updateSunTime (lat, lon) {
		const now = !this.date ? new Date() : this.date.toDate();
		const times = SunCalc.getTimes(now, lat, lon);
		this.sunrise = moment(times.sunrise);
		this.sunset = moment(times.sunset);
	}
Update the sunrise / sunset time depending on the location. This can be
used if your provider doesn't provide that data by itself. Then SunCalc
is used here to calculate them according to the location.
@param {number} lat latitude
@param {number} lon longitude