Science

Neptune arrives today at the opposition: how to see the distant planet

The planet Neptune. (Image credit: Starry Night)

The outermost planet in the solar system, Neptune, is facing opposition today – this is how you can get a glimpse of the distant gas giant.

The planet Neptune reached opposition today (September 14) around 5 a.m. EDT (0900 GMT), when Earth passed directly between the Sun and Neptune, according to EarthSky.org. The opposition occurs when two astronomical objects, in this case, the sun and Neptune, are on opposite sides of the sky as seen from Earth. As a result of this cosmic alignment, Neptune will appear larger and brighter in the sky than at any other time of the year (although you will still need a pair of binoculars or a small telescope to see it).

During opposition, Neptune rises in the east as the sun sets in the west, offering sky watchers the best views after 9 p.m. local time. However, the planet will be visible and especially spectacular for most of the night tonight, in front of the constellation Aquarius, reaching its highest point in the night sky around midnight local time.

Related: Night Sky, September 2021 – What You Can See This Month [maps]

The planet Neptune reaches opposition at approximately 5 a.m. EDT (0900 GMT) on September 14, 2021, when Earth passes between the Sun and Neptune. (Image credit: Starry Night)

Yesterday (September 13), Neptune also passed perigee, or the closest point to Earth in its orbit, at a distance of 2.7 billion miles (4.3 billion kilometers), making it appear the brightest of all. year. The planet came closest to Earth about 20 hours before the opposition. However, as the eighth planet from the sun, Neptune’s great distance means that it is never visible to the naked eye, no matter how closely it orbits Earth.

“This world is five times fainter than the dimmest star that can be seen on a moonless night under a dark sky,” according to EarthSky.org. “You will need binoculars or a telescope for Neptune, as well as a detailed sky chart.”

To find Neptune, you can look to the left of the moon and look for the very nearby star Phi Aquarii, which is faint, but easily visible to the naked eye on a dark night, without moonlight. You can use this guide from The Old Farmer’s Almanac to determine when the moon rises and sets in your area, and plan when you may have the best chance of seeing the planet.

Since Neptune is so faint (even in opposition), we recommend using a good sky chart to help identify the distant planet and its neighboring landmarks in the constellation Aquarius. And while you may be able to get a glimpse of the planet with a good pair of binoculars, chances are you’ll have better luck with a 200-power telescope, according to EarthSky.org.

However, if the conditions for viewing the night sky are bad tonight, don’t worry! You will have more opportunities to observe Neptune among the stars of Aquarius throughout September.

Follow Samantha Mathewson @ Sam_Ashley13. Follow us on Twitter @Spacedotcom and on Facebook.

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