Unity clock , sun rotation and day/night cycle

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class TimeController : MonoBehaviour {
    public bool isNight;
    public GameObject timeText;
    public GameObject Sun;
    private int heures;
    private int minutes;
    private float previousTime;
    private float myAngle;

    // Use this for initialization
    void Start () {
        heures = 8;
        minutes = 0;
        previousTime = Time.time;
    }

    // Update is called once per frame
    void Update () {

        //Ajout des minutes
        if(previousTime < Time.time - 1f)
        {
            minutes+=1;
            previousTime = Time.time;
            myAngle = 0.25f;
            Sun.transform.Rotate(myAngle, 0, 0); // Rotation de 0,25 degrés toutes les minutes in game
        }

        //Ajout des heures
        if(minutes >= 60)
        {
            heures++;
            minutes = 0;
        }

        //Fin d'une journnée
        if(heures >= 24)
        {
            heures = 0;
        }

        //Determination du jour et de la nuit
        if (heures >= 8 && heures<=21)
        {
            isNight = false;
        }
        else
        {
            isNight = true;
        }


        // Mise en forme du texte de l'horloge

        if (minutes < 10 && heures >=10)
        {
            timeText.GetComponent<UnityEngine.UI.Text>().text = heures + ":0" + minutes;
        }
        else if(heures < 10 && minutes >=10)
        {
            timeText.GetComponent<UnityEngine.UI.Text>().text = "0" + heures + ":" + minutes;
        }
        else if(minutes <10 && heures < 10)
        {
            timeText.GetComponent<UnityEngine.UI.Text>().text = "0" + heures + ":0" + minutes;
        }
        else if(heures >=10 && minutes >= 10)
        {
            timeText.GetComponent<UnityEngine.UI.Text>().text = heures + ":" + minutes;
        }
    }
}