Opposition is the best time to observe most planets and other celestial bodies in the solar system, as they appear at their largest and brightest in the night sky. This year, the most striking opposition event is Saturn’s opposition on September 8th. The planet will shine brightly throughout the night, visible to the naked eye.

To avoid missing any spectacular oppositions, you can observe this astronomical event using the Gskyer AZ70400 telescope.

• What Does Opposition Mean in Astronomy?

In astronomy, opposition means that a celestial body and the Sun are positioned 180 degrees apart as observed from Earth. So, when the Sun sets in the west, a planet appears in the east. Besides planets, comets, asteroids, and some other solar system objects can also reach opposition. An example of an opposition is a full moon. During this event, the Moon is opposite the Sun, and therefore, fully illuminated by sunlight.

• Planetary Opposition

Which Planets Can Be Seen During Opposition?

Opposition occurs only when Earth is positioned between the Sun and another planet, so only outer planets reach opposition. These planets include Mars, Jupiter, Saturn, Uranus, and Neptune.

Planetary oppositions occur approximately every year, with one exception: Mars. The "Red Planet" has an orbit and orbital speed similar to Earth's, so Earth "overtakes" Mars roughly once every 27 months. This is why Mars oppositions only occur every two to three years. Mercury and Venus orbit inside Earth's orbit, so they never reach opposition.

How to Find a Planet in Opposition?

To find a planet at opposition, look in the direction opposite the sunset. For several weeks around opposition, the planet will be in a favorable position for observation. So, check the weather forecast for your location, find a clear night near the time of opposition, and head outside to observe the planet in opposition.

• Why Is Planetary Opposition Interesting?

Opposition is the best time to observe a planet or other celestial bodies. During opposition, the object is fully illuminated by the Sun and shines brightly in the sky. Additionally, planetary opposition occurs when the planet is near its closest approach to Earth, which is when the planet appears largest in the sky. Mars experiences the most noticeable size change since it is the closest outer planet to Earth. Most importantly, opposition offers extended stargazing opportunities. A celestial body can be observed all night and is favorably positioned in the sky. Asteroids and other faint solar system objects are often discovered during their opposition, which is no coincidence.

• Upcoming Planetary Oppositions

September 8, 2024: Saturn's Solar Rush
On September 8, 2024, at 00:27 Los Angeles time (04:27 GMT), Saturn will reach its solar transit. The planet will shine with a brightness of 0.6 magnitude. To the naked eye, it will look like a yellowish dot; with binoculars, you may be able to see Saturn's oval shape. You will need at least a small telescope to see Saturn's rings. Look for the planet in the constellation Aquarius.

During the days surrounding the transit, observers may notice an unusual brightening of Saturn's rings, known as the “Seliger effect”. During the transit, the Sun shines directly on Saturn if viewed from Earth, so that the particles of Saturn and its rings are fully illuminated, casting no shadows. In addition, the sunlight interacts with the particles in the planet's rings and reflects them many times, making the rings appear brighter.

September 21, 2024: Neptune's Sunrise
Neptune will reach its solar transit on September 20, 2024 at 18:43 Los Angeles time (22:43 GMT). The planet will shine at magnitude 7.8 in the constellation Pisces. You can see Neptune immediately after sunset as it rises in the opposite direction to the Sun. It will reach its highest point in the sky around midnight and will be visible until dawn. However, even at its maximum brightness, Neptune is difficult to see without a telescope. Therefore, if you want to observe this distant planet, bring a telescope.

• Other upcoming planetary transits

Not only can planets reach their transits, but so can comets, asteroids and other solar system objects. Such events are more difficult to detect and are therefore more suitable for experienced astronomers. Solar transits are also the perfect time for “asteroid hunters”. If you want to discover a new asteroid, it's best to look in the direction opposite to the Sun, and you might get lucky!

Asteroid Sunrise

1. September 29, 2024: 20 Massalia (magnitude 9.2), Pisces.
2. October 7, 2024: 39 Laetitia (magnitude 9.1), Cetus.
3. November 13, 2024: Siren (11 Parthenope) (magnitude 9.8), Taurus.
4. December 13, 2024: Star of Justice (15 Eunomia) (magnitude 8.2), Sagittarius.

Dwarf Planet Punching the Sun

1. October 2, 2024: asteroid 120347 (Salacia) (magnitude 20.8), Pegasus.
2. October 17, 2024: Eris (136199 Eris) (magnitude 18.6), Cetus.
3. November 21, 2024: Sedna (90377 Sedna) (magnitude 20.7), Taurus.

• Frequently Asked Questions

Which planets are now at opposition to the Sun?
Saturn is the next planet in opposition to the Sun: it will reach opposition on September 8 at 00:27 GMT (04:27 GMT).

How often do planetary transits occur?
A planetary transit occurs when the Earth passes between the Sun and a planet. For most extraterrestrial planets, it happens every year. The only exception is Mars. Because the planet is so close to Earth and its orbit and orbital speed are similar to Earth's, our planet only passes between Mars and the Sun once every 27 months. So about once every two or three years, Mars makes a solar transit.

How long does the solar transit last?
The transit lasts for several weeks. You can observe the planet on any convenient date before or after the day of the transit. It will rise after sunset, reach its highest point at midnight, and set at dawn.

What is the opposition of an occultation in astronomy?
The opposition of a sunrise is a conjunction. During a planet's conjunction with the Sun, the planet is closest to the Sun in the sky. This is the most difficult period to observe a planet because the sun hinders observation. But there are other astronomical conjunctions that do not involve the Sun: for example, planetary conjunctions and lunar-planetary conjunctions. They are very interesting to observe!

• To summarize

Sunrise is the best time to observe the planets because they are largest and brightest at the time of the transit and are visible all night long. You don't even need to catch the exact moment of the transit to enjoy it. Use a Gskyer telescope to easily locate planets in the sky, choose a convenient time away from city lights, and observe the beauty of a planetary occultation!

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