Story of Trishanku

Srimad Bhagavatam - Story of Trishanku 

Why did Satyavratha get the title ‘Trishanku’, and what were his wrongdoings? Why was Trishanku Swarga formed?

Satyavratha, son of Tribandhana is a descendent of Mandhata. He was not worthy of his name. He forcefully carried a just married brahmana girl. This act was strongly opposed by his parents.  

Satyavratha neither opposed his father nor apologized. Hence, left with no choice, his father cursed him to become a Chandala. Satyavratha wasn't angry with his father but had a grudge on Sage Vasishta. 

During that period, there was severe drought in the kingdom. Sage Viswamitra and his family were starving without food. Satyavratha, in chandala form, served food to Sage Viswamitra, though not according to the norms. Left with no choice, Sage Viswamitra accepted it. 

Satyavratha desired to end his life, but by the intervention of Vanadevatha (forest deity), he survived and waited to return to his kingdom. When his father passed away, Sage Vasishta called him to take over the kingdom as he was the only progeny.

Satyavratha had a desire to go to heaven in human form, which was instantly declined by Sage Vasishta. Sage Vasishta cursed Satyavratha for these 3 wrongdoings and named him Trishanku. 

Trishanku sought the help of Sage Viswamitra to gain access to heaven in human form.     

The Sage took pity and, using his yogic power, sent him to heaven. The devatas did not accept him as it was against the set rules. He was kicked back upside down. 

Sage Vishwamitra stopped Trishanku from falling back on the earth. He created a new heaven with all amenities exhausting his yogic powers. He expressed his inability to help him further.   

Sage Viswamitra had to restart penance to gain his position. 

Source: Bhagavatha Mahapurana