Question

in hanuman chalisa tulishi das find out the distance of what

Answer 1

Tulsidas finds out the distance of Sun from earth.

जुग सहस्त्र जोजन पर भानु , 
लील्यो ताहि मधुर फल जानू||18||

In English -

Juga sahastra jojan par bhaanu |
Leelyo taahi madhur phal jaanu |

juga means the sum of Four Yugas (1 complete Mahayuga) with unit in divine years.
Satiyuga= 4800 divine years
Tretayuga=3600 divine years
Dwaparyuga=2400 divine years
Kaliyuga=1200 divine years

So 1 juga= 12000 years

Now next is sahastra (सहस्त्र) is common sanskrit word meaning "1000"
Next is jojan also know as Yojan that equals to 8 miles...!!

lets calculate distance of sun from earth

Juga X Sahastra X jojan (in miles) = 12000 X 1000 X 8 = 9,60,00,000 miles

Now 1 mile= 1.6km

So 9,60,00,000 miles= 9,60,00,000 X 1.6 km = 15,36,00,000km.
Today estimated distance by NASA is approximately 15,0000000 km which is close to above.

Answer 2

the distance of earth from sun