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In a few days we will be able to admire a rare and amazing astronomical phenomenon!

In a few days we will be able to admire a rare and amazing astronomical phenomenon!

The show coming soon will be the first in a very short series, just 5 PHEMU of Saturn's moons all year.
The show coming soon will be the first in a very short series, just 5 PHEMU of Saturn's moons all year.
Margarita Erio

Margarita Erio Italy meteorite 5 minutes

Everyone is ready, calendar in hand, to celebrate the next celestial event that promises to be a real spectacle. In fact, within a few days, We will witness the occultation of Tethys, one of Saturn's natural moons. It was discovered by Giovanni Domenico Cassini on March 21, 1684. But this occultation will be special Because it will happen on the level of another natural satellite of Saturn: Enceladus, It was discovered by William Herschel on August 28, 1789.

The phenomenon of mutual occultation between Saturn's moons will occur after that. This special and rare phenomenon is called PHEMU, which is derived from “reciprocal phenomena”.

PHEMUs, very cool rare phenomena

The PHEMUs themselves are shown By drops in satellite brightness, Sometimes they are so obvious that they can be observed simply with a telescope. It can be very useful for scientific research.

In fact, the chronology of these events allows astronomers to improve their knowledge of satellite orbits. Highlight potential disturbances.

So set your alarms because during the night from Sunday to next Monday, At 3:34 a.m. local time, Enceladus will eclipse Tethys. However, Tethys will not be completely obscured Because the latter has an apparent disk much larger than that of Enceladus.

Occultions can sometimes occur between satellites of the same planet, so it is a reciprocal phenomenon.
Occultions can sometimes occur between satellites of the same planet, so it is a reciprocal phenomenon.

The apparent disk does not correspond to the true diameter of a celestial body, but rather to what it appears to us observers. They exist at different distances between two celestial bodies, They may appear to be the same size when in reality they are completely different. As is the case with the sun and the moon, for example.

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In fact, the actual diameter of the two objects is also completely different, The average diameter of Tethys is 1,066 km and Enceladus is 498.8 km.

So we said that Tethys will not be completely obscured but ours will be Annular occultation.

It will not be easy at all to succeed in observing this scene, Because the size of the two satellites ranges between 10 and 11, So you need a good telescope to spot it, and during the occultation in the sky there will also be the Moon, a little further to the east. On Monday, our satellite will have just passed the full moon, which will occur on June 22. It will therefore remain largely sunlit, and thus particularly bright, to the point of complicating observing the occultation.

We will have four more opportunities to admire the mutual phenomenon

This won't be the only PHEMU of Saturn's moons this year, but it is the first, Four more mutual phenomena are expected to follow in the coming months.

PHEMU that will happen soon It will last 5.5 minutes at an altitude of approximately 30 degrees (28.185 degrees to be exact) Since Teti is brighter than Enceladus, Occultation will result in a decrease in volume of 0.206.

All that remains is to hope that weather conditions will not further hamper the observation of this rare spectacle. Indeed, in order for us to be able to observe these astronomical phenomena, You necessarily need clear, clear skies.

The ideal then is to stay away from urban areas So that light pollution does not disrupt the monitoring process Which, on this occasion, is already particularly complicated because Because the moon is in the waning gibbous phase.

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