In Hindu's marriage function the married couples are needed to see the sky for seeing the Vashistar and Arundhati stars. Why do we need to see this and what is the impact on this one?
Arundhati and Vashishta are one of the greatest couples in Hindu texts. Arundhati is one of the pativratas. She is shown as a symbol of chastity and wifely devotion. She is unparalleled in service to husband. She is a lady who is worthy to be followed by other women.
Sage Agastya compares Sita with Sati Arundhati and says following to Rama,
But she this wife of yours is devoid of all those stigmas, an exemplary and an estimable lady, like Lady Arundhati. [Aranya Kanda Sarga 13 shloka 7]
In the Sundara Kanda of Ramayana, Sita Devi remembers some chaste ladies (pativratas) and couples who are revered as greatest. She also remembers Arundhati- Vashishta.
"Like the highly fortunate Sachi who waits upon Indra, like Arundhati on Vasishta, like Rohini on the Moon God, like Lopamudra on Agastya, like Sukanya on Chyavana, like Savitri on Satyavanta, like Srimati on Kapila, like Madayanti on Saudasa, like Kesini on Sagara, like Damayanti the daughter of Bhima, devoted to husband Nala, in the same way I am devoted to my husband Rama, the best in Ikshvaku dynasty." [Sundara Kanda sarga 24 shloka 10-12]
In marriage, a ritual of husband showing Arundhati nakshatra (Alcor) and star identified with Vashishta Maharshi (Mizar) in the constellation of Ursa Major to wife is performed. This is performed to message the newly married couple to live like Arundhati - Vashishta without any quarrels in their marital life. Husband shows the stars and advises wife to follow Sati Arundhati.