juga sahasra jojana para bhānū /
līlyo tāhi madhura phala jānū //
~ Tulasīdāsa's Hanumān cālisā (caupāī 18)
This famous caupāī is often misinterpreted by many, where they take it as referring to an exact numerical distance b/w Sūrya & Pṛthvi. In actuality, this caupāī is not mentioning this info.
Firstly, juga is not used here in the sense of yuga, but in the sense of couple, pair or many. This 'yuga' (not time duration) is a synonym of yugma & yugala, as stated in Amarakośaḥ (2.5.38) -
yugmaṁ tu yugalaṁ yugaṁ
There's another term yuga which is a unit of time, and used for specific time durations. In śāstras, it's used to mean three specific durations - 5 yrs, Kṛta/Tretā/Dvāpara/Kali, and mahāyuga (caturyuga + sandhyāṁśas). For more info on the 5 yr duration, check this answer.
But as stated above, caupāī 18 (of Hanumān cālīsā) is not using the yuga that stands for time duration, but another yuga, whose meaning has been explained above through Amarakośa.
Secondly, sahasra doesn't necessarily mean 1000. Sahasra is used on several occassions in Veda too (for e.g. sahasrapāda, sahasrākṣa, etc.), but it's used in the sense of ananta, infinite or uncountable or just very big. There's a relevant śloka, which I quote below-
śatādhikāḥ samāḥ saṅkhyā geyāścānantya-vācikāḥ
[Words for] all numbers higher than hundred are also said to have the meaning 'uncountably many', in certain contexts.
Therefore, the meaning of juga sahasra jojana (in caupāī 18 of Hanumān cālīsā) is thousands and thousands of yojanas or many thousand yojanas or infinitely/uncountably many yojanas.
The distance from sun to earth, is mentioned in siddhāntic jyotiṣa śāstras, and easily calculable.
śaśirāśayaṣ ṭha cakraṃ te aṃśakalāyojanāni yavañaguṇāḥ /
prāṇenaiti kalāṁ bhaṁ khayugāṁśe grahajavo bhavāṁśe ’rkaḥ //
~ Āryabhaṭīya (1.6)
A circle multiplied by 12 is the moon’s signs. These multiplied by 30, 60, 10 are [respectively,] degrees, minutes, and yojanas. The earth moves one minute in one prāṇa. The circumference of the sky [in yojanas] divided by the rotations of a planet in a yuga is the [orbit of the] planet’s motion. The [orbit of the] sun is a sixtieth part of the circumference of the nakṣatra.
śaṣṭyā sūryābdānāṁ prapūrayanti grahā bhapariṇāham /
divyena nabhaḥparidhiṁ samaṁ bhramantas svakakṣyāsu //
~ Āryabhaṭīya (3.12)
By sixty solar years planets fulfill the circumference of the nakṣatra. Revolving equally in their own orbits, they [fulfill] the circumference of the sky by one divya [year].
The circumference of moon's orbit (Cm) is 12 X 30 X 60 X 10 = 216000 yojanas. The moon's sidereal rotations in a yuga (Rm) are 57753336 (as per Āryabhaṭīya 1.3-4). So, the moon travels Cm X Rm = 12474720576000 yojanas in a yuga consisting of 4320000 human yrs (called divya yr in Āryabhaṭīya 3.12). This is also the circumference of the sky (Ck) (nabhaṅparidhi) in yojanas. It's presupposed that all the grahas travel the same linear distance in a yuga. In other words, Cj X Rj = Ck is constant, for any j. In the case of the sun, whose rotations in a yuga (Rs) are 4320000 (as per Āryabhaṭīya 1.3-4), its circumference (Cs) is Ck / Rs = 2887666.8 yojanas. Therefore, the distance of the Sun from the earth is Cs / 2π ≈ 459585.37 yojanas (with Āryabhaṭa's value of π = 62832/20000 , as per Āryabhaṭīya 2.10).
In Goladīpikā, Parameśvara directly mentions above calculated distance b/w sun & earth -
The Sun is a fiery orb with a radius of 4410 yojanas. The radius of its orbit is equal to 459585 yojanas ~ Goladīpikā (2.48)