… would you be concerned?
Well, it is true that, as I write, the Earth has been slowing down measurably. Although we have had the solstice on 21st June, the time of sunset (measured to the nearest minute) hereabouts will stay the same for several days to come.
Does that worry you?
Well, it shouldn’t as this is what happens around this time every year. The Earth goes round the Sun but its orbit is not a perfect circle. The orbit is an ellipse – in this instance a slightly stretched circle so that it has length and width not a simple diameter. This means that when the Earth is a little closer to the sun it moves a little bit faster because the pull of the Sun’s gravity is a bit stronger (this happens in January). Meanwhile at the other end of the year (now-ish) the earth is that little bit further away from the sun , the pull is a little bit less so the speed of the earth is a little bit slower.
This year aphelion (the place in the orbit when the Earth is furthest from the sun) will be on 6th July. After that it’s downhill all the way to December.
You can read a bit more on Wikipedia about the Earth’s orbit here.
Saint Mark Astronomy Group 