The effect of ‘ dark energy ’ ( i.e .
the \Lambda -term in Einstein equations ) is sought for at the interplanetary scales by comparing the rates of secular increase in the lunar orbit obtained by two different ways : ( 1 ) measured immediately by the laser ranging and ( 2 ) estimated independently from the deceleration of the Earth ’ s proper rotation .
The first quantity involves both the well-known effect of geophysical tides and the Kottler effect of \Lambda -term ( i.e .
a kind of the ‘ local ’ Hubble expansion ) , while the second quantity is associated only with the tidal influence .
The difference between them , 2.2 \pm 0.3 cm yr ^ { -1 } , can be attributed just to the local Hubble expansion with rate H _ { 0 } ^ { ( loc ) } = 56 { \pm } 8 km s ^ { -1 } Mpc ^ { -1 } .
Assuming that Hubble expansion is formed locally only by the uniformly distributed dark energy ( \Lambda -term ) , while globally also by a clumped substance ( for the most part , the cold dark matter ) , the total ( large-scale ) Hubble constant should be H _ { 0 } = 65 { \pm } 9 km s ^ { -1 } Mpc ^ { -1 } .
This is in reasonable agreement both with the commonly-accepted WMAP result , H _ { 0 } = 71 { \pm } 3.5 km s ^ { -1 } Mpc ^ { -1 } , and with the data on supernovae Ia distribution .
The above coincidence can serve as one more argument in favor of the dark energy .