When the third trumpet sounds, a great star falls from heaven, flaming as a torch, and it fell upon the third part of the great rivers and the fountains of waters. And the name of the star is called Wormwood. The waters become bitter and many men die.

Bock (p.130-148) sees a connection with the bitterness that results when an I-development does not lead to solar qualities but falls back into a contracting and self-sufficient attitude.  Van Egmond (lecture 10 January 1995, p.17) relates the third trumpet to the air aspect and the astral soul. 

Schult (p.147) comments  more extensively on the third trumpet. The star Wormwood falls on earth in those waters that man uses to drink. John sees in the oceans a reflection of the distances of the etheric world, and in the rivers and water fountains on the main land symbols for the astral world and the astral body.

Wormwood, the plant Artemisia absinthium, used as medicine against amongst others intestinal worms, was seen in antiquity as a plant of the dead, because of its bitter taste. Till the Middle Ages  wormwood was planted on graves of the dead.

Wormwood is attributed to zodiac sign Scorpio, which is strongly related to the death. When the Sun runs through Scorpio, live in nature dies in the northern hemisphere. November is the month of Scorpio in which the Roman Catholic church celebrates the feast of the death, known as All Saints’ Day and All Souls’ Day.  Wormwood and all Saint John’s wort species affect the human digestion processes as the bitter substance influences the tempers. Wormwood or Artemisia absinthium, refers in its name to the Moon goddess Artemis, because the Moon is among the planets the summarizing center of the astral world. Scorpio governs in the human body sexuality and affects all astral passion that kills life.

In summary, the etheric is disappearing after the sounding of the second trumpet and the astral starts to dissolve when the third trumpet is blown.