Valmiki says Rama was born on a Shukla Navami. Distance between Sun and Moon is > 96 deg. He also says Sun is exalted which is in Mesha Rashi( 0 to 30 deg). The he says Moon is in Punarvasu Nakshatra which ends at 93.20 deg from beginning of Aries. So Navami and Punarvasu cannot happen as per the method our Jyotish calculations are done today. Is Valmiki wrong or the way we do jyotish math wrong. I would kindly call upon the jyotish experts on this site to throw some light on this.
Added the exact shlokas from Bala Kaanda chapter 18 below with translation given at valmikiramayan.net
ततो यज्ञे समाप्ते तु ऋतूनां षट्समत्ययु:।
ततश्च द्वादशे मासे चैत्रे नावमिके तिथौ।।1.18.8।।
नक्षत्रेऽदितिदैवत्ये स्वोच्चसंस्थेषु पञ्चसु।
ग्रहेषु कर्कटे लग्ने वाक्पताविन्दुना सह।।1.18.9।।
प्रोद्यमाने जगन्नाथं सर्वलोकनमस्कृतम्।
विष्णोरर्धं महाभागं पुत्रमैक्ष्वाकुवर्धनम्।
तत: then, यज्ञे when sacrifice, समाप्ते was completed, ऋतूनाम् of seasons, षट् six, समत्ययु: were spent, तत: then, द्वादशे मासे in twelfth month, चैत्रे in Chaitra month, नावमिके तिथौ on the nineth day of the rising Moon, अदितिदैवत्ये presided by Aditi as devata, नक्षत्रे when the star (Punarvasu)was in ascendent, पञ्चसु ग्रहेषु and the five planets (Sun, Mars, Saturn, Jupiter and Venus), स्वोच्चसंस्थेषु in their own exalted houses, कर्कटे लग्ने in Karkata Lagna, वाक्पतौ when Brihaspati, इन्दुना सह along with Moon, प्रोद्यमाने was rising, कौसल्या Kausalya, जगन्नाथम् lord of the entire universe, सर्वलोकनमस्कृतम् bowed to by all the worlds, सर्वलक्षणसंयुतम् adorned with all the characteristics, विष्णो: Vishnu's, अर्धम् facet, महाभागम् highly fortunate, ऐक्ष्वाकुवर्धनम् perpetuating the Ikshvaku race, रामम् Rama, पुत्रम् as his son, अजनयत् gave birth .
Six seasons (one year) passed after the completion of the sacrifice. In the twelfth month of Chaitra on the ninth day (of the bright fortnight), with Aditi as presiding deity when the star Punarvasu was in the ascendent and the five planets Sun, Mars, Saturn, Jupiter and Venus, were exalted in their own house in karkata lagna, when Brihaspati was in conjunction with the Moon, Kausalya gave birth to a son: a facet of Visnu, Lord of the entire universe who received obeisance from all the worlds and was adorned with all auspicious signs, the venerable one to perpetuate the Ikshvaku race.