Vernal Equinox Day

Question

There is a custom お彼岸,ohigan,in Japan.

We go to お墓参り on 春分の日and秋分の日.

I wonderd why we go to grave on vernal equinox day.We go to grave several times in a year.お正月,I can understand because of new year greetings to ancestors,お盆 I can understand too because of ご先祖様の里帰り between 8/13-15,and 2 times お彼岸,I can't understand this.Why do we go to grave on equinox days?

Anybody in my family doesn't know the answer.But I found interesting things when I research how shoud I say 春分の日 in English.

Vernal Equinox Day

Equinox means 2つのものを均等に分けた、真ん中の分点.

So vernal equinox day is devide 昼が夜より長い日 and 夜が昼より長い日.

There is similar word"Equator".

Equator

赤道 in Japanese.It devides the earth to 北半球 and 南半球.

地球を均等に、2つに分けている.

And back to the first qestion,why we go to grave on equinox days.

彼岸と此岸

Something we can't see with our eyes divide this Shigan and that Higan.

Higan means あの世,and Shigan means この世,現世.

2つの世界が、見えない線によって分けられている,like Equator.

So maybe we go to grave to see ansestors on this equinox day since long long ago.

maybe(ㆁωㆁ*)

I found this invisible line,so interesting!

Sorry for katakoto English and Tokidoki Japanese.

I need more study and practice but I really enjoy talking various things with you.