The tiyaarah and astrology is a form of shirk.

 The tiyaarah and astrology is a form of shirk.

Alhamdulillah, tiyaarah is a form of shirk.

As reported in hadith,

Abu Huraira reported Allah's Messenger (ﷺ) as saying:

There is no transitive disease, no Hammah, no star promising rain, no safar.

Sahih Muslim 2220.

It was narrated that Ibn 'Umar said:

The Messenger of Allah (ﷺ) said: 'There is no 'Adwa (contagion), no Tiyarah (evil omen) and no Hamah.' A Bedouinman stood up and said: 'O Messenger of Allah, what do you think about a camel that suffers from mange and then all other camels get mange?' He said: 'That is because of the Divine Decree. How else did the first one get mange?'" Note: The majority of scholars interpret this to mean that these things in and of themselves do not transmit or cause harm through supernatural or hidden means but that Allah is ultimately in control and any fearful superstition around these is false.

Sunan ibn Majah.

Vol. 1, Book 1, Hadith 86.

Tiyaarah is to make an evil omen saying something is he harmful.

For example seeing a leper and said,

Today is bad luck and this and this will happen today.

So a believer should not put his hope on something that it will harm him but should believe in Allah alone that nothing will happen to him save what Allah decreed.

Same as evil eye will never attack him unless Allah 's decree.

Allah says,

At-Taubah 9:51

قُل لَّن يُصِيبَنَآ إِلَّا مَا كَتَبَ ٱللَّهُ لَنَا هُوَ مَوْلَىٰنَاۚ وَعَلَى ٱللَّهِ فَلْيَتَوَكَّلِ ٱلْمُؤْمِنُونَ 

English - Sahih International

Say, "Never will we be struck except by what Allāh has decreed for us; He is our protector." And upon Allāh let the believers rely.