoming skywatching events and astronomy-related content.
